Tooth size and arch dimension in uncrowded versus crowded Class I malocclusions.

J Contemp Dent Pract. 2007;8(3):45-52

Authors: Poosti M, Jalali T

AIM: The purpose of this investigation was to examine the extent to which arch dimension or tooth size contributes to dental crowding. METHODS AND MATERIALS: Two groups of dental casts were selected. Each group consisted of 30 pairs of dental casts including equal male and female samples. The first group had Class I malocclusions without crowding or spacing. The second group exhibited Class I malocclusions with severe dental crowding (> a 5 mm space deficiency). The following parameters were measured and used to compare the two groups: individual and collective mesiodistal tooth diameters, dental arch length, as well as buccal and lingual dental arch widths in the canine and molar regions. To compare the two groups the Student's t-test with 95% confidence interval was used. RESULTS: Statistically significant differences in both tooth diameters and transverse arch dimensions were found between the two groups. The crowded group was found to have a significantly smaller maxillary arch width and larger tooth size when compared with the uncrowded group. CONCLUSION: The results of this study suggest under equal conditions (a Class I skeletal relationship) tooth size has a greater role in developing dental crowding.

PMID: 17351681 [PubMed - indexed for MEDLINE]

Anterior open bite treated with a palatal crib and high-pull chin cup therapy. A prospective randomized study.

Eur J Orthod. 2006 Dec;28(6):610-7

Authors: Torres F, Almeida RR, de Almeida MR, Almeida-Pedrin RR, Pedrin F, Henriques JF

The aim of this prospective randomized clinical study was to cephalometrically investigate the dentoalveolar and soft tissue changes produced by a removable appliance with a palatal crib associated with high-pull chin cup therapy in children with an Angle Class I anterior open bite (AOB) malocclusion. Thirty children (8 males and 22 females) with an initial mean age of 8.3 years and a mean AOB of 4.1 mm were treated with a removable appliance composed of a palatal crib associated with chin cup therapy for 12 months. A control group of 30 individuals (7 males and 23 females) closely matched for age, initial mean age 8.6 years, gender, and ethnicity with a mean AOB of 4.6 mm was followed without treatment. The measurements (means and standard deviations) were statistically analysed using a paired t-test. The results showed no significant differences in the level of molar eruption or in lower anterior face height, suggesting that the vertical control expected from the chin cup therapy did not occur. Dentoalveolar changes at the anterior region were evident, with statistically significant extrusion, retrusion, and lingual tipping of the maxillary and mandibular incisors (P < or = 0.05). However, these hard tissue changes did not imply soft tissue changes and the variables related to the soft profile were not statistically significantly different between the groups. The dentoalveolar changes at the anterior region of the dental arches were mainly responsible for closure of the AOB in patients treated in the mixed dentition.

PMID: 17101701 [PubMed - indexed for MEDLINE]

Evaluation of Swallowing Patterns of the Tongue Using Real-time B-mode Sonography.

J Contemp Dent Pract. 2006 Jul 1;7(3):67-74

Authors: Ardakani FE

The aim of the present study was to evaluate the swallowing patterns of the tongue using B-mode sonography. A total of 65 patients aged between eight and 35 years were enrolled in the study including 25 controls. The swallowing patterns of the 40 patients were divided into groups of ten normal, 12 inconsistent, and 18 abnormal. Eight patients with a swallowing abnormality had Angle Class I occlusions, two had Class II, and the remaining ten patients had Class III. The majority of abnormal or inconsistent swallowing patterns were found in cases of mandibular prognathism. Quantitative data was not analyzed in this study. The results of this study show that B-mode sonography, being a non-invasive procedure permitting direct visualization of the movements of the tongue in both coronal and sagittal planes, can be used with certainty for diagnosing swallowing abnormalities.

PMID: 16820809 [PubMed - indexed for MEDLINE]

A computerized photographic assessment of the relationship between skeletal discrepancy and mandibular outline asymmetry.

Eur J Orthod. 2006 Apr;28(2):97-102

Authors: Good S, Edler R, Wertheim D, Greenhill D

The aim of this study was to investigate the relationship between mandibular outline asymmetry and skeletal discrepancy in a sample of orthodontic patients (33 females, 33 males) aged from 8 to 19 years. Skeletal discrepancy was assessed in both the anteroposterior and vertical planes, using standard cephalometric analyses. All were photographed under standardized conditions and the photographs were then digitized for analysis using a computerized system to assess differences in four variables (area, perimeter, compactness and moment-ratio) between the right and left sides of the mandibular outline. The results showed good repeatability of the photographic, cephalometric and digitization methods. A statistically significant relationship was found between mandibular outline asymmetry and both anteroposterior and vertical skeletal discrepancy in this sample, when compared with patients with an average skeletal pattern. There appeared to be a statistically significant relationship between a reduced ANB angle (< 3 degrees) and mandibular outline asymmetry (P = 0.051), as well as between an increase in lower face height and mandibular asymmetry (P = 0.023).

PMID: 16431897 [PubMed - indexed for MEDLINE]

The treatment effects of Invisalign orthodontic aligners: a systematic review.

J Am Dent Assoc. 2005 Dec;136(12):1724-9

Authors: Lagrav&#xE8;re MO, Flores-Mir C

BACKGROUND: The authors conducted a systematic review of the literature to determine the treatment effects of the Invisalign orthodontic system (Align Technology), Santa Clara, Calif.). TYPES OF STUDIES REVIEWED: The authors reviewed clinical trials that assessed Invisalign's treatment effects in nongrowing patients. They did not consider trials involving surgical or other simultaneous fixed or removable orthodontic treatment interventions. RESULTS: The authors searched electronic databases (PubMed, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, Evidence Based Medicine Reviews, EMBASE Excerpta Medica, Thomsen's ISI Web of Science and LILACS) with the help of a senior health sciences librarian. They used "Invisalign" as the sole search term, and 22 documents appeared in the combined search. Thereafter, they used "clinical trials," "humans" and "Invisalign treatment effects" as abstract selection criteria. Only two published articles met these inclusion criteria, though after reading the actual articles, the authors determined that they did not adequately evaluate Invisalign treatment effects. Both articles identified methodological issues. CLINICAL IMPLICATIONS: The inadequately designed studies the authors found represented only a lower level of evidence (level II). Therefore, the authors found that no strong conclusions could be made regarding the treatment effects of Invisalign appliances. Future prospective randomized clinical trials are required to support, with sound scientific evidence, the claims about Invisalign's treatment effects. Clinicians will have to rely on their Invisalign clinical experience, the opinions of experts and the limited published evidence when using Invisalign appliances.

