Conservative Restoration of Worn Mandibular Anterior Teeth Combining Gingival Repositioning and a Template Matricing Technique.

Conservative resin composite restoration of worn mandibular anterior teeth may offer an alternative option to full-coverage restorations for the patient. Assessment of the occlusal condition is critical because alterations in occlusal vertical dimension may not always be possible. By exposing additional coronal tooth structure, periodontal crown-lengthening procedures can serve to increase clinical crown height when adequate attached gingival tissue is present and supra-eruption has likely occurred. Fabrication of a custom template made from a diagnostic mock-up with proximal stainless steel matrices helps contribute to a predictable restorative result and improves chairside efficiency for the dental practice. By combining gingival crown lengthening, bonding of resin composite material, and selective occlusal adjustment; a short to medium-term, conservative option can be made available for the patient.

Shear bond strength of porcelain veneers rebonded to enamel.

In this laboratory research, shear bond strength (SBS) and mode of failure of veneers rebonded to enamel in shear compression were determined. Three groups (A, B, and C; n=10 each) of mounted molar teeth were finished flat using wet 600-grit silicon carbide paper, and 30 leucite-reinforced porcelain veneers (5.0 × 0.75 mm) were air abraded on the internal surface with 50 µm aluminum oxide, etched with 9.5% hydrofluoric acid, and silanated. The control group (A) veneer specimens were bonded to enamel after etching with 37% phosphoric acid using bonding resin and a dual cure resin composite cement. Groups B and C were prepared similarly to group A with the exception that a release agent was placed before the veneer was positioned on the prepared enamel surface and the resin cement was subsequently light activated. The debonded veneers from groups B and C were placed in a casting burnout oven and heated to 454°C/850°F for 10 minutes to completely carbonize the resin cement and stay below the glass transition temperature (Tg) of the leucite-reinforced porcelain. The recovered veneers were then prepared for bonding. The previously bonded enamel surfaces in group B were air abraded using 50 µm aluminum oxide followed by 37% phosphoric acid etching, while group C enamel specimens were acid etched only. All specimens were thermocycled between 5°C and 55°C for 2000 cycles using a 30-second dwell time and stored in 37°C deionized water for 2 weeks. SBS was determined at a crosshead speed of 1.0 mm/min. SBS results in MPa for the groups were (A) = 20.6±5.1, (B) = 18.1±5.5, and (C) = 17.2±6.1. One-way analysis of variance indicated that there were no significant interactions (α=0.05), and Tukey-Kramer post hoc comparisons (α=0.05) detected no significant pairwise differences. An adhesive mode of failure at the enamel interface was observed to occur more often in the experimental groups (B = 40%, C = 50%). Rebonding the veneers produced SBS values that were not significantly different from the control group. Also, no significant difference in SBS values were observed whether the debonded enamel surface was air abraded and acid etched or acid etched only.

Effects of abutment size and luting cement type on the uniaxial retention force of implant-supported crowns.

STATEMENT OF PROBLEM: The assumption that increasing the diameter of the abutment/crown components will provide greater resistance to crown loosening forces than standard-sized components has not been reported either with clinical trials or in the laboratory. PURPOSE: This study attempted to determine what effect abutment dimension and type of luting agent have on the retention of the prosthetic crown. METHODS AND MATERIAL: Test specimens consisted of standard, wide, and "experimental" CeraOne titanium abutments and matching CeraOne gold cylinders cemented with a zinc phosphate permanent or a zinc oxide eugenol provisional cement. The mean uniaxial force (Newtons) and the load (MPa) required to dislodge the cylinder from the abutment was determined. Statistical analysis of the sample data was performed using a 2-way analysis of variance test (alpha=.05). RESULTS: Mean uniaxial resistance force (Newtons) was significantly greater for zinc phosphate cement than for zinc oxide cement (P <. 001). Abutment size was a significant factor when permanent luting cement is used (P <.001). Retention strength per unit area (MPa) of the wide abutments was lower than the standard size and "experimental" abutments. CONCLUSION: Permanent luting cement produced uniaxial retention forces approximately 3 times greater than provisional cement. The increase in surface area provided by a wide abutment did not result in an improvement in retention strength over the standard abutment.

