Complete denture impression techniques: evidence-based or philosophical.

Indian J Dent Res. 2007 Jul-Sep;18(3):124-7

Authors: Singla S

Code of practice is dangerous and ever-changing in today's world. Relating this to complete denture impression technique, we have been provided with a set of philosophies--"no pressure, minimal pressure, definite pressure and selective pressure". The objectives and principles of impression-making have been clearly defined. Do you think any philosophy can satisfy any operator to work on these principles and achieve these objectives? These philosophies take into consideration only the tissue part and not the complete basal seat, which comprises the periphery, the tissues and the bone structure. Under such circumstances, should we consider a code of practice dangerous or should we develop an evidence-based approach having a scientific background following certain principles, providing the flexibility to adapt to clinical procedures and to normal biological variations in patients rather than the rigidity imposed by strict laws?

PMID: 17687175 [PubMed - indexed for MEDLINE]

Disinfection efficiency of irreversible hydrocolloid impressions using different concentrations of sodium hypochlorite: a pilot study.

J Contemp Dent Pract. 2007;8(4):27-34

Authors: Memarian M, Fazeli MR, Jamalifar H, Azimnejad A

AIM: Dental impressions are potential sources of bacterial contamination which could eventually lead to transmissible infectious diseases through the blood or saliva. Sodium hypochlorite is an effective disinfectant recommended by the American Dental Association (ADA) in a 1:10 dilution for a ten minute immersion to disinfect irreversible hydrocolloid impressions. As the ADA protocol is sometimes neglected in busy practice settings, this pilot study was designed to determine an efficient and effective protocol for disinfection of irreversible hydrocolloid impressions. METHODS AND MATERIALS: Various concentrations of sodium hypochlorite and disinfection times were challenged against irreversible hydrocolloid impressions contaminated with six Gram-positive and Gram-negative bacteria. RESULTS: A two minute immersion time in a 0.6% solution of sodium hypochlorite protocol was found to prevent bacterial growth on the impressions. CONCLUSION: Disinfection of irreversible hydrocolloid impressions in a 0.6% solution of sodium hypochlorite for two minutes was as effective as the ADA's protocol of using a 0.5% sodium hypochlorite solution for ten minutes to destroy the test bacteria.

PMID: 17486184 [PubMed - indexed for MEDLINE]

Making fixed prostheses that are not too high.

J Am Dent Assoc. 2006 Jan;137(1):96-8

Authors: Christensen GJ

It has been observed that a high percentage of multiple crowns or FPDs arrive from laboratories too "high." This article suggests methods to create accurate alginate impressions, opposing casts and IORs. If dentists use these techniques, it is anticipated that fewer FPDs will be too high as dentists attempt to seat them in the mouth.

PMID: 16457005 [PubMed - indexed for MEDLINE]

Special tray design questioned.

Br Dent J. 1999 Dec 11;187(11):578; author reply 578

Authors: Walter JD

PMID: 16163273 [PubMed - indexed for MEDLINE]

Modification of a metal stock tray for a polyvinylsiloxane impression.

J Am Dent Assoc. 2005 Aug;136(8):1138-9

Authors: Haubenreich JE, Osborne PB

PMID: 16161369 [PubMed - indexed for MEDLINE]

[The effect of disinfection on dimension stability of impressions]

Shanghai Kou Qiang Yi Xue. 2004 Aug;13(4):290-2

Authors: Lu JX, Zhang FM, Chen YM, Qian M

PURPOSE: To measure the effect of disinfection on dimension stability of alginate, hydrocolloid, and Express putty impressions which were separately immersed in 2% glutaraldehyde solution and 1% 84 disinfector. METHODS: Alginate, hydrocolloid, and Express putty impressions were made by 20 mm x 20 mm x 40 mm standards test wares. There were 45 in each kind of test wares. They were divided into 9 groups and 5 pieces in every group. Among them, one group using clear water to flush acted as the matched control, the other groups received respectively 2% glutaraldehyde solution and 1% 84 disinfector immersed in 10 minutes, 20 minutes, 30 minutes. After two hours, the spiral instrument was used to measure the model. The experiment data were analyzed by using the SPSS 11.0 statistic software package. RESULTS: There was no significant difference in pure water flush and spraying treatment respectively. There was significant difference for alginate and hydrocolloid impression was immersed before and after. There was no significant difference for Express putty silicon rubber impression materials before and after immersion. There was no significant difference in 2% glutaraldehyde solution and 1% 84 disinfector when impressions were immersed in. CONCLUSION: Alginate, hydrocolloid and Express putty impressions immersed in 2% glutaraldehyde solution and 1% 84 disinfector separately for 20 minutes does not affect the accuracy, and can be used clinically.