PMID: 16383056 [PubMed - indexed for MEDLINE]

Localized sequential use of resilient lining to generate orthodontic force in thermoformed active removable appliances.

J Orthod. 2005 Dec;32(4):235-40

Authors: Ng EW

A new modality of orthodontic treatment based on the thermoformed appliance was developed and trialled clinically. A light-cured resilient lining material commonly used for denture relining was placed locally and sequentially in thermoformed appliances to generate orthodontic forces. The new method appeared to be effective. All the presented cases showed substantial improvement in dental alignment. A number of orthodontic movements were demonstrated. Localized use of resilient lining in thermoformed orthodontic appliances appeared to be a promising alternative to other thermoformed active removable appliance (TARA) treatments. Further studies are required to optimize the procedures and explore its full potential.

PMID: 16333043 [PubMed - indexed for MEDLINE]

Masticatory performance in children and adolescents with Class I and II malocclusions.

Eur J Orthod. 2006 Apr;28(2):112-9

Authors: Toro A, Buschang PH, Throckmorton G, Rold&#xE1;n S

It is not fully understood whether masticatory performance is compromised in individuals with the more common forms of malocclusion (i.e. Class I and Class II). The aim of this prospective investigation was to establish the relationships between masticatory performance, malocclusion (type and severity), age, body size and gender, in children and adolescents. A total of 335 individuals were examined at the average ages of 6, 9, 12 and 15 years. Each subject's occlusal status was described by Angle classification and by the Peer Assessment Ratio (PAR) index. Masticatory performance was quantified by the median particle size (MPS) and the broadness of particle distribution using artificial food. Masticatory performance improved significantly with age. The 6-year-old children were less able to break down the food particles (MPS 4.20 mm2) than the 15 year olds (MPS 3.24 mm2). Analysis of covariance showed that age differences in performance are related to an increase in body size. There were statistically significant differences in masticatory performance between children with normal occlusion and those with a Class I malocclusion; no differences were found between normal occlusion and Class II malocclusion. Gender differences did not explain the variation in masticatory performance. It is concluded that occlusal indices are not reliable predictors of masticatory performance. Traditional descriptors of malocclusion type and severity apparently cannot explain most of the variation in masticatory performance in children and adolescents.

PMID: 16272209 [PubMed - indexed for MEDLINE]

Age-related changes in sagittal relationship between the maxilla and mandible.

Eur J Orthod. 2005 Dec;27(6):568-78

Authors: Lux CJ, Burden D, Conradt C, Komposch G

The aim of the study was to assess age-related changes in sagittal jaw relationship during pre-pubertal and pubertal development on the basis of angular [ANB, anteroposterior dysplasia indicator (APDI) and A-B plane angle] and linear (Wits, AF-BF, App-Bpp, and App-Pgpp) measurements. Lateral cephalograms of orthodontically untreated subjects were evaluated at 7, 9, 11, 13 and 15 years of age. Cephalometric standards and age-related changes were determined on the basis of Class I subjects with a good occlusion (n = 18, 10 males and 8 females). With respect to changes related to growth, the main findings were, in both genders, a statistically significant age-related decrease in ANB angle, App-Bpp and App-Pgpp, a significant increase in APDI, but no age-related change in Wits. A reduction of sagittal jaw distance during pre-pubertal and pubertal development was observed arising from a relative dominance of sagittal mandibular growth. For an evaluation of differences concerning jaw relationship in Class II subjects, a group with Class II division 1 malocclusions (n = 17) and a group with Class II division 2 malocclusions (n = 12 were compared with two control groups, i.e. the good occlusion group and a Class I group (n = 37). Conclusions about the sagittal discrepancy in Class II division 1 and Class II division 2 subjects depended on the geometric reference used in the various parameters, and further research is called for with respect to the diagnostic performance of the various measurements. Differences between Class II subjects and controls present at 15 years of age were already established at 7 years of age, but were less pronounced.

PMID: 16093257 [PubMed - indexed for MEDLINE]

Third molar angulation during and after treatment of adolescent orthodontic patients.

Eur J Orthod. 2005 Dec;27(6):590-6

Authors: Artun J, Thalib L, Little RM

The purpose of this study was to analyse the effect of premolar extraction therapy on third molar angulation during active treatment, and to test the significance of such changes on subsequent impaction of the third molars. Lateral cephalograms made before (T1) and after (T2) treatment and at long-term follow-up (T3) of 157 patients treated non-extraction (non-ex) or with extraction of four premolars (ex), all accurately diagnosed for impaction versus eruption of at least one third molar at T3, were evaluated. Linear regression models demonstrated that the maxillary third molars uprighted more from T1 to T2 (P < 0.05) and were less distally angulated at T2 (P < 0.01) in the ex than in the non-ex patients. No such differences were detected in the mandible (P > 0.05). The regression models also showed similar uprighting of the maxillary and mandibular third molars from T1 to T2 and similar angulation of the maxillary third molars at T2 in those patients with subsequent eruption and impaction (P > 0.05), but more mesially angulated mandibular third molars at T2 in the impaction patients (P < 0.01). Chi square testing demonstrated a higher frequency of distal tipping of the maxillary third molars from T1 to T2 in the impaction patients (P < 0.01), while mesial tipping from T1 to T2 of the mandibular third molars occurred with similar frequency in the two patient groups (P > 0.05). Chi square analysis also showed a higher frequency of greater than 30 degree distal angulation as well as an amount mesial angulation of the maxillary third molars at T2 (P < 0.01), and a higher frequency of greater than 40 degree mesial angulation of the mandibular third molars at T2 (P < 0.01) in patients with impaction than in those with eruption.

PMID: 16009666 [PubMed - indexed for MEDLINE]

A measuring system for facial aesthetics in Caucasian adolescents: reproducibility and validity.

