Evaluation of bovine and human teeth exposed to thermocycling for microleakage under bonded metal brackets.

INTRODUCTION: Bovine teeth are commonly used as substitutes for human teeth in scientific investigations. The present study was performed in vitro with the objective of comparing bovine and human enamel subjected to thermocycling for microleakage beneath metal brackets. MATERIALS AND METHODS: A total of 50 bovine and human teeth (25 per group) void of defects or carious decay were extracted and stored in chloramine B (0.5%). A light-curing adhesive (Transbond™ XT) was used as instructed by the manufacturer (3M Unitek, Monrovia, CA, USA) to bond a metal bracket (discovery®; Dentaurum, Ispringen, Germany) to the surface of each tooth following 30 s of enamel etching (phosphoric acid 35%). After 24 h of dye penetration in methylene blue (0.5%), the cervical and incisal bracket surfaces were analyzed by light microscopy for excess bonding material, dye penetration, and microleakage at the bracket-adhesive and adhesive-enamel interfaces. Staining and evaluation was repeated after thermocycling (5000 cycles at 5/55 °C). RESULTS: Before thermocycling, the number of human teeth showing marginal gaps was one-third the number of bovine teeth (p<0.001). After thermocycling, the distribution of gaps was similar (p=0.180). The adhesive-enamel interface was most frequently affected (on 74% of human and 64% of bovine teeth). No dye penetration in either group after examining a horizontal slice through the bracket basis was observed. CONCLUSION: Immediately after bonding, less microleakage was observed around the base of metal brackets on human than bovine teeth. These marginal gaps were, however, superficial in both groups, none of them involving deep penetration of dye under the bracket base.

Two-year clinical performance of a nanofiller vs a fine-particle hybrid resin composite.

The aim of the study was to evaluate the clinical performance of the nanofiller resin composite Filtek Supreme (3M ESPE) vs the conventional fine hybrid resin composite Tetric Ceram (Ivoclar Vivadent) in stress-bearing posterior cavities. In accordance with a split mouth study design, 50 patients (35.7+/-11.3 years) received at least one pair of Filtek Supreme and Tetric Ceram restorations in each of two comparable class II cavities. To obtain comparability, the adhesive Scotchbond 1 was used for all the restorations. After 2 years, the restorations (total number 112) were scored according to the Ryge criteria. After 2 years (recall rate 100%), the results (%) of the Ryge evaluation for the two groups Filtek Supreme/Tetric Ceram were marginal adaptation: Alfa 96/96, Bravo 2/2, Charlie 2/0, and Delta 0/2; anatomic form: Alfa 98/98, Bravo 0/0, and Charlie 2/2; secondary caries: Alfa 100/100 and Bravo 0/0; marginal discoloration: Alfa 98/100, Bravo 2/0, and Charlie 0/0; surface: Romeo 95/95, Sierra 4/4, Tango 0/0, and Victor 2/2; and color match: Oscar 46/57, Alfa 50/39, Bravo 2/4, and Charlie 2/0. One Tetric Ceram and one Filtek Supreme restoration showed fractures that needed restorative intervention. No severe postoperative sensitivities were reported within the observation period. All restored teeth remained vital; the integrity of all the teeth was scored Alfa. After 2 years, no statistically significant differences (Wilcoxon-Mann-Whitney test) was found between the two restorative materials investigated. Therefore, Filtek Supreme, based on a new nanofiller technology, has proved efficaciousness for clinical use in stress-bearing posterior cavities.

Clinical study on the effectiveness and side effects of hexetidine and chlorhexidine mouthrinses versus a negative control.

