Technique on restoring cervical lesions.

This paper describes a technique of placing a semi-rigid cervical matrix slightly past the cervical border of a lesion that extends below (apical to) the gingival crest and inserting the glass ionomer cement through an opening cut in the matrix above the soft tissue level.

Degradation of bleaching gels in vivo as a function of tray design and carbamide peroxide concentration.

This study determined the degradation of nine bleaching agents with different concentrations after two hours in vivo following the manufacturers' recommendations. The nine carbamide peroxide products are 10%, 15% and 20% Opalescence, 10%, 15% and 22% Rembrandt and 10%, 16% and 22% Nite White Excel 2. Each subject wore the tray with the bleaching agent for two hours on three separate occasions. The amount of remaining carbamide peroxide was determined after each use. Evaluation of remaining amount of carbamide peroxide was calculated by the US Pharmacopeia method. The study showed that the total carbamide peroxide percent recovered was significantly higher for Opalescence products (47% to 54%) compared to Nite White (22% to 25%) and Rembrandt bleaching gels (15% to 16%). It concluded that this difference was mostly due to the use of facial reservoirs with Opalescence products, and also that whitening gel in trays with reservoirs and trays without reservoirs degraded at the same rate.

A clinical evaluation of a bleaching agent used with and without reservoirs.

This in vivo study evaluated the variation of tray fabrication (trays constructed with or without reservoirs) on the degree of color change of teeth and sensitivities associated with using a 15% carbamide peroxide bleaching agent for two hours once daily for 14 days. Patients returned in one, two, three, six and 12 weeks. Color changes were evaluated by subjective shade matching, comparing clinical photographs and through measurements obtained using a color-measuring device. Subjects were asked to keep a daily record of any tooth and gingival sensitivity on the right and left side of their maxillary dental arch for three weeks. Colorimeter data showed that teeth lightened with agent with reservoirs were significantly lighter than teeth lightened with the same agent without reservoirs. However, the amount of lightening was below the threshold of visual differentiation. Shade guide and slide photography data showed no significant differences between teeth lightened with agent with reservoirs compared to teeth lightened with the same agent without reservoirs. In addition, no significant differences in tooth and gingival sensitivity were found between the tray side with reservoirs and those without reservoirs.

Microleakage of posterior packable resin composites with and without flowable liners.

The use of flowable composites as liners in Class II packable composites has been suggested by some manufacturers. However, the contributions of this technique are unproven. This study evaluated marginal microleakage in Class II packable composite restorations with and without the use of a flowable composite liner. A conventional microhybrid composite was used as a control. Microleakage at occlusal and gingival margins of Class II cavities was evaluated using 45Ca and autoradiographs. Fifty non-carious, restoration-free human molar teeth were used. Separate mesio-occlusal and disto-occlusal Class II cavity preparations were made in each tooth. Gingival margins of all cavities were placed 1 mm apical to the cementoenamel junction (CEJ). Four Packable composites (Alert, Surefil, Pyramid and Solitaire) and one conventional microhybrid composite (Renew) with their respective manufacturer's bonding agents were used to restore the cavities. One side of each tooth was restored with composite alone, while the other side was restored with the composite lined with that manufacturer's flowable liner. The restored teeth were thermally stressed and 45Ca was used to evaluate microleakage. Two independent evaluators scored leakage based on the autoradiographs. The results showed flowable composites helped reduce microleakage at gingival margins of Class II restorations (p < 0.05). Gingival margins had higher microleakage than occlusal margins (p < 0.05). Without flowable liners, three packable composites (Alert, Pyramid and Surefil) showed higher leakage (p < 0.05) than the microhybrid control. Only Solitaire packable composite without liner showed no significant difference in microleakage to the control (p > 0.05). Although the flowable liners help reduce microleakage, Alert and Pyramid packable composites with liners still showed higher leakage than the control (p < 0.05). Surefil and Solitaire packable composites with flowable liners showed no significant difference in microleakage (p > 0.05) to the control.

A clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime use.