PMID: 15349668 [PubMed - indexed for MEDLINE]

An accurate system of serially recording anterior open bite using a modified technique for impression taking and study model construction.

J Orthod. 2004 Mar;31(1):9-12

Authors: Kyi CS, Mars M

A simple impression technique is described that enables the clinician to record an anterior open bite, to provide accurate study model construction, and to monitor the anterior open bite. A case is presented that illustrates this technique with subsequent monitoring over an 8-year period

PMID: 15071144 [PubMed - indexed for MEDLINE]

The influence of handling on the elasticity of addition silicone putties.

Pesqui Odontol Bras. 2003 Jul-Sep;17(3):254-60

Authors: Rodrigues Filho LE, Muench A, Francci C, Luebke AK, Traina AA

The handling of vinyl polysiloxane (addition silicone) impression putties with latex gloves is said to interfere with the setting of these impression materials. The aim of this study is to evaluate the effect of handling techniques on the setting of vinyl polysiloxane impression putties using several types of gloves. The setting of these materials was evaluated by means of an elasticimeter. Four vinyl polysiloxane putty impression materials and five brands of gloves (one made of vinyl, one of synthetic rubber, and three of natural rubber) were studied. Based on the type of glove, they were previously washed or not, and a spatula was used or not for initial mixing (before handmixing). The vinyl, the synthetic and one of the natural rubber gloves did not require the previous washing procedure and/or the use of a spatula for initial mixing. Two other natural rubber gloves - depending on the silicone -, showed satisfactory results only when the initial mixing was performed with a spatula. It was concluded that setting inhibition depends on the kind of vinyl polysiloxane impression material and the kind of gloves used, but when the initial mixing was performed with the spatula this setting inhibition was overcome. The results of this study also showed that it is possible to associate cross-contamination control and satisfactory performance of addition silicone putty materials. When doubts arise from the compatibility between vinyl polysiloxane impression putties and gloves, the initial mixing should be performed with a spatula.

PMID: 14762504 [PubMed - indexed for MEDLINE]

Have fixed-prosthodontic impressions become easier?

J Am Dent Assoc. 2003 Aug;134(8):1121-3

Authors: Christensen GJ

Excellent fixed-prosthodontic impressions are ensured with the presence of healthy soft tissue, atraumatic tooth and soft-tissue preparation, use of packing cords when indicated, routine use of astringents and taking enough time to accomplish the preimpression procedures thoroughly. Currently advertised products that supposedly eliminate the difficulty of fixed-prosthodontic impressions and the need for cords have decreased some of the frustrations of impression making, but the challenge remains. Excellent impressions require accurate and stable impression materials, time, conscientious and thorough techniques, attention to every detail, good support staff and a working knowledge of all aspects of the concepts involved.

PMID: 12956356 [PubMed - indexed for MEDLINE]

Accuracy of a system for creating 3D computer models of dental arches.

J Dent Res. 2003 Jun;82(6):438-42

Authors: DeLong R, Heinzen M, Hodges JS, Ko CC, Douglas WH

Three-dimensional imaging of dental tissues will have a major impact in dentistry if the images are accurate. The purpose of this study was to measure the accuracy and precision of a system for creating three-dimensional images of dental arches. Using vinyl polysiloxane impression materials and improved dental stone, we made 10 stone casts of a "dental" standard with known dimensions. The impressions and casts were scanned by means of a Comet 100 optical scanner. Custom software created three-dimensional images (computer models) from the scanned data. Accuracy was defined as the average of the absolute differences between the computer models and the standard. Precision was the standard deviation of accuracy over 10 repeated measures. Software processing improved the accuracy of the scanner data. Accuracy +/- precision for the casts and impressions was 0.024 +/- 0.002 mm and 0.013 +/- 0.003 mm, respectively. The system produced computer models with sufficient accuracy for clinical application.