Eur J Orthod. 2005 Dec;27(6):579-84

Authors: Kiekens RM, Maltha JC, van 't Hof MA, Kuijpers-Jagtman AM

A new measuring system to judge facial aesthetics in young Caucasians is presented. The system uses sets of three photographs (one frontal, one three-quarter smiling, and one lateral) as a stimulus. Scores are performed on a visual analogue scale (VAS) with separate sets of reference photographs for girls and boys. The choice of the reference photographs was based on a panel evaluation of facial aesthetics of 40 boys and 40 girls from the archive of the orthodontic department. Reproducibility of the new measuring system was tested on a series of photographic sets (one frontal, one three-quarter smiling, and one lateral view) of 64 patients, using a panel of 78 adult laymen and 89 professionals. The panel members assessed these sets of photographs on a VAS, in relation to the reference sets. The system was shown to be reproducible. Although the intra-observer reproducibility was low, the reliability coefficient was excellent (Cronbach's alpha > or = 0.98). Validity was tested by comparing the scores on the new scales with those of the three-quarter smiling photographic views on an earlier published scale. The correlation between the ratings on the new measuring system and the earlier published scale was 0.82 for laymen and 0.77 for professionals. The new system is simple and flexible in its use, and reproducible and valid for assessing facial aesthetics in young Caucasians. The system can be used in further investigations on the evaluation of facial aesthetics.

PMID: 16009665 [PubMed - indexed for MEDLINE]

[Non-extraction approach using RPE to correct Angle Class I malocclusion with moderate crowding: A cephalometric study]

Shanghai Kou Qiang Yi Xue. 2004 Dec;13(6):480-3

Authors: Gong FF, Lu J, Shen G

PURPOSE: To study cephalometric changes in Angle Class I malocclusion with moderate crowding treated orthodontically without extraction using rapid palatal expansion (RPE). METHODS: 9 patients with Angle Class I moderate crowding were orthodontically treated with a non-extraction approach using RPE and fixed edgewise appliances.The cephalometric analysis was performed at T1(pretreatment), T2(3 months after RPE) and T3(fixed retention period after active treatment). RESULTS: Lateronasal width, maxillary width, upper and lower first molar width significantly increased after rapid expansion (T1-T2) and after active treatment (T1-T3) with the significant difference in upper first molar width between T2 and T3. Total facial height, upper anterior facial height, the inclination of palatal plane and Y axis increased significantly (T1-T2, T1-T3). There were significant differences in the inclination of mandibular plane among T1, T2 and T3. CONCLUSION: Maxillary transverse width could increase using RPE. Rapid palatal expansion might not result in the anteroposterior changes.

PMID: 15619686 [PubMed - in process]

Clinical management in extraction cases using palatal implant for anchorage.

J Orthod. 2004 Dec;31(4):288-94

Authors: Giancotti A, Greco M, Mampieri G, Arcuri C

This case report presents a Class I extraction treatment in an adult patient with bimaxillary crowding using a palatal implant for anchorage control. The implant (pure titanium 6 mm SLA) is inserted in the middle of the palate, after a careful radiological assessment on a lateral cephalogram. At the end of the healing period (13 weeks), an anchorage device, such as a squared trans-palatal bar connecting the maxillary molars to the palatal implant, is projected and placed in order to obtain the posterior anchorage control. The orthodontic treatment was performed according to the bidimensional technique.

PMID: 15608343 [PubMed - indexed for MEDLINE]

Extraction of four first molars: a case for a general practitioner?

J Orthod. 2004 Jun;31(2):80-5

Authors: Seddon JL

It has been suggested that the extraction of four first molars 'doubles the treatment time and halves the prognosis' (Mills). It is also thought by some that these cases are unsuitable for treatment by General Dental Practitioners. The aim of this article is to illustrate that, with careful case selection, space analysis and good anchorage control, first molar extraction cases can be relatively straightforward

PMID: 15210922 [PubMed - indexed for MEDLINE]

[APDI and ODI estimated from substitute palate plane]

Shanghai Kou Qiang Yi Xue. 2004 Feb;13(1):13-6

Authors: Chen ZQ, Qian YF, Shen G, Wang GM

PURPOSE: The substitute palate plane was defined at the cephalometrics of noncleft patients. APDI and ODI were estimated from substitute PP. It is expected that the APDI and ODI estimated from PP (APDI',ODI')can be extended to the cleft patients to illustrate the anteroposterior and vertical relationship between maxilla and mandible. METHODS: The cephalometrics of 30 patients of C-I,C-II and C-III were traced and so were in 30 patients of normal overbite,deep overbite and open bite. The substitute palate plane(PP') was defined. The inclination of the PP to the FH, APDI and ODI, the inclination of the substitute PP to the FH,APDI' and ODI' were measured. The APDI and APDI' of C-I, C-II and C-III patients were compared,The ODI and ODI' of normal overbite, deep overbite and open bite patients were also compared by group t test. RESULTS: There was no significant difference between APDI and APDI' in C-I, C-II and C-III patients and also no significant difference between ODI and ODI' in normal overbite,deep overbite and open bite patients. It is showed the higher the ODI',the deeper the overbite. And the higher the APDI', the more mesial the molar relationship. CONCLUSIONS: The APDI and ODI estimated from substitute PP can be used as an important criterion to judge the vertical and anteroposterior development of the the maxilla, especially in palate clefts patients.

PMID: 15007472 [PubMed - indexed for MEDLINE]

Unilateral Angle II in functional lateralities.

Eur J Orthod. 2004 Feb;26(1):93-8

Authors: Heikkinen T, Poikela T, Gr&#xF6;n M, Alvesalo L

The aim of this study was to explore unilateral Angle II-type malocclusion prevalences in functionally true right-sided (TRS) and non-right-sided (NRS) children having one or more left-sided functions (eye, hand, foot). A half cusp sagittal relationship of the upper and lower M1 and Dm2 was determined on dental casts of 1423 young American black and white children in a cross-sectional sample with the mean age of 8.5 years (range 6-12 years). Hand, foot and eye preferences were recorded at the age of 4 years during the Collaborative Perinatal Study. The prevalences of symmetric bilateral Angle I and II and asymmetric unilateral Angle II right and Angle II left cases were compared between TRS and NRS children using Chi-square analysis. In general, unilateral Angle II right occurred in 9 per cent of the population and Angle II left in 6.5 per cent. In moderate non-right sideness (two-thirds of left dominant functions), these proportions were 17 and 3 per cent, respectively, and in true right sidedness 8 and 6 per cent, respectively. TRS subjects were more symmetric (bilateral Angle I or II in 85 per cent of cases) than NRS children (80 per cent), and the differences were statistically significant (P < 0.02). These results highlight the anatomical relationships of structures supporting the occlusion and the symmetry/asymmetry of the neurocranium, cranial base, masticatory apparatus, and probably also the sidedness and the growth-stimulating effect of lateralized jaw function. Based on the results and considering earlier observations on brain asymmetry in functional lateralities, it can be hypothesized that a normal symmetric sagittal occlusal relationship is based on unilateral sagittal compensatory growth to maintain optimal bite, challenging early preventive orthodontic treatment in suspect unilateral Angle II cases.

