Aldridge D. Wilder

Examining Tooth Flexure Effects on Cervical Restorations: A Two-Year Clinical Study

This study evaluated the clinical performance of dentinal adhesives in seven various material/technique combinations. No statistically significant differences were observed among the restorative combinations, or among technique variables after two years in terms of retention, sensitivity or USPHS categories. However, other factors related to tooth flexure--such as occlusal stress, patient age, restorative material and restoration location--showed statistically significant associations with retention failures. These results support a tooth flexural theory of restoration retention.

Clinical Evaluation of an All-in-one Adhesive in Non-Carious Cervical Lesions with Different Degrees of Dentin Sclerosis

This randomized clinical trial compared the performance of an all-in-one adhesive (iBond) applied in sclerotic and non-sclerotic non-carious cervical lesions with that of a three-step etch-prime-bond adhesive (Gluma Solid Bond, SB). One-hundred and five lesions were randomly assigned to four groups according to adhesive, sclerosis scale and technique: 1) SB applied to lesions with sclerosis scale 1 and 2 (n=26); 2) iBond applied to lesions with sclerosis scale 1 and 2 (n=28); 3) iBond applied to lesions with sclerosis scale 3 and 4 (n=25) and 4) iBond applied with prior acid-etching to lesions with sclerosis scale 3 and 4 (n=26). A microfilled composite (Durafill VS) was used as the restorative material. The restorations were evaluated for retention, color match, marginal adaptation, anatomic form, cavosurface margin discoloration, secondary caries, pre- and post-operative sensitivity, surface texture and fracture at insertion (baseline), 6, 18 months and at 3 years using modified USPHS evaluation criteria (Alfa=excellent; Bravo=clinically acceptable; Charlie=clinically unacceptable). There was a high percentage of Bravo scores for marginal adaptation (4%-32%) and marginal discoloration (18%-60%) in Groups 2, 3 and 4, but all groups had <5% Charlie scores at 6 months and <10% Charlie scores at 18 months for retention and marginal discoloration, respectively. However, it should be noted that 13% of the restorations in Group 4 were not retained at three years.

Five-year study of two lightcured posterior composite resins

Abstract Two visible light-cured composite resins, Ful-Fil and X-55, were used to restore 136 Class I and Class II cavity preparations in adult teeth. After 5 years the ratings for color matching, interfacial staining, secondary caries, and marginal adaptation remained good, using USPHS criteria (ranging from 75% to 100% Alfa). The average surface loss due to occlusal wear was 158 and 169 micrometers for Ful-Fil and X-55, respectively. Significant differences in occlusal wear were noted depending on tooth and restoration type. These results indicate that both composite resins meet the current ADA Council on Dental Materials specifications for full acceptance in adult posterior teeth.

Three-year clinical study of UV-cured composite resins in posterior teeth

Four proprietary composite resins cured with ultraviolet light were inserted into Class I and II cavity preparations. The restorations were evaluated over a 3-year period for color match, interfacial staining, secondary caries, loss of anatomic form, marginal adaptation, and surface texture. The percent of restorations exhibiting no generalized loss of anatomic form ranged from 47% to 93%.

Comparison of direct and indirect methods for analyzing wear of posterior composite restorations

The vast majority of recent clinical research involving wear analyses of posterior composite resin restorations have used either the direct evaluation method (USPHS) or the indirect cast comparison (Leinfelder) method. However, there has never been any established correlation of the two wear scales. The objective of this study was to determine the amount of wear for the USPHS alfa-bravo transition on the basis of cast comparison data. Clinical wear data were collected over five years by both the direct method and the indirect method. Three materials were used involving a total of 221 restorations in 61 patients. Each restoration was evaluated at baseline, six months, one, two, three, and five years by each method. Then, for those restorations which underwent a transition from an alfa to a bravo clinical rating, the absolute wear at the transition was determined by averaging the indirect ratings just before and just after the transition. The mean wear corresponding to the alfa-bravo transition was 192 +/- 60 microns. Because of the large width of the alfa category up to the alfa-bravo transition, extensive early changes and high initial wear rates cannot be detected by the USPHS system.

Confirmation of Leinfelder clinical wear standards

OBJECTIVES Accuracy of composite wear studies based on Leinfelder standards has been disputed. There are differences with other well-calibrated systems such as the M-L and Vivadent wear standards. The objective of this study was to reevaluate the margin height at key regions along the restoration margins for each of the 6 Leinfelder standards using laser profiling techniques. METHODS The Leinfelder standards were profiled in parallel paths 100 microns apart and measured in x-y-z position every 20 microns along those paths using a laser profilometer. RESULTS Rounding of cavosurface enamel margins from intraoral wear greatly increased the uncertainty of the true enamel margin location and step height measurements, precluding unequivocal measurements for standards #2 and #3. Values for other standards for the original report, newly measured means and standard errors, and measured ranges were: #4 (322 microns, 333 +/- 34 microns, 171-507 microns), #5 (382 microns, 459 +/- 44 microns, 202-649 microns), and #6 (493 microns, 584 +/- 91 microns, 315-1022 microns). There were no statistically significant differences (p < or = 0.10) between these and original values. Large standard errors may have obscured small differences that may exist. The Leinfelder cast conversion scale seems to be the correct relative magnitude. SIGNIFICANCE Differences between Leinfelder casts and other standards may be due to differences in shadow production. Clinical wear may be systematically underestimated by other cast evaluation methods that have well-defined margins. This emphasizes the need for standard casts with margin morphology similar to the clinical casts being evaluated for wear.