PMID: 12766195 [PubMed - indexed for MEDLINE]

How to make a good impression (crown and bridge).

Br Dent J. 2001 Oct 13;191(7):402-3, 405

Authors: Millar B

PMID: 11697602 [PubMed - indexed for MEDLINE]

An evaluation of occlusal contact marking indicators. A descriptive quantitative method.

J Am Dent Assoc. 2001 Sep;132(9):1280-6; quiz 1319

Authors: Millstein P, Maya A

BACKGROUND: Dentistry needs an accurate means of recording occlusal contacts. The authors undertook a study to evaluate the accuracy of occlusal contact marking indicators and the reproducibility of their results. METHODS: The authors recorded occlusal contact areas using occlusal indicators made of paper, film and silk. They studied 10 indicators by testing them on articulator-mounted, impact-resistant casts and measuring the surface area of the resultant contact marks made on impact using a video camera, a frame grabber and a computer-linked image analyzer. RESULTS: All indicators differed in surface area markings between and within groups. The indicator's thickness and color and the material from which it was made separately and interactively had an effect on the size of the markings. Measurements were evaluated at a P = .05 significance level. The authors used Bonferroni-adjusted cutoffs when computing post hoc pairwise comparisons. The data were grouped into four categories: descriptive statistics, comparison of indicators by surface area marked, indicator thickness and repeatability. CONCLUSIONS: Indicators vary, and their markings may not be repeatable even when they are used alike. Further study is required, as is the development of an indicator measuring standard. CLINICAL IMPLICATIONS: Indicators are used to determine occlusal disharmony and to establish occlusal harmony. Since the accuracy of the markings can be questioned, the interpretation of the markings may be correct but the accuracy of the markings themselves may be misleading.

PMID: 11665355 [PubMed - indexed for MEDLINE]

A method for removing a fractured resin post and core pattern.

J Am Dent Assoc. 2001 Mar;132(3):337-8

Authors: Haselton DR, Diaz-Arnold AM

PMID: 11258090 [PubMed - indexed for MEDLINE]

Evaluation of a reproduction technique for the study of the enamel composite/bracket base area.

J Orthod. 2000 Sep;27(3):261-6

Authors: Wilner FJ, Oliver RG

The objective of the study was to evaluate a reproduction method that would enable the study of the enamel/ bracket/composite interface in vivo, and consisted of in vitro assessment of two different impression materials to compare reproduction of brackets bonded to extracted teeth followed by in vivo assessment of the superior material. In vitro standard edgewise brackets were bonded to two extracted teeth and impressions were taken using two different types of low viscosity silicone-based impression materials. A medium viscosity silicone impression material was used to support the original impression. Three impressions of both the gingival and occlusal aspect of the bracket base region were obtained using each of the impression materials. Replicas were then prepared for SEM viewing and these compared to SEMs of the real teeth for reproduction of detail. A 3-point Reproducibility Index was used to compare the SEM photographs of the comparable replicas. One impression material was clearly superior to the other and produced an acceptably accurate representation of the true clinical situation in three out of four samples. This material also performed well in the in vivo situation. The technique described is satisfactory for the production and analysis of SEM pictures of the enamel/composite/ bracket base interface in vivo.

PMID: 11099559 [PubMed - indexed for MEDLINE]

Minimizing excessive composite resin when fabricating fiber-reinforced splints.

J Am Dent Assoc. 2000 Jul;131(7):977-9

Authors: Hughes TE, Strassler HE

PMID: 10916335 [PubMed - indexed for MEDLINE]

Disinfection and communication practices: a survey of U.S. dental laboratories.