BACKGROUND: Vital tooth bleaching for esthetic reasons has gained in popularity during the last few years. However, few studies have investigated the efficacy of daytime bleaching products. The purpose of this double-blind in vivo study was to evaluate the efficacy of 20 percent carbamide peroxide, or CP, and 7.5 percent hydrogen peroxide, or HP, during daytime use. The degree of color change, any color relapse, and tooth or gingival sensitivity were evaluated. METHODS: Twenty-four patients participated in this study. The bleaching gels were randomly applied to the right and left maxillary anterior teeth. Patients were shown how to place the two bleaching agents in a custom tray for one hour, twice a day for two weeks. Patients returned in one, two, three, six and 12 weeks for color evaluation with the colorimeter and shade guides as well as to have color slide photographs taken. The authors evaluated sensitivity by asking the patients to record daily for 21 days any tooth or gingival sensitivity they experienced. RESULTS: Use of the 20 percent CP resulted in significantly more lightness than the 7.5 percent HP during the first 14 days of the study, but at the end of the study, there was no significant difference between products with regard to tooth lightness. In addition, the authors found no statistically significant difference between products with regard to gingival or tooth sensitivity. CONCLUSIONS: Both CP and HP are effective at-home bleaching agents when daytime bleaching is preferred. CLINICAL IMPLICATIONS: Dentists who choose to use daytime bleaching can select either CP or HP.

Clinical evaluation of bleaching agents of different concentrations.

OBJECTIVE: The purpose of this study was to evaluate the degree of color change, any rebound effect, and sensitivities associated with using 2 different concentrations of carbamide peroxide in vivo. METHOD AND MATERIALS: Twenty-five subjects used 10% and 15% agents in trays for 14 days on different sides of their maxillary arches. Subjects returned in 3 days and at 1, 2, 3, and 6 weeks for evaluation of color change and rebound effect. Shade matching, photographic means, and a colorimeter were used for evaluation. Subjects self-reported gingival and tooth sensitivity on a scale of 1 (no sensitivity) to 5 (severe sensitivity). RESULTS: After 2 weeks, delta L*, delta a*, delta b*, delta E* and delta shade guide rank means for the 10% whitening agent were 6.50, -1.37, -4.63, 8.79, and -15.40, respectively; for the 15% agent, they were 8.72, -1.63, -5.90, 11.03, and -16.59, respectively. After 6 weeks, delta L*, delta a*, delta b*, delta E*, and delta shade guide rank means for the 10% whitening agent were 3.04, -0.99, -3.19, 5.13, and -13.13, respectively; for the 15% agent, they were 3.48, -1.01, -3.60, 5.58, and -13.65, respectively. Means for gingival sensitivity were 1.18 and 1.21 for the 10% and 15% agents, respectively; means for tooth sensitivity were 1.21 and 1.26 for the 10% and 15% agents, respectively. CONCLUSION: All 3 methods of evaluation revealed a significant difference in the tooth lightness achieved by 10% and 15% products at 2 weeks but no significant difference at 6 weeks. No statistically significant difference was found in gingival or tooth sensitivity.

Evaluation of an illuminated mirror.

The viewing of oral structures with an adequate level of illumination is necessary to make accurate diagnoses of normalities and abnormalities in the oral cavity. The purpose of this study is to determine if a device with an illuminated mirror is heat sterilizable, easy to use, and compares in illumination potential to a traditional overhead dental operating light. We sterilized the Denlite in both chemical vapor and autoclave units (including a group that was cleaned ultrasonically prior to autoclave), testing the illuminance level every 10 cycles, for 100 cycles. We installed devices in the Graduate Operative Dentistry Clinic and requested those operators assigned to the units to rate the devices. Their acceptance rate was high in visibility, ease of use, acceptable temperature of handle, and lack of problems with the device. The device had an illuminance level of 14,200 lux, which is just below the maximum level of illuminance required by the American Dental Association's Specification on Dental Operating Lights.

A clinical study of the effect of pellicle on the degradation of 10% carbamide peroxide within the first hour.

OBJECTIVE: The purpose of this study was to determine the degradation of 10% carbamide peroxide within the first hour of use and the effect of pellicle on the degradation of carbamide peroxide in vivo. METHOD AND MATERIALS: Fifteen subjects were assigned to wear nightguard trays filled with bleaching gel for 0.5, 2.5, 5.0, 10.0, 20.0, 40.0, and 60.0 minutes under 2 conditions: (1) subjects did not receive a prophylaxis before each bleaching treatment (pellicle was assumed to be present on the tooth surface); and (2) subjects received prophylaxis to remove pellicle from the tooth surface. At each evaluation time, 3 types of sample were collected: (1) a "grab sample," a sample of gel taken with a spatula from the reservoir of the tray on the maxillary right central incisor; (2) the remaining gel from the tray; and (3) the remaining gel scraped from the teeth. The collected gel samples were analyzed for the amount of peroxide using the United States Pharmacopeia-accepted method. Subjects were asked not to swallow the saliva during treatment but to expectorate into a beaker. The collected saliva was analyzed to determine the amount of peroxide. This sample represented the approximate amount of peroxide that subject would ingest during treatment. RESULTS: Pellicle did not affect the degradation of carbamide peroxide for the teeth or grab samples. The degradation of carbamide peroxide was exponential, except during the first 5 minutes, when the degradation rate was much higher. The saliva collected from subjects during use of the bleaching tray revealed an average of 2.1 mg of carbamide peroxide for 1 hour of bleaching treatment. CONCLUSION: The degradation rate is not affected by the removal of the pellicle.

