Influence of cavity lining and remaining dentin thickness on the occurrence of postoperative hypersensitivity of composite restorations.

PURPOSE: To investigate the influence of the remaining dentin thickness after cavity preparation, calcium hydroxide lining, and two restorative systems on the occurrence of postoperative pain or hypersensitivity. MATERIALS AND METHODS: One hundred twenty-three fillings were placed in 123 healthy patients. The remaining dentin thickness after caries excavation was measured with the Prepometer device at the deepest area of the cavity. The cavities were allocated to three different groups (shallow, medium, and deep) on the basis of the Prepometer results. The decision to use a calcium hydroxide liner or not was made by tossing a coin. Cavities which were to be later treated with an indirect restoration were restored with a buildup material. The other cavities were treated with a hybrid composite. After 6 months, the patients were re-examined and interviewed concerning postoperative pain incidents or hypersensitivity. A logistic regression was performed for the statistical analysis. RESULTS: Logistic regression showed no statistically significant influence of any of the three different variables "cavity depth", "calcium hydroxide liner" and "restorative material" on the occurrence of pain or hypersensitivity. CONCLUSION: The occurrence of pain or hypersensitivity does not depend on the remaining dentin thickness, calcium hydroxide lining, or the restorative system used in the present study.

Potential of fluoridated carbamide peroxide gels to support post-bleaching enamel re-hardening.

OBJECTIVE: Aim of the in vitro study was to evaluate the time period needed to re-establish enamel surface microhardness after bleaching with fluoridated (0.5% F(-) as NaF) and unfluoridated carbamide peroxide (CP) bleaching gels under a daily de- and remineralization protocol. MATERIALS AND METHODS: Ninety enamel specimens were prepared from bovine incisors and prepared for Knoop microhardness determination. The samples were divided into five groups and bleached for 7 days (8h per day) with experimentally designed neutral and acidic 10% CP gels: A (0.5% F(-), pH 7.0), B (0.5% F(-), pH 5.5), C (no F(-), pH 7.0) and D (no F(-), pH 5.5). Group E served as control and was not bleached. After each 8-h bleaching period the samples were subjected to a de- and remineralization protocol. In the following 5 days, the specimens were not bleached, but stored in artificial saliva for 8h instead; the daily de- and remineralization cycles were maintained during this period. Knoop microhardness determinations were conducted at baseline, after each bleaching interval and after completion of each daily de- and remineralization cycle. A repeated measures two-way ANOVA statistical analysis and a comparison of confidence intervals was conducted to check for hardness recovery during the post-bleaching period. RESULTS: After completion of bleaching therapy on day 7 a statistically significant hardness loss was observed for all bleaching groups in the range of about 7-15% hardness reduction as compared to baseline. The fluoridated gels proved significantly less hardness loss than the unfluoridated gels. In the following period, from days 8 to 12 recovery of hardness to baseline data was observed in the fluoridated groups (A and B) after the first de-/remineralization cycle on day 8 (group A) and after the second 8-h remineralization period on day 9 (group B), respectively. Hardness of the specimens treated with the unfluoridated bleaching gel C returned to baseline values after day 10. The samples of group D did not show recover of hardness data during the 5-day post-bleaching period. CONCLUSION: Fluoridated 10% carbamide peroxide bleaching gels support re-hardening of bleached enamel with a shorter period needed for hardness recover as compared to unfluoridated gels.

Subjectivity and examiner experience in diagnosis of residual caries--an in vitro study.

UNLABELLED: The aim was to evaluate subjectivity (using inter- and intraexaminer repeatability), the effect of examiner experience, and residual caries diagnostic accuracy with visual tactile (VT) criteria and using a caries disclosing agent (CD). Thirty teeth with occlusal caries were excavated by a single operator not involved in the diagnostic part of the study. A test area was marked in each cavity. Four dentists with more than five and five dentists with less than five years' experience rated the marked area twice (a week apart) using VT criteria. A week later, the samples were stained using Caries Detector. The same examiners rated the presence or absence of stain in the marked area twice (a week apart). Undecalcified thin slices were examined for bacteria using light microscopy. Overall kappa for inter-examiner repeatability was higher for CD (0.45) than VT (0.31). In the less experienced group the kappa value was higher for CD (0.41) than for VT (0.23). In the experienced group kappa was lower for CD (0.43) than for VT (0.46). Median kappa for intra-examiner repeatability was higher for caries detector (0.77, 0.53) compared to visual tactile (0.52, 0.34) for the more and less experienced examiners respectively. There was no significant difference between the experienced and the inexperienced group in combined sensitivity and specificity (mean) for VT (0.52, 0.53) or CD (0.60, 0.58). IN CONCLUSION: VT was more subjective than CD, except for experienced examiners who had a higher inter-examiner repeatability for VT than CD. Diagnostic accuracy for residual caries does not increase with experience.