J Am Dent Assoc. 2000 Jun;131(6):786-92

Authors: Kugel G, Perry RD, Ferrari M, Lalicata P

BACKGROUND: The need to disinfect impressions is crucial to prevent the transmission of infectious diseases. The authors report the results of a survey of U.S. dental laboratory directors. The survey was designed to determine how well dental laboratory personnel are communicating with dentists regarding the disinfection of impressions, and, in turn, what laboratory technicians are doing to protect themselves against microbial cross-contamination. METHODS: Four hundred dental laboratory directors were selected in a blinded and random manner. To create a geographically representative sample, an equal number of laboratory directors from the East, Midwest and West were interviewed. A survey consisting of 16 open-ended questions was conducted by trained interviewers via 10- to 15-minute telephone interviews. All dental laboratory directors stated that they were thoroughly familiar with their laboratory's disinfection protocol. RESULTS: The survey documented that the majority of impressions were made of polyvinyl (57 percent) or polyether (27 percent) materials. Only 44 percent of the respondents stated that they knew if the impressions they received had been disinfected. Twenty-three percent of the laboratory directors did not know the method of disinfection used, and 47 percent did not know the length of time involved. Forty-five percent of the respondents reported that they receive inadequate instruction in regard to disinfection techniques. No one class of impression materials was found to be more problematic than others by the laboratory directors. CONCLUSIONS: The results indicate a significant and problematic lack of communication between these team members. The responses also suggested that laboratory-perceived problems with impressions were not linked to any particular type of material, but more to the disinfection technique used. PRACTICE IMPLICATIONS: Lack of communication between dentists, staff members and dental laboratory personnel, along with poor training of laboratory personnel in disinfection techniques, may have a direct effect on the prosthetic results achieved in dental practices.

PMID: 10860331 [PubMed - indexed for MEDLINE]

The altered cast impression technique revisited.

J Am Dent Assoc. 1999 Oct;130(10):1476-81

Authors: Feit DB

BACKGROUND: The altered cast impression technique of fabricating removable partial dentures, originally described more than 60 years ago, improves the residual-ridge-to-dentition relationship of the prosthesis. This potentially increases patient satisfaction while preserving the remaining supporting structures. LITERATURE REVIEWED: This article reviews research that evaluated abutment tooth movement as a result of the relationship of the denture base to the residual ridge, revealing that improved fit reduced tooth movement. Load distribution studies have shown that a well-fitting denture base distributes stresses favorably to the supporting bone and abutment teeth. Other studies showing that increased residual ridge coverage coupled with a well-fitting denture base reduces stress per unit area, potentially preserving the remaining supporting structures. CASE DESCRIPTION: The article describes a patient who had a unilateral distal extension removable partial denture that was fabricated after the failure of a 20-year-old partial denture due to extensive dental decay. The prosthesis was fabricated over the course of four appointments, and the prosthesis was delivered on the fifth appointment. The patient, who wears the prosthesis daily, expressed comfort and ease of use at a one-year recall examination. CLINICAL IMPLICATIONS: Distal extension edentulism can affect a patient's ability to function as a dentate person. A well-made removable partial denture that has appropriate extensions, borders and ridge-to-dentition relationship will benefit the partially edentulous patient by providing increased comfort and improved dental function.

PMID: 10570592 [PubMed - indexed for MEDLINE]

A technique that saves impression material.

J Am Dent Assoc. 1999 Aug;130(8):1202

Authors: Barr MI

PMID: 10491932 [PubMed - indexed for MEDLINE]

Using orthodontic wax to create a diagnostic cast.

J Am Dent Assoc. 1999 May;130(5):743

Authors: Brooks SA

PMID: 10332141 [PubMed - indexed for MEDLINE]

An impression technique for severely resorbed mandibles in geriatric patients.

J Am Dent Assoc. 1999 Feb;130(2):255-6

Authors: Pyle MA

PMID: 10036849 [PubMed - indexed for MEDLINE]

Using an old technique with modern materials to fabricate esthetic temporary restorations.

J Am Dent Assoc. 1999 Jan;130(1):99-100

Authors: Gottlieb MM

PMID: 9919037 [PubMed - indexed for MEDLINE]

Rheological properties of elastomeric impression materials before and during setting.

