Magnitude and reproducibility of forces generated by clinicians during laceback placement.

J Orthod. 2006 Dec;33(4):270-5; discussion 256

Authors: Khambay BS, McHugh S, Millett DT

OBJECTIVE: To determine the magnitude and reproducibility of forces generated by clinicians during laceback placement using a force-measuring typodont. SETTING: An in vitro investigation. MATERIALS AND METHODS: An in vitro typodont model was developed, which incorporated strain gauges attached to a personal computer to allow measurement of the force generated on application of lacebacks. Ten operators were instructed to place lacebacks five times, on two separate occasions (T1 and T2). Inter-operator and intra-operator forces produced at T1 and T2 were compared. MAIN OUTCOME MEASURES: Forces generated by laceback placement. RESULTS: The forces generated by clinicians ranged from 0 to 11.1 N. There were significant differences in the mean forces generated by the different operators (P < 0.001), with differences between time points not being consistent across all operators (P < 0.001). Some operators were more consistent than others in the forces generated. CONCLUSION: In vitro, there was a large inter-operator variation in the forces produced during laceback placement. With the in vitro model used in this study, few operators applied similar forces when placing lacebacks on two separate occasions.

PMID: 17142333 [PubMed - indexed for MEDLINE]

Maxillary midline diastema: a case report involving a combined orthodontic/maxillofacial approach.

J Orthod. 2006 Mar;33(1):22-7

Authors: Campbell A, Kindelan J

This paper presents an orthodontic case of a large (14.5 mm) maxillary midline diastema that was related to the presence, and subsequent removal of 2 median maxillary supernumerary teeth and resulting bone loss. A combined orthodontic and maxillofacial approach involving bone grafting and fixed appliances was used to close the space. This episode of care was organized as interceptive treatment during development of the permanent dentition.

PMID: 16514130 [PubMed - indexed for MEDLINE]

Hypodontia in orthodontically treated children.

Eur J Orthod. 2005 Oct;27(5):457-60

Authors: Fekonja A

The frequency of hypodontia in orthodontically treated children, both male and female, and the association between tooth type, the upper or lower arch, the affected side and Angle's classification were studied using interviews, oral, study cast and panoramic radiographic examinations of 212 patients with a mean age of 12 years 7 months. A hypodontia frequency of 11.3 per cent was found for the total sample. This was higher than the incidence of hypodontia reported in other studies of orthodontically treated children. The most frequently missing teeth were the maxillary lateral incisors, and maxillary and mandibular second premolars. The missing teeth were more often absent on the right (54.2 per cent) than on the left (45.8 per cent) side, in both males and females. One tooth was absent in 29.2 per cent of patients, two in 58.5 per cent, but seldom three or more. Orthodontic space closure was the treatment of choice in 87.5 per cent of the subjects.

PMID: 16043466 [PubMed - indexed for MEDLINE]

Clinical evaluation of the centre of resistance of the upper incisors during retraction.

Eur J Orthod. 2005 Apr;27(2):196-201

Authors: T&#xFC;rk T, Elekdag-Türk S, Dinçer M

The aim of this study was to evaluate the movement of anterior teeth during retraction with a force applied through the assumed centre of resistance (CRe).Twenty-two subjects with a Class I or II malocclusion were included. Each subject had the two upper first premolars extracted, resulting in a symmetrical extraction space of at least 3 mm between the upper laterals and canines. The force was applied through the assumed CRe, located 9 mm gingival to the lateral tooth bracket. To examine the type of anterior tooth movement, 10 parameters were measured. A Wilcoxon test was used to determine the differences between pre- and post-retraction values, and a Mann-Whitney U-test to determine the mean differences between groups.In spite of the force application through the CRe, tipping of the anterior teeth was observed in 19 subjects and parallel movement in three patients. Consequently, the subjects were divided into two groups according to the location of the centre of rotation (CRo). In group 1 (nine cases), the CRo was located coronal to the root apex, and in group 2 (13 cases), apical to the root apex.Both groups showed a significant decrease in inclination (P < 0.01) and posterior crown movement (P < 0.01 for group 1 and P < 0.001 for group 2) of the anterior teeth. A significant posterior movement of the root apex was observed in group 2 (P < 0.001). Significant differences were found between the groups for anterior tooth inclination (P < 0.05) and root apex movement (P < 0.001). The reasons for these differences could not be conclusively determined.Even though experimental studies provide information regarding CRe location, factors such as bone support, root morphology and incisor inclination should be taken into consideration. The observation of tooth movement occurring during treatment and changes in treatment mechanics would be helpful in obtaining desired tooth movement.