PMID: 14994888 [PubMed - indexed for MEDLINE]

An investigation of cervicovertebral morphology in different sagittal skeletal growth patterns.

Eur J Orthod. 2004 Feb;26(1):43-9

Authors: Baydaş B, Yavuz I, Durna N, Ceylan I

The purpose of the present study was to examine and compare cervicovertebral morphology in subjects with different sagittal skeletal patterns. The material comprised lateral head films of 90 untreated subjects, 45 girls and 45 boys, aged 13-15 years. The radiographs were obtained in the natural head position using a fluid level method. The subjects were divided into three groups according to ANB angle: ANB angle between 1 and 5 degrees (skeletal Class I), larger than 5 degrees (skeletal Class II), and smaller than 1 degree (skeletal Class III). Each ANB group consisted of 30 subjects, 15 girls and 15 boys. Twenty-nine linear and four area measurements were used to assess cervicovertebral morphology. Differences between the ANB groups and between genders were assessed by means of analysis of variance and the least significant difference test. In addition, cephalometric measurements for all subjects were subjected to discriminant analysis. The results of the analysis of variance showed that there were statistically significant differences in the measurements of the lumen length of C1, inferior depths of C2 and C4, anterior intervertebral spaces of C2 and C3, posterior intervertebral space of C3, and anterior and posterior body heights of C4 among the ANB groups. The total length of C1, inferior depths of C2-C5, anterior intervertebral spaces of C2-C4, posterior intervertebral space of C2, anterior body heights of C4 and C5, and posterior body heights of C3-C5 demonstrated significant gender differences. The results of the discriminant analysis indicated that 54.4 per cent of the original grouped cases were correctly classified in the total sample. The final discriminant model was able to classify correctly 20 of the 30 Class I subjects (66.7 per cent), 17 of the 30 Class II subjects (56.7 per cent), and 12 of the 30 Class III subjects (40.0 per cent).

PMID: 14994881 [PubMed - indexed for MEDLINE]

Maxillary retention: is longer better?

Eur J Orthod. 2003 Feb;25(1):65-9

Authors: Destang DL, Kerr WJ

Two different maxillary retention regimes were compared to ascertain if differences in posttreatment relapse existed. The patient pool was derived from subjects being treated at two orthodontic departments in the west of Scotland. Group 1 (20 patients) followed a 6 month regime using removable upper Hawley retainers for a period of 3 months full time and 3 months nights only. Group 2 (18 patients) followed a 1 year regime of 6 months full time and 6 months nights only. The results revealed that maxillary incisor alignment, as determined by Little's irregularity index, had relapsed by an average of 50 per cent of the end of retention value 3 months out of retention in Group 1 but only 23 per cent in Group 2. Although the actual mean values for relapse were 0.77 and 0.23 mm, respectively, seven subjects in Group 1 showed relapse of more than 3 mm as compared with only one in Group 2. This suggests that retaining a case for 1 year rather than 6 months is clinically beneficial.

PMID: 12608725 [PubMed - indexed for MEDLINE]

Cleft type and Angle's classification of malocclusion in Korean cleft patients.

Eur J Orthod. 2002 Dec;24(6):647-53

Authors: Baek SH, Moon HS, Yang WS

This study was performed to investigate the contributing factors, such as cleft type, side of cleft, patient's age, and gender, associated with Angle's classification of malocclusion in Korean cleft patients. The records of 250 cleft patients (175 males, 75 females) who attended the Department of Orthodontics, Seoul National University Dental Hospital between 1988 and 1999 were examined. The percentages of subjects with cleft lip (CL), cleft lip and alveolus (CLA), cleft palate (CP), and cleft lip and palate (CLP) were 7.6, 19.2, 9.6, and 63.6, respectively. The overall distributions of unilateral and bilateral clefts were 76 and 24 per cent, respectively. The overall percentages of Class I, II, and III malocclusions were 18.5, 8.8, and 72.7. The frequency of Class III malocclusions was most prevalent in all age groups. Bivariate analysis showed that whilst gender was not significant, the type of cleft significantly influenced the development of a Class III malocclusion (P < 0.01). Using logistic regression analysis, subjects in the CP (P < 0.05) and CLP groups (P < 0.01) were 3.9 and 5.5 times more likely to have a Class III malocclusion than those in the CL group. There was, however, no statistical difference in the prevalence of a Class III malocclusion between the CL and the CLA groups (P > 0.05). When the degree of cleft involvement in the palate increased, so did the predominance of a Class III malocclusion.

PMID: 12512782 [PubMed - indexed for MEDLINE]

The extraction of permanent second molars and its effect on the dentofacial complex of patients treated with the Tip-Edge appliance.