J Dent Res. 1998 Nov;77(11):1874-80

Authors: McCabe JF, Arikawa H

In this study, we examined the rheological properties of elastomeric impression materials, both before and during setting, to assess the clinical significance of certain key characteristics such as viscosity, pseudoplasticity, and the rate of development of elasticity. The hypothesis to be tested was that monitoring the change in tan delta is the most appropriate means of monitoring the setting characteristics of elastomers. The loss tangent (tan delta) and the dynamic viscosity (eta') for five impression materials (both unmixed pastes and mixed/setting materials) were measured by means of a controlled-stress rheometer in a cone/plate configuration. For unmixed pastes, tests were performed at various frequencies (0.1 to 10 Hz) and torques (from 1 to 50 x 10(-4) Nm), while testing on setting materials was performed at constant frequency (1 Hz) and torque (3 x 10(-3) Nm). Most base and catalyst pastes were pseudoplastic before being mixed. Immediately after being mixed, the polyether (tan delta = 9.85) and polysulfide (tan delta = 9.54) elastomers showed tan delta markedly higher than those of other mixed materials (tan delta = 4.96 to 3.01). The polyvinylsiloxane elastomers showed lower initial tan delta, which rapidly reduced even further with time. This suggests that these materials should be used as soon as possible after being mixed. The polyether elastomer had a comparatively long induction period during which the tan delta remained at a high value. These characteristics are thought to be key factors in controlling clinical efficacy and therefore support the hypothesis that monitoring tan delta is an appropriate method for evaluating the setting characteristics of elastomers. One limitation was that the controlled-stress rheometer was unable to monitor rheological properties through to completion of setting.

PMID: 9823725 [PubMed - indexed for MEDLINE]

Simplifying dual-arch impressions.

J Am Dent Assoc. 1998 Nov;129(11):1599-600

Authors: Imbery TA

PMID: 9818578 [PubMed - indexed for MEDLINE]

The effects of different storage conditions on polyether and polyvinylsiloxane impressions.

J Am Dent Assoc. 1998 Jul;129(7):1014-21

Authors: Purk JH, Willes MG, Tira DE, Eick JD, Hung SH

While being shipped to a laboratory, impressions can be exposed to excessive temperatures. This study compared the effects of different time and temperature storage conditions, including temperature extremes of 66 C and -10 C, on the accuracy of addition silicone and polyether impressions. The greatest distortion generally occurred as a result of the 66 C temperature extreme. The authors recommend that impressions be poured in stone according to manufacturers' specifications before being shipped to a dental laboratory.

PMID: 9685767 [PubMed - indexed for MEDLINE]

Impression materials.

Br J Orthod. 1998 May;25(2):133-40

Authors: Doubleday B

This paper incorporates a brief review of impression materials currently available for use by the orthodontic profession; subjective assessments of a selection of alginates, silicones and bite registration materials in a clinical setting; and a list of prices and retailers of impression materials.

PMID: 9668998 [PubMed - indexed for MEDLINE]

Vogele-Bale-Hohner mouthpiece: registration device for frameless stereotactic surgery.

Radiology. 1998 Jul;208(1):261-5

Authors: Martin A, Bale RJ, Vogele M, Gunkel AR, Thumfart WF, Freysinger W

PMID: 9646822 [PubMed - indexed for MEDLINE]

A 30-minute in-office indirect composite inlay technique.

J Am Dent Assoc. 1998 Mar;129(3):366-7

Authors: Settembrini L, Gultz G, Scherer W, Kaim J

PMID: 9529814 [PubMed - indexed for MEDLINE]

An alternative for making master impressions for complete dentures.

J Am Dent Assoc. 1997 Oct;128(10):1436-7

Authors: Loh PL

PMID: 9332145 [PubMed - indexed for MEDLINE]

Trouble-shooting dual arch impressions II.

J Am Dent Assoc. 1997 Sep;128(9):1277-81

Authors: Kaplowitz GJ

Dual arch impression procedures can produce accurate impressions and bite registrations for the fabrication of single crowns. To accomplish this, the dentist must select an appropriately sized and shaped tray, appropriate impression material and a dual arch impression procedure suitable for each case. Dual arch impression procedures can save impression material and chair time.

PMID: 9297950 [PubMed - indexed for MEDLINE]

What category of impression material is best for your practice?