PMID: 15817629 [PubMed - indexed for MEDLINE]

The effect of esthetic consultation methods on acceptance of diastema-closure treatment plan: a pilot study.

J Am Dent Assoc. 2004 Jul;135(7):875-81; quiz 1035-6, 1038

Authors: Almog D, Sanchez Marin C, Proskin HM, Cohen MJ, Kyrkanides S, Malmstrom H

BACKGROUND: The authors conducted a study to determine which of four consultation methods helped patients best understand a proposed treatment plan for maxillary anterior diastema closure. METHODS: The authors presented 24 subjects with four types of consultation in random order: before-and-after photographs of other patients, diagnostic models with wax setups, resin-based composite/esthetic preview/mock-ups and computer-imaging simulations. After viewing each method, the authors asked the subjects about treatment acceptability. At the end of the demonstrations of all four methods, the authors asked the subjects which consultation method helped them best understand the proposed treatment plan. RESULTS: A total of 87.5 percent of the subjects indicated that they would accept the proposed treatment plan after they were shown the computer-imaging simulation, 50 percent said they would after they were shown the resin-based composite/esthetic preview/mock-up, 41.7 percent said they would after they were shown photographs of other patients, and 25 percent said they would after they were shown diagnostic models with wax setups. When asked which method helped them best understand the proposed treatment, 54.2 percent of the subjects selected computer-imaging simulation, 33.3 percent selected resin-based composite/esthetic preview/mock-ups, and 12.5 percent selected before-and-after photographs of other patients. None of the subjects selected diagnostic models with wax setups. A chi2 test for goodness of fit indicated that these differences were statistically significant. CONCLUSION: Subjects preferred computer-imaging simulation to the other three consultation methods, and they indicated that computer-imaging simulation provided a better understanding of the proposed treatment plan for diastema closure. CLINICAL IMPLICATIONS: The use of computer-imaging simulation enhances the patient's understanding of a proposed treatment plan concerning maxillary anterior diastema closure.

PMID: 15354898 [PubMed - indexed for MEDLINE]

A clinical investigation of force delivery systems for orthodontic space closure.

J Orthod. 2003 Sep;30(3):229-36

Authors: Nightingale C, Jones SP

OBJECTIVE: To investigate the force retention, and rates of space closure achieved by elastomeric chain and nickel titanium coil springs. DESIGN: Randomized clinical trial. SETTING: Eastman Dental Hospital, London and Queen Mary's University Hospital, Roehampton, 1998-2000. Subjects, materials and methods: Twenty-two orthodontic patients, wearing the pre-adjusted edgewise appliance undergoing space closure in opposing quadrants, using sliding mechanics on 0.019 x 0.025-inch posted stainless steel archwires. Medium-spaced elastomeric chain [Durachain, OrthoCare (UK) Ltd., Bradford, UK] and 9-mm nickel titanium coil springs [OrthoCare (UK) Ltd.] were placed in opposing quadrants for 15 patients. Elastomeric chain only was used in a further seven patients. The initial forces on placement and residual forces at the subsequent visit were measured with a dial push-pull gauge [Orthocare (UK) Ltd]. Study models of eight patients were taken before and after space closure, from which measurements were made to establish mean space closure. MAIN OUTCOME MEASURES: The forces were measured in grammes and space closure in millimetres. RESULTS: Fifty-nine per cent (31/53) of the elastomeric sample maintained at least 50 per cent of the initial force over a time period of 1-15 weeks. No sample lost all its force, and the mean loss was 47 per cent (range: 0-76 per cent). Nickel titanium coil springs lost force rapidly over 6 weeks, following that force levels plateaued. Forty-six per cent (12/26) maintained at least 50 per cent of their initial force over a time period of 1-22 weeks, and mean force loss was 48 per cent (range: 12-68 per cent). The rate of mean weekly space closure for elastomeric chain was 0.21 mm and for nickel titanium coil springs 0.26 mm. There was no relationship between the initial force applied and rate of space closure. None of the sample failed during the study period giving a 100 per cent response rate. CONCLUSIONS: In clinical use, the force retention of elastomeric chain was better than previously concluded. High initial forces resulted in high force decay. Nickel titanium coil springs and elastomeric chain closed spaces at a similar rate.