Eur J Orthod. 2002 Oct;24(5):501-18

Authors: Greatrex PA, Sampson WJ, Richards LC, Twelftree CC

The aim of this investigation was to assess the dentofacial changes in a group of patients consecutively treated with Tip-Edge appliances and the extraction of four permanent second molars by one specialist orthodontic practitioner. Before and after treatment lateral cephalograms and study cast measurements of 45 individuals, 26 females (mean age 13.8 years) and 19 males (mean age 13.9 years), were collated and statistically analysed. Cephalometric variables that exhibited, before treatment, significant sex differences, included SNA, SNB (both smaller in males, P < 0.05) and U1-NA degrees (P < 0.05), nasolabial angle (P < 0.05), and upper lip length P < 0.01 (all larger in males). After treatment, sex differences were demonstrated for SNA (smaller in males, P < 0.05), mandibular length (P < 0.01), upper face height (P < 0.05), lower face height (P < 0.01), anterior face height (P < 0.001), posterior face height (P < 0.01), nasolabial angle (P < 0.05), and upper lip length and thickness (P < 0.001; all larger in males). For the cast analysis, before treatment differences indicated larger values for males than females for lower arch inter-canine, premolar, and molar widths, arch depth (all P < 0.05), tooth size, and arch length (P < 0.01). Similar findings were noted in the upper arch except for inter-canine and premolar arch width. Despite most arch variables displaying sex differences, no gender effect was found for irregularity or crowding parameters. The same variables exhibited significant sex differences and changes after treatment (except tooth size, lower arch depth, and upper arch inter-canine width). Overall, the pattern of correction exhibited by the subjects included dental, skeletal, and soft tissue changes. Males tended to have greater mean increases in mandibular skeletal and soft tissue variables compared with females. Both males and females had increases in most dental arch variables measured from the study casts. Both sexes demonstrated a small uprighting, but statistically non-significant distalizing of the buccal segments. The lower incisors in the sagittal plane revealed a mean tendency to remain in their pre-treatment positions, with some individual variation. Overall, the treatment results were considered favourable, but case selection appeared to bias towards Angle Class I skeletal patterns of average to slightly reduced facial height, overbite and overjet < or = 4 mm, lip competence, no incisor protrusion, and moderate tooth size to arch length discrepancy (3-3.5 mm lower arch, 1 mm upper arch). Further evaluation of third molar eruption responses may provide insight into appropriate timing of second molar extractions.

PMID: 12407946 [PubMed - indexed for MEDLINE]

Properties of the ANB angle and the Wits appraisal in the skeletal estimation of Angle's Class III patients.

Eur J Orthod. 2002 Oct;24(5):477-83

Authors: Iwasaki H, Ishikawa H, Chowdhury L, Nakamura S, Iida J

The aims of the present study were: (1) to investigate the statistical differences in jaw relationship assessments with the ANB angle and the Wits appraisal in Angle Class III children, and (2) to suggest guidelines for the use of these two parameters in this group of children. Seventy-five Angle Class I children with anterior crowding (male, 37; female, 38) and 96 Angle Class III children with anterior crossbite (male, 38; female, 58) were examined. All had undergone treatment that started at 8 or 9 years of age. Pre-treatment lateral cephalograms were used cross-sectionally for the analysis. The mean age was 8 years 7 months +/- 9 months in the Class I subjects, and 9 years 0 month +/- 7 months in the Class III subjects. To compare the assessments using ANB angle and the Wits appraisal in the Angle's Class III subjects, nine measured values from each individual subject were converted into Z scores in relation to the means and standard deviations of the two parameters in the Angle Class I subjects. The jaw discrepancy is assessed more severely using the ANB angle than by the Wits appraisal in these Angle Class III subjects. The paired t-test showed that the Z score of the ANB angle was significantly smaller than that of the Wits appraisal (P < 0.001). In Angle Class III subjects with a counter-clockwise mandibular rotation and a flattened occlusal plane, the ANB angle is a more critical cephalometric parameter than the Wits appraisal.

PMID: 12407943 [PubMed - indexed for MEDLINE]

The B.S.S.O. M.Orth. Prize of the Royal College of Surgeons of England 1998.

J Orthod. 2000 Dec;27(4):287-94

Authors: Patel S

PMID: 11099565 [PubMed - indexed for MEDLINE]

The retraction of upper incisors with the PG retraction system.

Eur J Orthod. 2000 Feb;22(1):33-41

Authors: Din&#xE7;er M, Gülşen A, Türk T

The aim of this study was to evaluate the effect on the dentoalveolar structures of the application of PG springs for retraction of upper incisors and to compare the outcome with the effect of a closed coil spring retraction system. Thirty-six subjects with Angle Class I or Class II malocclusions were selected for the study. Each subject had the two upper first premolars extracted and presented a symmetrical extraction space of at least 3 mm distal to the lateral incisors after canine retraction. The subjects were divided into two groups, the PG group with 17 subjects and the coil group with 19 patients. One group had the incisors retracted by PG universal retraction springs, whereas in the other a closed coil spring system was used. The average chronological ages were 18 years 4 months for the PG group, and 18 years 7 months for the coil group. In both groups the springs were activated to produce an initial force of 150 g per side. To examine the type of movement of the anterior and posterior teeth, and the time and rate of space closure, 20 parameters were measured and evaluated statistically with Wilcoxon and Mann-Whitney U-tests. In both groups the incisor retraction was accompanied by mesial movement of the buccal segments. Distal movement of the root apex of the incisors was observed in both groups, although more pronounced in the PG group (P < 0.01). A significant incisor intrusion resulting in a decrease in overbite was found in the PG group, whereas the deep bite increased significantly in the coil spring group. The PG spring produced a three-dimensional control in the movement of the upper incisors, so that application of additional intrusive mechanics after completion of the incisor retraction became unnecessary.

PMID: 10721243 [PubMed - indexed for MEDLINE]

Evaluation of apical root resorption following extraction therapy in subjects with Class I and Class II malocclusions.

Eur J Orthod. 1999 Oct;21(5):491-6

Authors: Taner T, Ci&#x11F;er S, Sençift Y

The purpose of this study was to determine the amount of root resorption during orthodontic treatment, and to examine the relationship between tooth movement and apical root resorption. Twenty-seven Class I and 27 Class II patients treated with edgewise mechanics following first premolar extractions were selected. The following measurements were made on the pre- and post-treatment cephalograms: upper central incisor to palatal plane distance, the inclination of upper central incisor to the FH and AP planes, the perpendicular distances from the incisor tip to the AP and PTV planes, and incisor apex to PTV. The amount of apical root resorption of the maxillary central incisors was determined for each patient by subtracting the post-treatment tooth length from the pre-treatment tooth length measured directly on cephalograms. Intra-group differences were evaluated by the Student's t-test and inter-group differences by the Mann-Whitney U-test. For correlations the Pearson correlation coefficient was used. The results show that there was a mean of approximately 1 mm (P < 0.01) of apical root shortening in Class I patients, but in Class II division I subjects the mean root resorption was more than 2 mm (P < 0.001). The inter-group differences were statistically significant. No significant correlations were found between the amount of apical root resorption and tooth inclination, or the duration of active treatment.