J Am Dent Assoc. 1997 Jul;128(7):1026-8

Authors: Christensen GJ

PMID: 9231610 [PubMed - indexed for MEDLINE]

Comparing the accuracy of reversible hydrocolloid and elastomeric impression materials.

J Am Dent Assoc. 1997 Feb;128(2):183-8

Authors: Federick DR, Caputo A

This in vitro investigation evaluated the accuracy of reversible hydrocolloid, vinyl polysiloxane and polyether elastic impression materials used in conjunction with two die stones. The authors made impressions in an experimental environment that approximated clinical conditions in regard to temperature and moisture. Analysis of variance and t-tests were used to compare corresponding measurements on experimental casts made from the various impression materials.

PMID: 9037971 [PubMed - indexed for MEDLINE]

Making impressions in just 90 seconds.

J Am Dent Assoc. 1996 Oct;127(10):1530

Authors: Kaplowitz GJ

PMID: 8908924 [PubMed - indexed for MEDLINE]

Foreign body aspiration in dentistry: a review.

J Am Dent Assoc. 1996 Aug;127(8):1224-9

Authors: Cameron SM, Whitlock WL, Tabor MS

This article reviews the dangers of aspirating foreign bodies of dental origin. Two illustrative cases are presented, including an unusual case involving aspiration of an elastomeric impression material. The authors describe the techniques used to identify the foreign body. A radiodensimetric study of four impression materials demonstrates the difficulty of identifying most impression materials. The authors also present some strategies for reducing the risk of aspiration during dental procedures.

PMID: 8803399 [PubMed - indexed for MEDLINE]

Form difference computations in restorative dentistry utilizing the macroelement method.

J Dent Res. 1996 Jul;75(7):1464-76

Authors: McAlarney ME, Phillips CB, Song D

The comparison between the size and shape (form) of two structures or the analysis of one object under differing conditions is important in restorative dentistry. Despite rapid advances in digitizing technologies, form comparison is still mainly limited to scalar measurements. The objective of this study was to test the potential use of a newly developed tensorial morphometric difference technique, the macroelement method, in a model restrative system where the processing and materials properties are known duplication of a denture anchor in stone via polysulfide, addition silicone, and polyether impression materials. Nine machined landmarks were utilized to construct a nine-sided element for macroelement analysis. Macroelement results compared well with the known impression materials properties of polymerization shrinkage and incomplete recovery in terms of: (1) larger die diameter, (2) smaller die (vertically), (3) horizontal direction of maximum expansion, and (4) vertical direction of maximum contraction. Also, macroelement results along boundary lines were equal to the traditional form difference measure of change in length/length of those lines. The macroelement method provided results which are superior to those of traditional methods in that both (1) the magnitude and direction of difference at any point on the structure could be determined, and (2) the graphical representation of the results provides an intuitive appreciation of how and where the forms differ Therefore, since macroelement results: (1) compare well with known materials properties and traditional measures, and (2) have the above-stated advantages, tensorial techniques such as the macroelement method, used in conjunction with new digitizing technologies, can be used better to describe the kinematics of form difference. With the description of the kinematics provided by the technique, the dynamic cause of the form difference can be ascertained with the investigators knowledge of materials. The investigators can then suggest changes to be made in materials and/or techniques that would enable the desired size and shape to be obtained.

PMID: 8876598 [PubMed - indexed for MEDLINE]

Constructing direct porcelain laminate veneer provisionals.

J Am Dent Assoc. 1995 May;126(5):653-6

Authors: Kurtz KS

Historically, teeth prepared for indirect restorations are protected by some type of provisional restoration. This is not always the case for teeth prepared for porcelain laminate veneers because construction of temporaries can be time-consuming. This case report illustrates a quick technique for fabricating a direct composite veneer provisional for teeth prepared for porcelain laminate veneers.

PMID: 7759691 [PubMed - indexed for MEDLINE]

The effect of particle size reduction on the jaw gape in human mastication.