Two-year clinical study of composite resins in posterior teeth

Abstract Lack of resistance to abrasion and loss of anatomic form have characteristically been attendant problems of first generation composite resins placed in posterior teeth. Variations in method of polymerization, filler content, particle size, and particle composition have been attempted to improve clinical characteristics. The purpose of this study was to evaluate the clinical performance of 5 different composite resins placed in Class I and Class II preparations. All restorations were evaluated directly using USPHS criteria. Indirect evaluations of the restorations on diestone casts were made to categorize quantitatively the amount of occlusal wear. No statistically significant differences among the materials regarding wear were observed when using USPHS criteria. However, statistically significant differences in the results detected by indirect evaluation suggest that loss of anatomic form may be related to the size and composition of the filler particles in the resin restorative materials.

Three-year clinical evaluation of a self-cured posterior composite resin.

A study was conducted to determine whether the wear resistance of a posterior composite could be improved by maximizing filler particle-to-particle contacts. This was expected to reduce stress concentrations on the resin matrix and thus reduce occlusal wear. A self-curing quartz-filled composite with this design, P-10, was used to restore 90 Class I and II cavity preparations in adult teeth. Restorations were recalled after baseline at six months, one year, two years, and three years to measure wear by direct and indirect evaluation methods. There was no apparent advantage for this material compared with other previously evaluated posterior composites. The average cumulative wear for P-10 after three years was 145 microns. In addition, the restorations were evaluated for color-matching, interfacial staining, secondary caries, marginal adaptation, surface texture, and postoperative sensitivity. This material was not significantly different in those ways from other posterior composite products except in terms of more rapid color change, because it is self-cured.

Effects of duration of whitening strip treatment on tooth color: A randomized, placebo-controlled clinical trial

OBJECTIVES A randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate efficacy and safety of 6% hydrogen peroxide whitening strip used twice daily over an extended, 6-week period. METHODS After informed consent, 40 eligible adults were randomly assigned to 6% hydrogen peroxide whitening strips (Crest Whitestrips, The Procter & Gamble Company, USA) or placebo strips without peroxide. Treatment was twice daily for 30min, and response was evaluated biweekly after initial (Week 2) and extended (Weeks 4 and 6) use. Tooth color was measured under standardized lighting conditions using digital image analysis, and safety was assessed from clinical examination and interview. Whitening was measured using data derived from digital images taken at baseline compared to post-treatment, with outcomes reported using the CIELAB color notation system. Analysis of variance and covariance were used to assess initial response, and repeated measures regression analysis was used to model color change during sustained use. RESULTS Forty subjects (25-58 years old) started the study. At baseline, L* ranged from 68.0 to 76.8, a* ranged from 8.0 to 11.8, and b* ranged from 16.4 to 23.1. Groups differed significantly (p<0.001) on all color parameters at Week 2 and thereafter, favoring the 6% hydrogen peroxide strips. Week 2 adjusted means+/-SE were -2.1+/-0.2 for Deltab* and 1.9+/-0.2 for DeltaL* for the peroxide group compared to -0.3+/-0.2 for Deltab* and 0.4+/-0.2 for the placebo group. With sustained use (Weeks 2-6), the slope for the peroxide strip was estimated as -0.3 for Deltab* and +0.2 for DeltaL* per week, with both slopes differing significantly from zero (p<0.0001), while slopes for the placebo strip were not significant (p=0.22) and nearly zero. Treatment was generally well tolerated, with adverse events confined to symptoms only. CONCLUSIONS Twice-daily use of 6% hydrogen peroxide whitening strips resulted in teeth becoming lighter and less yellow versus baseline and placebo during initial 2-week use, with no evidence of placebo response during sustained (Weeks 2-6) use.

Wear of a dental composite in an artificial oral environment: A clinical correlation.

The study objective was to correlate wear between an in vitro method for simulating wear and in vivo wear of a posterior dental composite. Ten subjects (12 restorations) were selected from a five-year clinical study (University of North Carolina, School of Dentistry) that assessed wear of SureFil composite (Caulk, Dentsply). Subject casts were digitized and changes in volume and mean depth with time were calculated from the 3D digital models for contact and contact-free wear. SureFil composite disks were mounted in the University of Minnesotas Artificial Oral Environment, opposed by natural enamel, subjected to mandibular-like movements for 150 K, 300 K, 600 K, 1.2 M, and 1.5 M cycles, and loaded with peak forces of 13 N (n = 7) or 30 N (n = 3). Wear rates were calculated as the slope of the linear regressions fitting the wear data. Data were analyzed using one-way ANOVAs and post hoc t-tests where appropriate (p = 0.05). Clinical restorations included contact wear on seven restorations and contact-free wear on all restorations. Contact-free wear was less than contact wear (p < 0.01). SureFil clinical wear rates were 0.012 mm/year (mean depth) and 0.023 mm(3)/year (volume). Clinical restorations expanded slightly during the first year. Using a conversion rate of one year equals 3 × 10(5) cycles, there were no significant differences between the clinical and simulated data except depths at Year 5 and 13 N volume at Year 4. The 30 N simulation reproduced the clinical data if contact-free wear was taken into account. Good agreement between simulated and clinical wear implies that in vitro simulation can screen new composite formulations.