PMID: 10565089 [PubMed - indexed for MEDLINE]

Craniofacial morphology in 6-year-old Icelandic children.

Eur J Orthod. 1999 Jun;21(3):283-90

Authors: Johannsdottir B, Thordarson A, Magnusson TE

The purpose of the study was to describe the craniofacial characteristics of 6-year-old Icelandic children, make a normative standard for children with an Angle Class I molar relationship, and compare them to those with an Angle Class II molar relationship. The material consisted of the radiographs of 363 children, 184 (50.7 per cent) boys and 179 (49.3 per cent) girls with a mean age of 6 years 7 months (range: 5 years 7 months-7 years 8 months). Twenty-two reference points were digitized and processed by standard methods with the Dentofacial Planner computer software program. The 33 variables calculated included both angular and linear. Two sample t-tests were used to study the differences between different groups. Only minimal differences could be noted between sexes in sagittal and vertical angular measurements. Linear measurements, on the other hand, were usually larger for the boys. When compared with Norwegian material of the same age group, similar trends were observed between sexes in both studies, but the Icelandic children showed slightly more mandibular prognathism and a lower mandibular plane angle. When compared with children with an Angle Class I molar relationship, children with an Angle Class II molar relationship did not have a different maxillary prognathism nor a different mandibular length. Cranial base dimensions were all significantly greater and the cranial base flexure was also significantly more obtuse in the distal group.

PMID: 10407537 [PubMed - indexed for MEDLINE]

An appraisal of the Peer Assessment Rating (PAR) Index and a suggested new weighting system.

Eur J Orthod. 1999 Apr;21(2):181-92

Authors: Hamdan AM, Rock WP

The PAR Index was developed to measure treatment outcome in orthodontics. Validity was improved by weighting the scores of some components to reflect their relative importance. However, the index still has limitations, principally due to the high weight assigned to overjet. Difficulties also arise from the application of one weighting system to all malocclusions, since occlusal features vary in importance in different classes of malocclusion. The present study examined PAR Index validity using orthodontic consultant assessments as the 'Gold standard' and clinical ranking of occlusal features and statistical modelling to derive a new weighting system, separate for each malocclusion class. Discriminant and regression analyses were used to derive new criteria for measuring treatment outcome. As a result a new and more sensitive method of assessment is suggested which utilizes a combination of point and percentage reductions in PAR scores. This was found to have better correlations with the 'Gold standard' than the PAR nomogram.

PMID: 10327742 [PubMed - indexed for MEDLINE]

Mandibular shape and skeletal divergency.

Eur J Orthod. 1999 Apr;21(2):145-53

Authors: Ferrario VF, Sforza C, De Franco DJ

Pre-treatment lateral cephalograms of 41 skeletal Class I girls aged 11 to 15 were divided according to MP-SN angle: lower than 28 degrees (hypodivergent, 10 girls), between 31 and 34 degrees (normodivergent, 18 girls), or larger than 37 degrees (hyperdivergent, 13 girls). The mandibular outlines were traced and digitized, and differences in shape were quantified using the elliptic Fourier series. Size differences were measured from the areas enclosed by the mandibular outlines. Shape differences were assessed by calculating a morphological distance (MD) between the size-independent mean mathematical reconstructions of the mandibular outlines of the three divergency classes. Mandibular shape was different in the three classes: large variations were found in hyperdivergent girls versus normodivergent girls (MD = 4.61), while smaller differences were observed in hypodivergent girls (MD versus normodivergent 2.91). Mean size-independent mandibular shapes were superimposed on an axis passing through the centres of gravity of the condyle and of the chin. Normodivergent and hyperdivergent mandibles differed mostly at gonion, the coronoid process, sigmoid notch, alveolar process, posterior border of the ramus, and along the mandibular plane. A significant size effect was also found, with smaller mandibles in the hyperdivergent girls.

PMID: 10327738 [PubMed - indexed for MEDLINE]

The Denture Frame Analysis: an additional diagnostic tool.

Eur J Orthod. 1998 Oct;20(5):579-87

Authors: Celar AG, Freudenthaler JW, Celar RM, Jonke E, Schneider B

The purpose of this study was to evaluate the Denture Frame Analysis. This adjunctive cephalometric analysis of the lateral headfilm was introduced in Japan, but no data exist for the Caucasian population at present. One-hundred-and-six Caucasians were randomly selected and assigned to one of four groups, according to their malocclusion: Angle Classes I, II, and III, and anterior open bite. Statistical testing showed significant differences among the four groups for most of the measurements investigated. The Denture Frame Analysis distinguished the different types of malocclusion, and evaluated skeletal and dental relationships. The occlusal plane aids in the determination of the objectives and limits of orthodontic therapy.

PMID: 9825560 [PubMed - indexed for MEDLINE]

Effect of growth and development on cephalometric shapes in orthodontic patients: a Fourier analysis.

Eur J Orthod. 1997 Dec;19(6):669-80

Authors: Ferrario VF, Sforza C, Poggio CE, Colombo A, Cova M

The age- and gender-related shape variations of the craniofacial skeleton in skeletal Class I children were quantified using a Fourier analysis on the pre-treatment lateral head films of 122 orthodontic patients (age range 7-15 years), who were subdivided into six groups for sex and age (2-year intervals). Seven landmarks representative of the maxillo-mandibular sagittal and vertical relationship were identified and digitized. The contiguous landmarks were connected by segments, the form was normalized with respect to its orientation and size, and a Fourier analysis of the contour was performed. Mean values of the cosine and sine coefficients of the first six harmonics in the sex and age classes were computed. The size-standardized outlines of the oldest boys were narrower and longer than the outlines of the youngest boys (differences at gonion, menton, sella and nasion). Shape differences between mean plots in girls were negligible. In the youngest patients, girls had a larger size-independent shape in the mandibular region; their shape was narrower (anterior-posterior direction) and longer (vertical direction) than male shape. In the oldest patients, boys had a larger size-independent shape at gonion, and a narrower shape at articulare and pogonion than girls. Size increased from the youngest to the oldest boys; size differences were not conspicuous in girls. Within an age class, male size was always larger than female. Fourier analysis allowed a global evaluation of the cephalometric forms, with separate quantifications of the age- and gender-related differences in size and shape.