OBJECTIVES: The aim of this clinical, controlled double-blind trial was to evaluate the effectiveness and side effects of two different mouthrinses. METHOD AND MATERIALS: Ninety subjects with gingivitis (or slight periodontitis) were randomly allocated to three groups: group 1, Chlorhexamed (0.1% chlorhexidine); group 2, Hexoral (0.1% hexetidine); and group 3, a placebo-control compound. The subjects were instructed on how to use the mouthrinse. At baseline, as well as after 2 and 4 weeks, the Approximal Plaque Index (API), the Bleeding Index (BI), the Community Periodontal Index of Treatment Needs, the Gingival Index (GI), and the Discoloration Index (DI), were measured. Statistical analysis was carried out with the Kruskal-Wallis test, Fisher's exact test, and Wilcoxon test. RESULTS: In group 1, the mean API improved significantly (P < or = .001) after 4 weeks. The mean BI was reduced significantly, as was the GI. In group 2, the mean API and the mean BI both decreased significantly, and a statistically significant reduction of the GI was also seen. In group 3, significant improvements of the mean values of all parameters were documented after 4 weeks. When comparing group 3 with groups 1 and 2, the difference in the reduction of the API was statistically significant (P < .002). No statistical difference could be shown when comparing groups 1 and 2. Regarding the improved results of the BI and the GI, no statistically significant difference was found in the effectiveness of all 3 compounds. All 3 groups showed some increase in the mean DI after 4 weeks. Comparing groups 1 and 2 directly, the difference in the increase in the discoloration of the teeth was statistically significant (P = .0035). There was no statistical difference in the mean discoloration scores comparing groups 2 and 3. CONCLUSION: This double-blind clinical trial demonstrated Hexoral to be a useful alternative to Chlorhexamed mouthrinse, as well as one causing less discoloration.

Survey of the effectiveness of masking noises during dental treatment--a pilot study.

OBJECTIVE: The aim of this study was to test the effectiveness of a newly developed system, using masking noises with specific frequencies and amplitudes, adjusted to typical noises experienced during dental treatment such as the high-speed hand-held drill. METHOD AND MATERIALS: In accordance with an analysis of typical noises experienced during dental treatment, masking noises with specific frequencies (frequency range 0.02 to 20 kHz) and amplitudes were created, with the aim of reducing the patients' awareness of typical treatment noises by overlaying frequencies. Two hundred fifty-four outpatients (113 males, 141 females) with a mean age of 32 years (+/- 10.5 years) were enrolled in this study. Patients were treated 15 minutes with and 15 minutes without the masking noise. Patients and practitioners filled out questionnaires aimed to evaluate the effectiveness of the system, sensitivity to noise (scale 0 to 10; 0 = effective, 10 = noneffective), psychologic aspects, and statements of fear. RESULTS: There was a significant reduction in patients' awareness of noise using this system during dental treatment. Most of the patients regarded the masking noise as a pleasureable supplementation to common treatment and would select this manner of dental treatment employing the device again (81.5%); 48.2% said they were more relaxed. The system does not, in principle, interfere with dental treatment, and in most instances, the device does not impede the communication between practitioners and patients. CONCLUSION: The present study demonstrates that using masking noises during dental treatment reduces the sensitivity to drill noise, reduces fear and stress, and may be useful in dental practice as an adjunct to common dental treatment.

In vivo validation of the historical in vitro thermocycling temperature range for dental materials testing.

In dental research, restorative materials have been regularly subjected to alternating in vitro thermal stress in investigations since the 1950s, in order to simulate in vivo alternating temperature stress and to artificially stress them in vitro. The provocation temperature is mostly 5 degrees C for cold provocation, and 55 degrees C for hot provocation. These temperatures are determined quite arbitrarily based on very few examinations in vivo. Extensive temperature data for the approximal space of teeth, which is decisive for the success of fillings adhesively attached to dentin, has so far not been addressed. The objective of this study was to examine the interproximal temperature characteristics created in the space of all teeth in vivo with thermal alternating stress, and therefore to validate the in vitro standardized thermal alternating stress of 5-55 degrees C. Fifteen study participants with healthy teeth were used to determine the temperature in each inter-dental space, resulting from hot/cold provocation in the upper and lower jaw, from the central incisor to the second molars. This was performed by a thermal element (cable sensor GTF 300, Greisinger Electronic GmbH, Regenstauf, Germany). The temperature sensor was attached with dental floss into the interproximal space and the temperature was recorded by the computer. The participants in the pilot test had to state when they were able to sip an 85 degrees C hot drink. That particular temperature value was taken for hot provocation as maximum temperature reference. Cold ice water (0 degrees C) was used for cold provocation as minimum temperature reference. The respective recordings with a total of 14 measurements for each individual were performed simultaneously in the upper and lower jaw. The study participants were to start with hot provocation, followed by cold provocation. This cycle was repeated at least once with an individual dwell time. The highest recorded approximal space temperature was 52.8 degrees C in the lower jaw, between the first and the second premolar. The lowest temperature of 13.7 degrees C was recorded in two participants in the upper jaw, between the 1st and 2nd incisor, and between the two central incisors. The mean of the maximum temperatures was 43.8+/-3.7 degrees C, and the mean of the minimum temperatures 24.2+/-4.6 degrees C. The mean initial temperature was 35.2+/-1.3 degrees C. None of the recordings reached either the upper threshold (55 degrees C) or the lower threshold (5 degrees C). This study showed that the actual thermal stress in the interproximal space of teeth is slightly lower than the one used in in vitro examinations. For class II cavities, most of the alternating temperature stress limits selected at 5-55 degrees C cover the actually occurring temperature interval quite well.

