Effect of pulpal floor perforation repair on biomechanical response of mandibular molar: A finite element analysis.

Background: Evaluation of the biomechanical response of tooth with perforation repair is important to attain predictable prognosis. It may remain altered even after perforation repair due to the loss of tooth structure. Aim: The aim of this study is to assess and compare the effect of pulpal floor perforation repair of different sites with biodentine, on the biomechanical response of mandibular molar through 3-dimensional (3D) finite element analysis (FEA). Materials and Methods: Five different 3D models were constructed based on the site of perforation on the pulpal floor using cone-beam computed tomographic images of an extracted mandibular molar. Perforation size was standardized and simulated to be repaired with calcium silicate-based cement. A force of 200 N was applied simulating normal occlusal loads. Static linear FEA was performed using the Ansys FEA software. Tensile stresses were evaluated (Pmax). Statistical Analysis Used: The data were evaluated using the independent t-test (P = 0.05). Results: All the simulated models with perforation repair exhibited higher stress values than their equivalent sites in the control group. The Pmax values of the repaired models were highest in central furcal perforation, followed by buccal furcal perforation. However, there was no statistically significant difference in the stress accumulation among the different repaired perforation sites. Conclusion: The site of the pulpal floor perforation affected the stress distribution and accumulation. Central and buccal furcal perforation repairs on the pulpal floor with calcium silicate-based cement in mandibular molar are likely to have an increased risk of fracture.

Comparison of apical debris extrusion during root canal preparation using instrumentation techniques with two operating principles: An in vitro study.

AIMS: The aim of this study was to quantify the debris extruded apically from teeth using rotary and reciprocation instrumentation systems. SUBJECTS AND METHODS: Eighty extracted human mandibular premolars with single canals and similar lengths were instrumented using ProTaper Universal (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), and Reciproc (R40; VDW GmbH, Munich, Germany). Debris extruded during instrumentation was collected into preweighed Eppendorf tubes, which were then stored in an incubator at 70°C for 5 days. The final weight of the Eppendorf tubes with the extruded debris was calculated after obtaining the mean of three consecutive weights obtained for each tube. STATISTICAL ANALYSIS USED: Statistical analysis was performed using SPSS version 16.0 software. The groups were compared using the Kruskal-Wallis test for all variables. RESULTS: There was no statistically significant difference between the groups (P = 0.1114). However, the ProTaper Universal group produced more extrusion and ProTaper Next produced least debris extrusion among the instrument groups (P > 0.05). CONCLUSIONS: All instrumentation techniques were associated with extruded debris.

Randomized, placebo-controlled study of the efficacy of a calcium phosphate containing paste on dentin hypersensitivity.

OBJECTIVE: Hypersensitivity of non-carious cervical lesions (DH) is a frequently encountered disease. This randomized, controlled, single-blind crossover study evaluated the effectiveness of a calcium phosphate containing desensitizer paste (TAP) on DH in comparison to water as placebo (PLA). METHODS: In this clinical trial 35 patients were randomly assigned to the test and the negative control group. Using a 10cm long VAS (visual analog scale) patients should respond with DH score >6 on one tooth in each of two quadrants for allocation. Pain stimuli were a 2-seconds air blast (AB) and probe scratching (PS) of the exposed dentin. VAS scores were determined pre-operatively (PRE), immediately after treatment (POST), at 1 week, 1, 3 and finally after 6 months. RESULTS: Both TAP and PLA applications decreased DH significantly at POST and throughout the 6-months recalls (p<0.001). Pain reductions upon AB stimulation of TAP treated teeth, assessed at POST and 6 months were 35 and 55%, upon PS stimuli 21 and 54%, respectively. PLA treated lesions responded to AB at POST and after 6 months with 20 and 36% pain reduction, to PS with 11 and 30% pain reduction, respectively. Differences between TAP and PLA pain scores were statistically significant at all recalls (p<0.05). SIGNIFICANCE: TAP paste reduced DH successfully during this 6-months trial. The calcium phosphate crystallites included in the paste and the presumed hydroxyapatite precipitates upon exposure to saliva were hypothetically able to occlude open dentinal tubules, at least to some extent. TAP is considered a biocompatible desensitizer paste.

Randomized controlled clinical trial on the efficacy of dentin desensitizing agents.

OBJECTIVE: To investigate the effects of four dentin desensitizers on pain reduction in hypersensitive cervical dentin lesions. MATERIALS AND METHODS: The trial was designed as a randomized, controlled, four-arm, single-masked study. Fifty subjects with at least one hypersensitive lesion in each of the four quadrants were allocated. The requested pre-operative pain, determined as a response to 2-s air-blast (AB) and probe scratching (PS), was ≥5 on a VAS scale, 0 = no through to 10 = worst pain. Randomly each subject received each of the four treatments: MS Coat One F (MSC, Sun Medical, Japan), Nanoseal (NAN, Nishin, Japan), Teethmate Desensitizer (TMD, Kuraray Noritake, Japan) and Gluma Desensitizer PowerGel (GLU, HeraeusKulzer, Germany). The investigator assessed blindly the pain response using the two stimuli and recorded the patients' VAS scores before and immediately after application, after 1 week and after 1, 3 and 6 months. STATISTICAL DATA TREATMENT: ANOVA and post-hoc testing (p ≤ 0.05). RESULTS: Forty-nine subjects completed the trial. Pre-operative dentin hypersensitivity (DH) for the groups was not significantly different. All desensitizers reduced DH significantly throughout the 6-months observation. ANOVA revealed significant differences among VAS scores, obtained with the desensitizing agents (p < 0.001). Ranking by post-hoc testing was: MSC > NAN > TMD > GLU (p < 0.05). Upon PS NAN and TMD showed slight but significant regain of sensitivity after 6 months. For GLU PS scores immediately after application and after 6 months were not significantly different, whereas recalls after 1 week, 1 month and 3 months revealed significantly lower scores. CONCLUSION: The calcium phosphate-based TMD and GLU proved highly effective in reducing sensitivity.