Pharmacokinetics of bisphenol A released from a dental sealant.

BACKGROUND: Limited information is available regarding potentially estrogenic bisphenol A, or BPA, released from dental sealants. This study determined the rate- and time-course of BPA released from a dental sealant (Delton Opaque Light-cure Pit and Fissure Sealant, Preventive Care/Dentsply) when applied at a dosage of 8 milligrams (one tooth) or 32 mg (8 mg on each of four teeth) to 40 healthy adults. METHODS: The authors recruited 40 healthy subjects (18 men and 22 women, 20-55 years of age) who did not have histories of pit and fissure sealant placement or composite resin restorations. The authors collected saliva (30 milliliters) and blood (7 mL) specimens from all subjects immediately before sealant placement (baseline) and at one hour, three hours, one day, three days and five days after sealant placement. They used high-pressure liquid chromatography to determine BPA (detection sensitivity 5 parts per billion, or ppb) in all specimens. RESULTS: The authors detected BPA in some saliva specimens (5.8-105.6 ppb) collected at one hour and three hours. The BPA, however, was not detectable beyond three hours or in any of the serum specimens. For the one- and three-hour saliva samples, the BPA concentration in the high-dose (32 mg) group was significantly greater than in the low-dose (8 mg) group (P < .05, Wilcoxon signed rank test). In the high-dose group, there was a significant decrease in saliva BPA concentrations from one hour to three hours (P < .01, Wilcoxon signed rank test). CONCLUSION: This study showed that BPA released orally from a dental sealant may not be absorbed or may be present in nondetectable amounts in systemic circulation. The concern about potential estrogenicity of sealant may be unfounded.

Effect of dentin primer on the shear bond strength between composite resin and enamel.

The purpose of this investigation was to determine the effect of dentin primers from Scotchbond Multi-Purpose, ProBond, All-Bond 2, and Syntac on the shear bond strength of composite resin to etched enamel. Two groups of extracted human molar teeth with flattened enamel surfaces (n = 12) were randomly assigned to each enamel/dentin bonding system. Following manufacturers' instructions enamel surfaces were etched, rinsed, and dried. Composite bonding procedures were conducted similarly in both groups for each enamel/dentin bonding system, except that in one of the two groups, dentin primer was applied prior to adhesive resin and composite placement. Samples were thermocycled and tested in shear until failure. Fracture analysis was performed on enamel surfaces with both light and scanning electron microscopy. Shear bond values (Mean +/- SD, MPa) were: Scotchbond Multi-Purpose unprimed 22.4 +/- 3.2, primed 17.9 +/- 5.9; ProBond unprimed 19.4 +/- 6.2, primed 18.3 +/- 3.3; All-Bond 2 unprimed 19.0 +/- 3.6, primed 17.3 +/- 3.0; and Syntac unprimed 26.2 +/- 9.0, primed 22.0 +/- 5.4. The only significant difference found between primed and unprimed groups was with Scotchbond Multi-Purpose, though there was a trend for primer application to decrease enamel bond strengths. Fracture surface analysis revealed that most failures were cohesive within the composite resin. These data suggest that the effect of primer on bonded composite resin to etched enamel is material specific.

Surface roughness of light-activated glass-ionomer cement restorative materials after finishing.