J Dent Res. 1991 May;70(5):931-7

Authors: Van der Bilt A, Van der Glas HW, Olthoff LW, Bosman F

Eight subjects participated in chewing experiments to examine how the jaw gape in consecutive chewing cycles depends on the dimensions and the volume of the food bolus. Different volumes of chewing-gum and a silicone rubber (Optosil) were used. The initial particle size of Optosil was also varied. With the aid of a sieving procedure, the size distribution of Optosil particles was determined after different numbers of chewing cycles. The maximum size of a chewing-gum bolus along three orthogonal axes was determined after a random number of chewing cycles for all the volumes of chewing-gum offered. The jaw gape was measured by means of an optical motion analysis system and calibrated at the level of the first molars. The maximum jaw gape and the gape at the first fall in mandibular velocity after the onset of jaw-closing were determined for different chewing cycles from the position signal and its time derivative. For each volume of chewing gum offered to the subject, the average of the maximum gapes attained in the subsequent cycles of jaw movement was related to the characteristic height of a bolus of that volume; maximum velocity of closing appeared to occur while the antagonistic teeth were already penetrating the gum bolus. The increase in the maximum jaw gape, the gape at the velocity maximum, and the height of the gum bolus, as a function of the volume of chewing-gum, could be well-described by a power function of the volume. The exponent of the power function for both jaw gapes was only slightly smaller than the exponent obtained for the bolus height.(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 2022777 [PubMed - indexed for MEDLINE]

Onset of elasticity in setting elastomers.

J Dent Res. 1990 Sep;69(9):1573-5

Authors: McCabe JF, Carrick TE

A controlled stress-rheometer used in creep/recovery mode was used for detection of the onset of elasticity in setting elastomers. The time for the materials to develop 5-20% elastic recovery corresponded with the time to reach a phase angle of 60 degrees in an oscillatory test.

PMID: 2398184 [PubMed - indexed for MEDLINE]

Skin grafting in severely contracted socket with the use of 'Compo'.

Indian J Ophthalmol. 1990 Apr-Jun;38(2):88-91

Authors: Betharia SM, Kanthamani , Prakash H, Kumar S

The results of split thickness autologous skin grafting along with the use of a dental impression material (Compo), a thermoplastic substance are presented in a series of 11 patients of acquired, severely contracted, anophthalmic sockets. Only the fornix fixation sutures and the central tarsorrhaphy were employed for the proper placement of graft without the use of retention devices. Artificial eyes were successfully fitted and retained subsequently after 6 weeks of grafting.

PMID: 2201626 [PubMed - indexed for MEDLINE]

Rheological properties of elastomers during setting.

J Dent Res. 1989 Aug;68(8):1218-22

Authors: McCabe JF, Carrick TE

A controlled stress rheometer has been used to monitor the changes in rheological properties occurring in five elastomeric impression materials during setting. The rheometer differs from conventional rotary viscometers in that the torque is the controlled variable, and the resulting deformation is measured. The use of such an instrument in oscillatory mode enables a range of rheological parameters--including viscosity, rigidity, and elasticity--to be monitored during setting. The polyvinylsiloxane impression materials develop elasticity at a rate that would not be apparent from measurements of viscosity or rigidity alone. This highlights the potential danger of basing the evaluation of clinically important properties, such as working time, on simple measurements of viscosity or rigidity.

PMID: 2632608 [PubMed - indexed for MEDLINE]

Dental impression materials: reactor response.

Adv Dent Res. 1988 Aug;2(1):65-70

Authors: Anusavice KJ

PMID: 3248140 [PubMed - indexed for MEDLINE]

Review of dental impression materials.

Adv Dent Res. 1988 Aug;2(1):51-64

Authors: Craig RG

PMID: 3073785 [PubMed - indexed for MEDLINE]

Tear strength of non-aqueous impression materials.

J Dent Res. 1984 Feb;63(2):155-7

Authors: Keck SC, Douglas WH

Examples from each of the four major groups of dental impression materials (polysulfides, polyethers, condensation polysiloxanes, and addition polysiloxanes) were subjected to a trouser-leg tear test. Tear energies were determined, and materials were ranked with respect to each other. Polysulfides displayed the highest tear energy, while condensation polysiloxanes were the lowest, with the addition polysiloxanes occupying an intermediate position.