PMID: 9458600 [PubMed - indexed for MEDLINE]

Localisation of deformations of the midfacial complex in subjects with class III malocclusions employing thin-plate spline analysis.

J Anat. 1997 Nov;191 ( Pt 4):595-602

Authors: Singh GD, McNamara JA, Lozanoff S

This study determines deformations of the midface that contribute to a class III appearance, employing thinplate spline analysis. A total of 135 lateral cephalographs of prepubertal children of European-American descent with either class III malocclusions or a class I molar occlusion were compared. The cephalographs were traced and checked, and 7 homologous landmarks of the midface were identified and digitised. The data sets were scaled to an equivalent size and subjected to Procrustes analysis. These statistical tests indicated significant differences (P < 0.05) between the averaged class I and class III morphologies. Thinplate spline analysis indicated that both affine and nonaffine transformations contribute towards the total spline for the averaged midfacial configuration. For nonaffine transformations, partial warp 3 had the highest magnitude, indicating the large scale deformations of the midfacial configuration. These deformations affected the palatal landmarks, and were associated with compression of the midfacial complex in the anteroposterior plane predominantly. Partial warp 4 produced some vertical compression of the posterior aspect of the midfacial complex whereas partial warps 1 and 2 indicated localised shape changes of the maxillary alveolus region. large spatial-scale deformations therefore affect the midfacial complex in an anteroposterior axis, in combination with vertical compression and localised distortions. These deformations may represent a developmental diminution of the palatal complex anteroposteriorly that, allied with vertical shortening of midfacial height posteriorly, results in class III malocclusions with a retrusive midfacial profile.

PMID: 9449078 [PubMed - indexed for MEDLINE]

Occlusal traits in a group of school children in an isolated society in Jerusalem.

Br J Orthod. 1997 Aug;24(3):229-35

Authors: Ben-Bassat Y, Harari D, Brin I

The prevalence of occlusal features in 939 children, aged 6-13 years, belonging to an ultra-orthodox community of Jewish Ashkenazi descent living in Jerusalem was studied clinically. Sexual dimorphism was found for overjet, overbite, and habit practising. About one-quarter of the sample exhibited some degree of occlusal mutilation due to caries, thus creating a 'caries-affected' subgroup, the rest forming the 'caries-free' subgroup. In the latter set, normocclusion was scarce (7.4 per cent), Class I being the most frequent malocclusion (49.1 per cent). Caries had a significant effect on the symmetry of bilateral occlusal relationships, lower dental midline deviation, and on crowding/spacing conditions in the mixed dentition stage (except for the maxilla in late mixed dentition). The low prevalence of normocclusion can be attributed to genetic background, environmental influences and the definition attached to normal occlusion.

PMID: 9313917 [PubMed - indexed for MEDLINE]

Evaluation of treatment and post-treatment changes by the PAR Index.

Eur J Orthod. 1997 Jun;19(3):279-88

Authors: Birkeland K, Furevik J, B&#xF8;e OE, Wisth PJ

To assess the outcome of orthodontic treatment, 224 cases treated in a postgraduate clinic were evaluated. Pre-treatment (T1), post-treatment (T2) and 5-year follow-up (T3) study casts were assessed by the Peer Assessment Rating (PAR) Index. The influence of various factors upon treatment and long-term outcome was analysed. According to the PAR Index, orthodontic treatment reduced the malocclusions on average by 76.7 per cent, and at follow-up the reduction was 63.8 per cent. Follow-up stability was good for 76.3 per cent of the cases. Some cases (4.0 per cent) even improved, while moderate to severe post-treatment relapse occurred in 19.7 per cent of the cases. Orthodontic treatment changed Angle Class I, II and III malocclusions to near ideal occlusion (PAR scores 4.4-6.8). No long-term interaction between the groups was discovered. Sex and extraction/non-extraction treatments did not significantly affect the results. The initial PAR score accounted for 77.8 per cent of the variation in treatment PAR score change (T1-T2), and for 61.8 per cent of the variation of long-term PAR score change (T1-T3). Age at treatment start accounted significantly for the variability of treatment changes (P < 0.001). The PAR score at the end of treatment had some explanatory importance (R2 = 0.099) for the long-term (T1-T3) result. However, PAR score changes in the follow-up period were difficult to predict.

PMID: 9239958 [PubMed - indexed for MEDLINE]

Glenoid fossa position in different facial types: a cephalometric study.

Br J Orthod. 1997 Feb;24(1):55-9

Authors: Baccetti T, Antonini A, Franchi L, Tonti M, Tollaro I

The purpose of the present study was to analyse the position of the glenoid fossa in subjects with different sagittal and vertical skeletal features. A cephalometric study was carried out on a sample of 180 subjects (90 males and 90 females, aged 7-12 years) who were combined to form three groups (60 subjects each) according to skeletal sagittal relationships and three groups (60 subjects each) according to skeletal vertical relationships. Cephalometric analysis comprised both sagittal and vertical measurements for the assessment of the position of the glenoid fossa in relation to surrounding skeletal structures. As for sagittal measurements, TMJ position was more posterior in skeletal Class II when compared with skeletal Class III. In the vertical plane, the position of the glenoid fossa relative to basicranial structures was more caudal in low angle subjects when compared with subjects with normal or high angle vertical relationships. Both basicranial structures and the posterior nasal spine may be used as reference structures for the assessment of vertical position of the glenoid fossa in diagnosis and treatment planning.

PMID: 9088604 [PubMed - indexed for MEDLINE]

A cephalometric evaluation of patients presenting with persistent digit sucking habits.

Br J Orthod. 1997 Feb;24(1):17-23

Authors: Moore MB, McDonald JP

Persistent digit sucking habits are an important aetiological factor for malocclusion, and patients with persistent habits are frequently referred for orthodontic treatment. The present study investigated the effects of digit sucking habits on vertical and anteroposterior dentofacial characteristics by employing a cephalometric analysis of patients with persistent digit sucking habits compared with patients without such habits. Significant differences were seen in maxillary prognathism, relative prognathism, maxillary incisor angulation, interincisal angle, maxillary length and maxillary plane angulation. No significant differences were observed for mandibular prognathism or length, maxillary mandibular plane angle, cranial base measurements nor any measurement of facial height. The digit sucking group were also found to have a larger variation of lower incisor angulation than the controls, although no significant difference in the mean value for this variable was detected. It is concluded that persistent digit sucking may cause largely dentoalveolar change, together with some minor effects on the skeletal pattern.