The purpose of this study was to compare the effect of various finishing sequences on the surface roughness of four new light-activated (LAGIC) restorative materials. Restorative materials included a polyacid-modified composite resin (Variglass VLC) and three resin-modified glass-ionomer cements (Vitremer, Photac-fil, and Fuji II LC). Thirty specimens of each material were prepared in Macor dies and randomly divided into six finishing sequence groups (n = 5): (1) Mylar strip (control), (2) carbide bur/Sof-Lex XT disks, (3) ET finishing diamonds, (4) carbide bur/Enhance polishing system, (5) carbide bur/Politip rubber finishers, and (6) carbide bur alone. Average surface roughness (Ra) in micrometers was measured with a Mitutoyo Surftest 401 Surface Roughness Tester and the data compared using ANOVA, Student-Newman-Keuls Multiple Comparison tests, and Dunnett's test at P < or = 0.05. Surface topography was also assessed using the scanning electron microscope (SEM) on epoxy replicas from samples of each group. The Mylar strip produced the smoothest surface and finishing sequences; (2) and (3) were significantly smoother than (4), (5), and (6). There were no significant differences between restorative materials when all finishing sequences were combined. SEM analysis was consistent with the profilometer results. Materials with higher (Ra) values appeared to have rougher surfaces. Rubber abrasives and polishing pastes seem to preferentially remove the polysalt and resin matrix of these materials.

Microleakage of dentin-amalgam bonding agents.

PURPOSE: To evaluate in vitro the microleakage of various dentin bond/resin liner systems when used with both a spherical and an admixture alloy. MATERIALS AND METHODS: Class V cavity preparations were prepared on 60 noncarious extracted human molar teeth with one margin in enamel and another in dentin and restored with either Dispersalloy or Tytin alloy. Treatment groups utilizing either no liner, Copalite varnish, Amalgambond Plus/HPA, Tenure with Panavia EX Dental Adhesive, Syntac with Dual Cem, and All-Bond 2 with Liner F were tested. Samples were thermocycled, stained, and sectioned to evaluate microleakage. RESULTS: A significant reduction in microleakage at the enamel and dentin margins was found in all dentin bond system/resin liner groups when compared to unlined and Copalite-lined alloys. There were no significant differences in total microleakage scores between the alloy types. Statistically significant differences in microleakage were detected between some systems. The Tenure with Panavia EX treatment group exhibited a significantly lower total microleakage when used with Tytin. The Syntac/Dual Cem treatment groups exhibited a significantly higher total microleakage when used with Dispersalloy.

Direct esthetic restoration of anterior root canal-treated teeth.

The esthetic restoration of anterior root canal-treated teeth with significant loss of tooth structure is a challenging clinical situation. For younger patients or for patients requiring interim treatment plans, restoring badly broken-down anterior teeth with composite resin provides an expedient and esthetic solution. Current visible-light-activated composite resin materials require an incremental build-up to ensure adequate depth of cure. With the use of custom-contoured, stabilized, thin crown forms and strategically placed vent holes, the clinician can efficiently provide cost-effective direct composite resin restorations that meet the patients' esthetic needs.

Microleakage of a dental amalgam alloy bonding agent.

Amalgambond (a 4-META derivative resin bond agent) was evaluated for its effectiveness in reducing microleakage compared to copal varnish and no lining agent in class 5 amalgam preparations restored with either an admix alloy (Dispersalloy) or a spherical alloy (Tytin). Teeth were thermocycled between 5 and 55 degrees C with two 4-META/amalgam groups additionally aged in 37 degrees C water for 30 days prior to thermocycling. Nonaged, 4-META/amalgam restorations showed significantly less microleakage (P < 0.05) at enamel and dentin margins compared to copal varnish or nonlined restorations. Within the 4-META groups, the 4-META/Dispersalloy restorations had significantly less microleakage than the 4-META/Tytin restorations at enamel margins. Microleakage in the aged 4-META/amalgam restorations was significantly greater at both the enamel and dentin margins than in the analogous nonaged groups. SEM evaluation of the 4-META lined restorations found internal cavity surfaces of the preparations to be sealed by the resin liner with separations and apparent microleakage occurring at the 4-META/amalgam interface.