Influence of bleaching agents and desensitizing varnishes on the water content of dentin.

This in vitro study investigated the possible dehydration of dentin caused by bleaching agents. Furthermore, it tested whether protective dentin varnishes can maintain the physiological moisture of dentin during bleaching treatment. Fifty-five standardized dentin cylinders were prepared from freshly extracted bovine incisors under constant water irrigation. Prior to bleaching, the treatment specimens were conditioned at room temperature in a hygrophor for 14 days. The samples were divided into 11 groups. The Group A specimens, which were completely dehydrated, and Group B, which was stored for 2 weeks in a hygrophor, served as controls (A, B n=5). The other samples (n=10 each group) were coated with Vivasens [VS] (C), Bilfuorid [BF] (D) and Seal&Protect [SP] (E). Five specimens from each group (C-E) were subsequently treated with an experimental bleaching gel (Exp BG) (20% carbamide peroxide [CP], glycerine-based gel): Cb, Db, Eb. The remaining specimens were bleached with Exp BG (F) only, Vivastyle (G: 16% CP, glycerine-based gel) or Vivastyle Paint On (H: 6% CP-varnish) for 7 days (n=5 each group) with bleaching time for gels: 2 hours/day, paint on: 20 minutes/day. After the respective treatments, the overall water content of each specimen was determined using the analytical method of Karl-Fischer-titration. The water content of bovine dentin (Group B, mean%+/-SD) obtained in this study amounted to 15.24+/-0.4. All bleaching products significantly reduced the water content compared to the controls (exp BG: 13.32+/-0.47, Vivastyle 13.2+/-0.27, paint on 13.72+/-0.54; p<0.05). Also, application of SP before bleaching resulted in reduced water content (14.06+/-0.12; p=0.0005). However, bleaching with exp BG following use of VS (14.99+/-0.42) or SP (13.85+/-0.26) did not result in a reduction of water content in dentin. Pretreatment with BF did not protect dentin from water loss during bleaching (12.44+/-0.38; bi p=0.0009). All glycerine-based bleaching products used in this study had a significant dehydrating effect on dentin. The application of protective varnishes prior to bleaching treatment may reduce or even prevent dentin dehydration.

Subsurface microhardness of enamel and dentin after different external bleaching procedures.

PURPOSE: To evaluate the influence of various bleaching systems on subsurface microhardness of enamel and dentin. METHODS: 60 bovine crowns were distributed among seven groups (A: Opalescence Xtra Boost, B: Opalescence Quick, C: Rapid White, D: Whitestrips, E: Opalescence 10%, F: Opalescence PF 15%). The crowns were sectioned and baseline hardness (Knoop) of enamel and dentin was assessed on the sectioned surface at various distances from the enamel surface. The sectioned surface was covered with wax and the enamel was treated for 10 days with the bleaching agents A-F according to manufacturers' instructions. Bleaching with C-F was conducted each day (C: twice per day for 10 minutes, D: twice per day for 30 minutes, E: 8 hours, F: 4 hours), systems A-B were applied on first and fifth days (A: twice for 10 minutes, B: 1 hour). Finally, hardness was re-assessed. Data were statistically analyzed to compare baseline hardness and final hardness in the respective groups (P< 0.05). RESULTS: Analysis showed that in Group C, hardness was significantly reduced in both enamel and dentin. In the remaining groups, significant reduction of hardness was observed up to the following depths [microm] in enamel; A: 250, B: 700, D: 300, E: 150, F: 150. In these groups no significant hardness changes were recorded in subsurface dentin.