PMID: 6582097 [PubMed - indexed for MEDLINE]

Acute tissue irritation of polysulfide rubber impression materials.

J Dent Res. 1983 May;62(5):548-51

Authors: Spranley TJ, Gettleman L, Zimmerman KL

The acute toxic reaction to 14 polysulfide rubber impression materials certified by the ADA was measured after injection into the oral mucosa of two baboons for 48 h, and the inflammatory response was evaluated quantitatively. Two materials were significantly more toxic than the others. Although light-bodied materials were less toxic and contained less lead, toxicity was not strongly related to lead content.

PMID: 6573369 [PubMed - indexed for MEDLINE]

Wetting effects of surface treatments on inlay wax-investment combinations.

J Dent Res. 1981 Nov;60(11):1858-60

Authors: Morrison JT, Duncanson MG, Shillingburg HT

Gypsum-bonded and phosphate-bonded investments were applied to wax surfaces which were untreated, treated by buffing with cotton moistened with a die lubricant containing organic solvent, or treatment with a wax pattern cleaner. Contact angles between the investment material and wax surfaces were measured and compared. The treatment of a wax pattern with a surface tension reducing agent significantly increases the degree of wetting by both gypsum- and phosphate-bonded investments.

PMID: 6945325 [PubMed - indexed for MEDLINE]

Temperature of elastomeric impression materials while setting in the mouth.

J Dent Res. 1980 Nov;59(11):1985-6

Authors: Sandrik JL, Sarna T

PMID: 6933184 [PubMed - indexed for MEDLINE]

Linear dimensional changes in elastic impression materials.

J Dent Res. 1980 Jul;59(7):1152-5

Authors: Marcinak CF, Young FA, Draughn RA, Flemming WR

Four classes of elastomeric impression materials (polysulfide, polyether, silicone, and agar-agar) were evaluated on the basis of linear dimensional stability as a function of time between taking and pouring an impression of mounted teeth. Four polysulfide materials produced dies which were larger than the teeth and generally increased in size with impression storage time. One silicone material produced dies slightly smaller than the teeth, and the dies from another silicone were dramatically smaller with increasing storage times. A polyether material produced slightly smaller dies for up to four hours' storage time, then increasingly larger dies up to 24 h. The dies from a reversible hydrocolloid were larger than the teeth for storage times up to 30 min, and then decreased rapidly at longer times.

PMID: 6929810 [PubMed - indexed for MEDLINE]

Apparent viscosities of setting elastomers.

J Dent Res. 1980 Jul;59(7):1149-51

Authors: Vermilyea SG, Huget EF, de Simon LB

The flow behavior of five elastomeric impression materials was determined by extrusion viscometry. Initial viscosity ranged from 400 to 5,100 poise at a shear rate of 2.2 reciprocal seconds. All of the elastomers showed initial non-Newtonian behavior and increased viscosity with time.

PMID: 6929809 [PubMed - indexed for MEDLINE]

Modifying the setting rate of an addition-type silicone impression material.

J Dent Res. 1979 Apr;58(4):1377-82

Authors: Stannard JG, Craig RG

Two methods for controlling the working time of an addition-type silicone impression material are presented. The progress of the polymerization reaction of this modified system was studied using viscosity and a new "compression set" technique. The physical properties are presented and compared to those typical of condensation silicones, and a method of clinical use is suggested.

PMID: 285107 [PubMed - indexed for MEDLINE]

Evaluating dimensional accuracy of stone models.

J Dent Res. 1979 Apr;58(4):1352-7

Authors: Hosoda H, Ohsawa M

An optical feeler measuring technique was introduced for evaluating the dimensional accuracy of indirect stone models. It presents the following advantages being able to measure the diameter of specimens in detail at various heights, indicating good reproducibility of the data; and hardly injuring the surface of the stone casts.

PMID: 285105 [PubMed - indexed for MEDLINE]

The effect of ultrasonic cleaning methods on rubber base impression materials.

J Dent Res. 1978 Sep-Oct;57(9-10):939

Authors: Lorton L, Phillips RW, Swartz ML

PMID: 281375 [PubMed - indexed for MEDLINE]