PMID: 14530421 [PubMed - indexed for MEDLINE]

A randomized clinical trial to compare three methods of orthodontic space closure.

J Orthod. 2002 Mar;29(1):31-6

Authors: Dixon V, Read MJ, O'Brien KD, Worthington HV, Mandall NA

AIM: To compare the rates of orthodontic space closure for: Active ligatures, polyurethane powerchain (Rocky Mountain Orthodontics, RMO Europe, Parc d'Innovation, Rue Geiler de Kaysersberg, 67400 Illkirch-Graffenstaden, Strasbourg, France) and nickel titanium springs. SAMPLE: Patients entering the space closure phase of fixed orthodontic treatment attending six orthodontic providers. Twelve patients received active ligatures (48 quadrants), 10 patients received powerchain (40 quadrants) and 11 patients, nickel-titanium springs (44 quadrants). METHOD: Patients were randomly allocated for treatment with active ligatures, powerchain or nickel titanium springs. Upper and lower study models were collected at the start of space closure (T(o)) and 4 months later (T(1)). We recorded whether the patient wore Class II or Class III elastics. Space present in all four quadrants was measured, by a calibrated examiner, using Vernier callipers at T(o) and T(1.) The rate of space closure, in millimetres per month (4 weeks) and a 4-monthly rate, was then calculated. Examiner reliability was assessed at least 2 weeks later. RESULTS: Mean rates of space closure were 0.35 mm/month for active ligatures, 0.58 mm/month for powerchain, and 0.81 mm/month for NiTi springs. No statistically significant differences were found between any methods with the exception of NiTi springs showing more rapid space closure than active ligatures (P < 0.05). There was no effect of inter-arch elastics on rate of space closure. CONCLUSIONS: NiTi springs gave the most rapid rate of space closure and may be considered the treatment of choice. However, powerchain provides a cheaper treatment option that is as effective. The use of inter-arch elastics does not appear to influence rate of space closure.

PMID: 11907307 [PubMed - indexed for MEDLINE]

Hypodontia, ankylosis and infraocclusion: report of a case restored with a fibre-reinforced ceromeric bridge.

Br Dent J. 2001 Dec 8;191(11):613-6

Authors: Sidhu HK, Ali A

Retained primary molars without permanent successors often undergo progressive infra-occlusion, without predictable exfoliation. Early prophylactic removal, after assessment of root resorption and adjacent periodontal support loss as well as age of onset, is often indicated. This article describes the joint orthodontic-restorative care of such a case and describes an alternative method of restoration using a fibre-reinforced ceromeric bridge. As well as a conservative preparation and good aesthetics, an overlay restoration provided a fully functional occlusion.

PMID: 11770947 [PubMed - indexed for MEDLINE]

The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment.

Eur J Orthod. 2000 Dec;22(6):697-710

Authors: Robertsson S, Mohlin B

Orthodontic treatment for patients with uni- or bilateral congenitally missing lateral incisors is a challenge to effective treatment planning. The two major alternatives, orthodontic space closure or space opening for prosthetic replacements, can both compromise aesthetics, periodontal health, and function. The aim of this retrospective study was to examine treated patients who had congenitally missing lateral incisors and to compare their opinion of the aesthetic result with the dentists' opinions of occlusal function and periodontal health. In this sample, 50 patients were identified. Thirty had been treated with orthodontic space closure, and 20 by space opening and a prosthesis (porcelain bonded to gold and resin bonded bridges). The patient's opinion of the aesthetic result was evaluated using the Eastman Esthetic Index questionnaire and during a structured interview. The functional status, dental contact patterns, periodontal condition, and quality of the prosthetic replacement was evaluated. In general, subjects treated with orthodontic space closure were more satisfied with the appearance of their teeth than those who had a prosthesis. No significant differences in the prevalence of signs and symptoms of temporomandibular dysfunction (TMD) were found. However, patients with prosthetic replacements had impaired periodontal health with accumulation of plaque and gingivitis. The conclusion of this study is that orthodontic space closure produces results that are well accepted by patients, does not impair temporomandibular joint (TMJ) function, and encourages periodontal health in comparison with prosthetic replacements.

PMID: 11212605 [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]

Management of missing maxillary lateral incisors.