Influence of disinfectants on dentin bond strength of different adhesive systems.

The influence of water disinfectants used in dental unit waterlines on the dentin bonding of different adhesive systems was investigated by using push-out tests. Three hundred and twenty dentin disc specimens were prepared from caries-free human molars. In each specimen, a standardized conical cavity was prepared while cooling with water from a dental unit containing one of three different disinfectants (n=80 each group; A=control: water without disinfectant, B: Alpron neutral, C: Alpron mint, D: Dentosept P). Subsequent rinsing of the cavities was performed With the respective disinfectant. The cavities were filled with the following combinations of dentin adhesives and composites, resulting in 16 subgroups (n=20): Syntac Classic/Tetric Ceram, Clearfil Liner Bond 2V/Luxacore, OptiBond FL/Prodigy and Prime&Bond NT/Spectrum. After polishing the fillings, one half of each subgroup (n=10) was stored in water (37 degrees C) for 24 hours. The other half was stored in water (37 degrees C) for 180 days and additionally thermocycled (2000 cycles at 5/55 degrees C). The bond strength was then measured by push-out tests. Statistical analysis of the data was carried out using ANOVA and pairwise t-tests (Significance level p < or = 0.01). The disinfectants showed no significant influence on the loads required for debonding of Syntac Classic/Tetric Ceram, Clearfil Liner Bond 2V/Luxacore and OptiBond FL/Prodigy as compared to the controls. However, the use of disinfectants in the water supply of a dental unit decreased dentin bond strength in the specimens filled with Prime&Bond NT/Spectrum. Disinfectants in the water of dental unit waterlines may have an influence on dentin bonding, depending on the adhesive system used.

[Influence of the buffer capacity of amine fluoride-containing toothpastes and gels in enamel erosion]. / Einfluss der Pufferkapazität aminfluoridhaltiger Zahnpasten und Gele bei Schmelzerosionen.

The aim of the study was to evaluate the abrasion resistance of eroded enamel brushed with experimental toothpastes and fluoride gels of varying buffering capacities. 50 Specimens were prepared from extracted human molars and cycled through three alternating de- and remineralizations including brushing abrasion in a brushing machine. Demineralization was accomplished by immersing the samples in 1% citric acid (5 min), remineralization occurred during immersing the samples in artificial saliva (1 min). Groups of ten samples were brushed with either one of the toothpaste (A-C) or one of the fluoridated gels (D-E). Toothpastes and gels were produced on the basis of elmex toothpaste or elmex-gelée (GABA International AG, Switzerland). Amount of titrable acid was defined as amount (mg) of 1 N KOH needed for neutralization of 1 g toothpaste or gel (A: 6 mg, B: 12 mg, C: 24 mg, D: 3.1 mg, E: 10 mg KOH). The following abrasion values (mean + S.D. [micron]) were obtained profilometrically: A: 6.76 +/- 2.05, B: 6.84 +/- 1.19, C: 8.28 +/- 2.89, D: 4.19 +/- 1.09 and E: 0.83 +/- 0.61. No significant difference in abrasion between the toothpastes was found. The fluoride gel with the higher buffering capacity (E) exhibited significantly less abrasion than the gel with the lower buffering capacity (D). It is concluded that in eroded enamel buffering capacity of the tested fluoridated toothpastes has no effect on abrasion, whereas use of fluoride gel with a higher buffering capacity leads to reduced abrasion values.

Comparative study of p63 and p53 expression in tissue microarrays of malignant melanomas.

p63 is a known homologue of p53. In contrast to p53, however, p63 mutations are rarely seen in tumours. There have been several reports that p63 plays a regulatory role in the normal differentiation of cells, whereas its role in tumour biology must still be elucidated. The main aim of this study was to compare p63 and p53 expression in tissue microarrays of malignant melanomas and to establish any prognostic significance. p63 expression was found in 2 out of 59 tumours, both pT4. The p63 index did not exceed 30%. p53 expression was found in 27 out of 59 melanomas, with maximal expression in up to 80% of tumour cells. There were no correlations observed between the two markers. Multivariate analysis confirmed the prognostically independent role of p53. This study also confirmed that tissue microarrays can be used effectively for evaluation of the expression of certain tumour markers.