PMID: 9088599 [PubMed - indexed for MEDLINE]

Movements of the mandibular condyle kinematic center during jaw opening and closing.

J Dent Res. 1997 Feb;76(2):714-9

Authors: Yatabe M, Zwijnenburg A, Megens CC, Naeije M

Little is known about the detailed kinematics of the human temporomandibular condyle during jaw opening and closing. According to the rotate and swing model by Osborn (1989), the condyle is kept in close contact with the articular eminence during opening. Whether the condyle is in closer contact with the articular eminence during opening than during closing is unknown. Another consequence of the model is that the opening condylar movements are less variable than the closing movements. In this study, the hypothesis that the opening condylar path is closer to the articular eminence and also less variable than the closing condylar path is tested. Twenty subjects (10 males and 10 females with a mean age of 22) without signs or symptoms of a craniomandibular disorder performed 2 series of 4 protrusive movements and 2 series of 4 empty opening-closing movements. The movements were recorded by a six-degrees-of-freedom opto-electronic jaw movement recording system (OKAS-3D). The kinematic center of the condyle was used as a reference point for the reconstruction of condylar movement paths. Characteristics of the opening and closing paths were investigated by means of a displacement index (DI). This index is the quotient between the three-dimensional path length and the three-dimensional path distance between the start and the end point of an opening or closing movement of the kinematic center. The DI was smaller (p < 0.0001) and also less variable (p < 0.0001) during opening than during closing. The smaller DI value, in combination with the concave nature of the movement path, indicates that the opening path of the kinematic center lies above the closing path and thus closer to the articular eminence.

PMID: 9062566 [PubMed - indexed for MEDLINE]

Morphometry of the cranial base in subjects with Class III malocclusion.

J Dent Res. 1997 Feb;76(2):694-703

Authors: Singh GD, McNamara JA, Lozanoff S

The significance of the cranial base in the development of Class III malocclusion remains uncertain. The purpose of this study was to determine whether the form of the cranial base differs between prepubertal Class I and Class III subjects. Lateral cephalographs of 73 children of European-American descent aged between 5 and 11 years with Class III malocclusion were compared with those of their counterparts with a normal, Class I molar occlusion. The cephalographs were traced, checked, and subdivided into seven age- and sex-matched groups. Average geometries, scaled to an equivalent size, were generated based on 13 craniofacial landmarks by means of Procrustes analysis, and these configurations were statistically tested for equivalence. Bivariate and multivariate analyses utilizing 5 linear and angular measurements were undertaken to corroborate the Procrustes analysis. Graphical analysis, utilizing thin-plate spline and finite element methods, was performed for localization of differences in cranial base morphology. Results indicated that cranial base morphology differed statistically for all age-wise comparisons. Graphical analysis revealed that the greatest differences in morphology occurred in the posterior cranial base region, which generally consisted of horizontal compression, vertical expansion, and size contraction. The sphenoidal region displayed expansion, while the anterior regions showed shearing and local increases in size. It is concluded that the shape of the cranial base differs in subjects with Class III malocclusion compared with the normal Class I configuration, due in part to deficient orthocephalization, or failure of the cranial base to flatten during development.

PMID: 9062564 [PubMed - indexed for MEDLINE]

An investigation of tooth size in Northern Irish people with bimaxillary dental protrusion.

Eur J Orthod. 1996 Dec;18(6):617-21

Authors: McCann J, Burden DJ

This study examined tooth size in a sample of thirty Northern Irish people with bimaxillary dental protrusion. The mesiodistal diameters of all permanent teeth (excluding second and third molars) were measured. The tooth sizes were compared with a control group who did not have bimaxillary dental protrusion. The results revealed that, on average, tooth size for the overall maxillary and mandibular dentition was 5.7 per cent larger in the bimaxillary sample than in the control sample.

PMID: 9009425 [PubMed - indexed for MEDLINE]

Morphological associations between the Angle classes.

Eur J Orthod. 1996 Apr;18(2):111-8

Authors: Dibbets JM

The association between the Angle classification and craniofacial form has been analysed with the aid of multiple linear regression analysis in a sample of 170 children, before orthodontic treatment had started. It was found that part of the differences between Class II, Class I, and Class III was accounted for by systematical variation in a coherent set of midface and cranial base dimensions. These variations were in harmony with each other: the cranial base angle Ba-S-N closed and the legs S-N and S-Ba shortened systematically from Class II, over Class I, to Class III. The juvenile mandible notably was not systematically different. Because the cranial base provides the framework for the maxilla to be built upon, it is concluded that in juveniles the midface above anything else creates the characteristic difference between the three Angle classes, not the mandible. The Angle classification of malocclusion, therefore, represents three arbitrary markers on a morphological continuum.

PMID: 8670923 [PubMed - indexed for MEDLINE]

The kinematic center: a reference for condylar movements.

J Dent Res. 1995 Oct;74(10):1644-8

Authors: Yatabe M, Zwijnenburg A, Megens CC, Naeije M

The kinematic center of the temporomandibular condyle is that condylar point which follows as much as possible the same movement path during different types of mandibular movements. In this study, the location of the kinematic center with respect to the palpated lateral pole of the condyle was investigated. Also, the lengths of the condylar movement path reconstructed by means of the kinematic center and the palpated condyle were compared. Mandibular movements were recorded with 6 degrees of freedom in 20 healthy subjects. A software procedure calculated the location of the kinematic center as that mandibular point for which the protrusive and opening movement path showed a minimal difference. For each subject, its average location was calculated on the basis of 16 pairs of protrusive and opening movements. The kinematic center was located posteriorly and superiorly with respect to the palpated condylar point (p < 0.0001). The standard deviation in the anterior-posterior coordinate of the average kinematic center was smaller than that in the superior-inferior coordinate (p < 0.0001). During opening, the path length of the kinematic center is longer than that of the palpated lateral pole of the condyle (p < 0.0001). In contrast to left-right differences found in the path lengths of the lateral pole of the condyle, no left-right differences were found for the kinematic center.

PMID: 7499586 [PubMed - indexed for MEDLINE]