J Am Dent Assoc. 1999 Jan;130(1):80-4

Authors: Sabri R

BACKGROUND: Missing maxillary lateral incisors create an esthetic problem with specific orthodontic and prosthetic considerations. The purpose of this article is to describe treatment protocols and problems encountered in the management of this disorder. CASE DESCRIPTION: The two common treatment options are orthodontic space opening for future restorations or orthodontic space closure using canines to replace the missing maxillary lateral incisors. The required amount of space opening and the various prosthetic options are discussed. The methods for reshaping canines in orthodontic space closure and building them up to simulate lateral incisors also are described. The indications, advantages and disadvantages of both treatment modalities are outlined to help clinicians make decisions in borderline situations. CLINICAL IMPLICATIONS: Teamwork between the orthodontist, general practitioner and restorative dentist is important when analyzing factors related to individual patients and establishing overall treatment plans. This also will allow treatment modalities and the various options for replacing missing maxillary lateral incisors in space opening to be discussed between team members and the patient.

PMID: 9919035 [PubMed - indexed for MEDLINE]

Forceps extraction of teeth with severe internal root resorption.

J Am Dent Assoc. 1997 Jun;128(6):751-4

Authors: Javaheri DS, Garibaldi JA

Many treatment plans require a dental practitioner to maintain the entire labial cortical plate of bone when removing an anterior maxillary tooth. A tooth with an undermined root secondary to an endodontic perforation or internal (Idiopathic) resorption can present a surgical challenge to the general practitioner. This article describes a new technique for extracting a severely undermined anterior maxillary tooth while maintaining the entire labial cortex of bone.

PMID: 9188233 [PubMed - indexed for MEDLINE]

An investigation into the placement of force delivery systems and the initial forces applied by clinicians during space closure.

Br J Orthod. 1997 May;24(2):127-31

Authors: Nattrass C, Ireland AJ, Sherriff M

This in vitro investigation was designed to establish not only how clinicians apply forces for space closure when using the straight wire appliance and sliding mechanics, but also to quantify the initial force levels produced. A single typodont, with residual extraction space in each quadrant, was set up to simulate space closure using sliding mechanics. On two occasions, at least 2 months apart, 18 clinicians were asked to apply three force delivery systems to the typodont, in the manner in which they would apply it in a clinical situation. The three types of force delivery system investigated were elastomeric chain, an elastomeric module on a steel ligature, and a nickel-titanium closed coil spring. A choice of spaced or unspaced elastomeric chain produced by a single manufacturer was provided. The amount of stretch which was placed on each type of system was measured and, using an Instron Universal Testing Machine, the initial force which would be generated by each force delivery system was established. Clinicians were assessed to examine their consistency in the amount of stretch which each placed on the force delivery systems, their initial force application and their ability to apply equivalent forces with the different types of force delivery system. The clinicians were found to be consistent in their method of application of the force delivery systems and, therefore, their force application, as individuals, but there was a wide range of forces applied as a group. However, most clinicians applied very different forces when using different force delivery systems. When using the module on a ligature the greatest force was applied, whilst the nickel titanium coil springs provided the least force.

PMID: 9218110 [PubMed - indexed for MEDLINE]

A post-treatment evaluation of multibonded ceramic brackets in orthodontics.

Eur J Orthod. 1997 Apr;19(2):219-28

Authors: Artun J

The purpose of this study was to perform a clinical evaluation of ceramic brackets with silane-coated bases for chemical (Transcend) and microcrystalline bases for mechanical (Transcend 2000) retention. The sample consisted of 49 consecutive patients; the first 30 were treated with brackets with chemical retention and the following 19 with brackets with mechanical retention. For each patient the brackets on one side of the mouth were assigned at random to be bonded with Concise and the other with Transbond as recommended by the manufacturers. Levelling and alignment of severely displaced roots was initiated with superelastic wires and completed with stainless steel wires. Any space closure or correction of interarch discrepancy was performed with rectangular stainless steel wires. The brackets with chemical retention were removed with a torsional rotation debonding wrench, and those with mechanical retention with a tensile debonding plier. The bond failure rate was low, with no difference between the two bracket types or between brackets bonded with Concise and Transbond. Bracket fracture was a significant clinical problem, both during active treatment and at the time of appliance removal. New teeth with formation of pronounced enamel cracks were seen in 20.6 and 10.5 per cent of the teeth treated with brackets with chemical and mechanical retention, respectively (P < 0.001), with no difference between teeth bonded with Concise and Transbond. Enamel tear-outs were seen in 3 of the 544 and in 1 of the 344 teeth treated with the respective types of bracket. These teeth were bonded with Concise.

PMID: 9183072 [PubMed - indexed for MEDLINE]