Marginal integrity of self- and total-etching adhesives in two different application protocols.

PURPOSE: The aim of this study was to evaluate the marginal integrity of four self-etching adhesives (Prompt L-Pop III, Resulcin Aqua Prime & MonoBond N, AC Bond, AC Bond + Desensitizer) and three total-etch adhesives (Opti-Bond FL, Excite, Gluma Comfort Bond) in two different application protocols. MATERIALS AND METHODS: Standardized MOD cavities (n = 40) were prepared in 280 extracted human teeth (one cervical margin in cementum, one in enamel). In one application protocol, the adhesive was applied prior to placement of the Tofflemire matrix (n = 20); in the other, the metal matrix was placed first (n = 20). Light curing was carried out from the occlusal aspect. After thermocycling (5000 times, 5 degrees C and 55 degrees C), specimens were immersed in 2% methylene blue for 10 s. Then the median percentages of dye-penetrated margins (surface analysis) were determined separately for the cervical cementum, cervical enamel, and lateral enamel margins of the proximal boxes. RESULTS: At the cervical cementum margins, statistically significantly worse results were obtained for all adhesives when the matrix system was placed prior to application of the adhesive. In the cervical enamel margins, OptiBond FL, Gluma Comfort Bond, and Prompt L-Pop III performed significantly better when the adhesive was applied prior to the matrix. On lateral enamel margins, only OptiBond FL and Resulcin Aqua Prime showed significantly less dye penetration if the matrix was placed first. CONCLUSION: Most of the total-etch materials produced marginal integrity significantly superior to that of the majority of the self-etching materials. Due to a significant influence of the application protocol on marginal integrity, it is strongly recommended to apply the adhesive system before placement of the matrix.

Two-year clinical performance of a packable posterior composite with and without a flowable composite liner.

The aim of the study was to evaluate the clinical performance of a packable fine hybrid dental composite (Prodigy Condensable) and the influence of the additional application of a flowable resin composite (Revolution, SDS Kerr) layer on marginal integrity after 2 years in stress-bearing posterior cavities according to the Ryge criteria. In 50 patients (40.5+/-17.5 years of age), 116 class II fillings (metal matrix system, glass ionomer-cement-base in 36%, rubberdam isolation in 70%) were placed, with at least two restorations per patient. The adhesive Optibond Solo Plus was used for all the restorations. In one of the two fillings in each patient, an additional layer of the flowable composite Revolution was applied in the entire cavity and separately light-cured. Baseline scores have been rated Alfa in > or =95% and Bravo in <5%. After 2 years, the results [%] of the Ryge evaluation for the two groups with/without the additional use of Revolution were: (1) Marginal Adaptation: Alfa:78/70, Bravo:16/27, Charlie:0/0, Delta:6/4; (2) Anatomic Form: Alfa:89/95, Bravo:6/2, Charlie:6/4; (3) Secondary Caries: Alfa:98/100, Bravo:2/0; (4) Marginal Discoloration: Alfa:76/68, Bravo:24/32, Charlie:0/0; (5) Surface: Alfa:90/91, Bravo:4/5, Charlie:0/0, Delta:6/4; (6) Color Match: Oscar:56/57, Alfa:44/39, Bravo:0/4, Charlie:0/0. Within the observation period (recall rate: 95%), three restorations out of 116 at baseline fractured, one restoration showed a secondary caries, one tooth received endodontic treatment, and all other restored teeth remained vital. After 2 years, no statistically significant difference (Chi-square test) in the overall survival rate between the group with the additional use of Revolution (92.8%) and that without Revolution (94.6%) was found. The combined survival rate for both groups together was 93.7% of clinically acceptable restorations.