The efficacy and safety of a 10% carbamide peroxide bleaching gel.

OBJECTIVE: A 6-month, double-blind study was undertaken to assess the efficacy and safety of a 10% carbamide peroxide gel designed for at-home tooth bleaching. METHOD AND MATERIALS: Sixty patients were randomized into two equal subgroups balanced by age, gender, and oral health status. Shade guide measurements, color transparency photographs, and colorimeter readings were taken and evaluated at baseline and 1, 2, 3, 6, 12, and 24 weeks. The active phase of treatment lasted 14 days. RESULTS: At 22 weeks postbleaching (week 24 of the study), patients receiving the active agent had a 14.1 rank order difference in the shade guide from baseline, and 66% had a clinically observable color change as determined by photographic assessment. They also had a measurable, statistically significant color change from baseline to 6 months of delta E* = 5.0. The tooth color of maxillary incisors stabilized at week 6 and maxillary canines at week 12. The mean color change lost from weeks 2 to 24 was 45% (in delta E*). Transient tissue and tooth sensitivity, noted in some patients, resolved after treatment was completed. CONCLUSION: The product tested is an effective and safe tooth-whitening agent.

In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents.

STATEMENT OF PROBLEM: Anecdotal reports based on clinical observation have recently linked resin-modified glass ionomer luting agents with postcementation fracture of all-ceramic crowns. PURPOSE: This study evaluated the fracture incidence of In-Ceram and VitaDur Alpha porcelain jacket all-ceramic crowns cemented with 5 luting agents (Fuji I, Fuji Plus, Vitremer, Advance, and Panavia 21) during 2 months storage in 0.8% NaCl solution. MATERIAL AND METHODS: Fifty human maxillary premolar teeth were prepared for each ceramic system and divided into 5 subgroups of 10 teeth to be cemented with 5 luting cements. Specimens were observed for fracture lines and crack initiation at storage times up to 2 months. Incidence of fracture was analyzed with Fisher's Exact test. Specimens that did not fracture during storage were loaded in compression to failure. Failure loads were analyzed by analysis of variance and multiple pairwise comparisons. RESULTS: Only all-ceramic crowns cemented with Advance cement fractured during the 2-month observation period, and porcelain jacket crowns were found to fracture earlier and more frequently than In-Ceram crowns. Cracks initiated at the crown margin, and multiple crack lines were found as the time of storage increased. In-Ceram crowns were significantly stronger (140 +/- 21.5 kg) than porcelain jacket crowns (98.6 +/- 17.8 kg) at P <.05. For In-Ceram crowns, cement type did not influence failure load while for porcelain jacket crowns, Fuji I (110.5 kg) was significantly higher than Vitremer (86.6 kg) at P <.05. CONCLUSIONS: For the cements studied, only crowns cemented with Advance cement demonstrated fracture during 2-month storage. Results for the true resin-modified glass ionomer cements do not support anecdotal reports of fracture of all-ceramic crowns cemented with these materials.

Microleakage evaluation of bonded amalgam restorations: confocal microscopy versus radioisotope.

The purpose of this study was to compare the degree and pathway of microleakage in bonded amalgam restorations utilizing fluorescent dyes with scanning laser confocal microscopy and 45Ca radioisotope with autoradiographs. Mesial slot preparations with enamel cervical margins and distal preparations with dentin margins were prepared in extracted human molars. Four liners, Copalite (control) All-Bond 2/Resinomer, Amalcoden, and Panavia 21, were used. Teeth were restored with Dispersalloy or Tytin. After thermocycling, 7 days' storage, and staining, the degree of microleakage was measured on an ordinal scale. Dental adhesive liners minimized microleakage; the ranking was, from most to least effective, All-Bond 2, Panavia 21, and Amalcoden. The control exhibited the greatest microleakage. Microleakage occurred most frequently at the liner-tooth interface. No significant difference was observed between amalgams. The high correlation between the results of the fluorescent and radioisotope studies indicated that these two microleakage tests can be directly compared.

Digestibility, apparent mineral absorption, and voluntary intake by horses fed alfalfa, tall fescue, and caucasian bluestem.

Alfalfa (Medicago sativa L.), low-endophyte (< 5%) tall fescue (Festuca arundinacea Schreb.), and caucasian bluestem (Bothriochloa caucasica [Trin.] C.E. Hubbard) were fed as chopped hay to six Arabian geldings (BW 441 kg; SE 2) in intake and digestibility experiments to determine nutritional value for horses at maintenance. Each experimental design was a replicated Latin square. Alfalfa was higher in DM and CP digestibility, IVDMD, apparent absorption of Ca, K, and S, and voluntary intake than the grasses (P < .05). Caucasian bluestem was higher in Zn but was lower in CP, TNC, Mg, P, K, S, and Cu concentrations than tall fescue. Crude protein digestibility and apparent absorption of Mg, K, and S were higher (P < .05) for tall fescue than for caucasian bluestem. Geldings fed alfalfa for ad libitum intake had higher serum concentrations of vitamin A, blood urea nitrogen, P, S, and Cu than geldings fed grass hays. Serum Zn was higher (P < .05), whole blood Se tended to be higher (P < .06), and BUN was lower (P < .05) in geldings fed caucasian bluestem than in those fed tall fescue. All forages met requirements for CP, Ca, Mg, K, and Fe when fed for ad libitum intake but were deficient in Cu for horses at maintenance. Caucasian bluestem was borderline in CP and was deficient in P but was the only forage that met the Zn requirement for the horses. Based on these results, caucasian bluestem could be a useful hay for horses but may require supplementation of CP and P.

The effect of air abrasion on shear bond strength to dentin with dental adhesives.

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).

Using a resin-modified glass ionomer as an occlusal sealant: a one-year clinical study.

The authors compared the retention and clinical performance of a resin-modified glass ionomer, or RMGI, restorative and a light-cured resin sealant. The first permanent molars on one side of the dental arch in 50 children were sealed with an RMGI, and the same teeth on the other side were sealed with a resin sealant. At baseline, six months after placement and one year after placement, examiners documented sealant retention, secondary caries, marginal discrepancy and marginal staining. In general, the RMGI appeared to wear markedly. At one year, the retention of the RMGI was significantly less than the resin, but the RMGI had significantly fewer marginal discrepancies. There were no significant differences in caries development or marginal discoloration.

Influence of bonded amalgam restorations on the fracture strength of teeth.

This study evaluated the effect of bonded amalgam on the fracture strength of teeth using five adhesive systems: Panavia 21, Amalgambond Plus, Imperva Dual Bond, All-Bond 2 Primer/Bonding Resin, and All-Bond 2 Primer/Liner F. Intact teeth and amalgam lined with Copalite were used as control groups. Large MOD preparations were made in 20 extracted maxillary premolars for each group. The teeth were restored with Tytin. All groups were stored in water at 37 degrees C for 15 days and thermocycled 2500 times, over 8-48 degrees C. The specimens were preloaded five times in compression to 10 kg using a 5 mm-in-diameter, cylindrical steel indenter that contacted the teeth only on the cuspal inclines. Then the teeth were loaded to failure at 5.0 mm/min. The failure mode was recorded (amalgam failure, cusp fracture, or failure at the tooth/amalgam interface). The mean fracture strengths were analyzed using ANOVA and Newman-Keuls multiple comparisons. The Imperva Dual Bond group showed the highest mean forces followed by All-Bond 2 Primer/Bonding Resin. The All-Bond 2 Primer/Liner F and Amalgambond Plus groups demonstrated lower means and were not significantly different from the Copalite group. The Panavia 21 group was in between these two groups and was not statistically different from either group. The mean strength of intact teeth was the highest, but its very large coefficient of variation (60%) prevented effective use of these data for statistical comparison. Analysis of the mode of fracture showed that Panavia 21, All-Bond 2 Primer/Bonding Resin, and Amalgambond Plus failed cohesively in the amalgam in 35%, 25%, and 15% of the specimens respectively. This fracture type is a good indication of effective bonding between tooth and amalgam. The most common type of fracture for all the restored groups was the one that occurred at the tooth/restoration interface. This would suggest that current bonding procedures could be improved.