A comparative study of the pulp chamber preparation in maxillary canines

The effectiveness of three methods of lingual dentin edge removal was evaluated in maxillary canines: Batt burs (group I), Gates-Glidden burs (group II) and manual reamers, Batt burs and Gates-Glidden burs (group III). The results showed better dentin edge removal and degree of conicity in group III.     

Surface and pulp chamber temperature rises during tooth bleaching using a diode laser: a study in vitro

OBJECTIVE: To measure the surface and pulp chamber temperature increases in vitro on upper and lower anterior teeth during a tooth whitening procedure using a diode laser. METHOD: A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Pulp chamber temperature readings were made on upper and lower central incisors, lateral incisors and canines. A diode laser recommended for tooth bleaching was tested at three different power settings (1W, 2W, 3W). Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. RESULTS: The increase in surface temperature readings ranged from 37 degrees C (1W) to 86.3 degrees C (3W) with no bleaching gel present. Pulp chamber temperature increases ranged from 4.3 degrees C (1W) to 16 degrees C (3W). The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. CONCLUSIONS: The increase in the pulp chamber temperature with the laser used at 1-2W was below the critical temperature increase of 5.5 degrees C thought to produce irreversible pulpal damage. However, a power setting of 3W produced a pulp chamber temperature increase above this threshold (16 degrees C) and caution is advised when using this setting.     

电子麻醉对牙髓SP、CGRP阳性纤维的作用

目的：研究电子麻醉镇痛作用的外周机理。方法：用免疫组化方法观察电子麻醉对大鼠牙髓及牙周组织感觉神经肽的影响。结果：电活力测试仪刺激可使被测牙牙髓内SP、CGRP阳性纤维完全脱失,牙周组织及领域牙不受影响。而电子麻醉使被累及的牙齿牙髓中的SP、CGRP阳性纤维数量减少,刺激部位牙龈组织中的SP、CGRP阳性纤维脱失。结论：电活力测试仪刺激仅兴奋牙髓中的感觉神经纤维,而电子麻醉可同时兴奋牙周组织及牙髓中的感觉神经纤维。电子麻醉和电活力测试仪刺激所兴奋的神经纤维可能属于不同的功能亚群,它们的兴奋分别产生镇痛作用的疼痛。     

年轻恒牙牙髓电活力测试的临床研究

目的：研究年轻恒牙电活力试验多出现假阴性的原因。方法：通过对全颌曲面断层X线片上牙根尖孔宽度的测量。比较不同根尖孔宽度的电活力试验结果。结果：根尖孔宽大者，假阴性率高。随着根尖孔宽度减小，电活力试验的准确度提高，它们之间呈负相关。结论：新生恒牙出现电活力试验假阴性是由于根尖孔面积过大，通过根尖部牙髓单位面积的电流强度相对较小，达不到刺激阈值而产生的。     

Beyond冷光牙齿漂白技术对人牙髓影响的组织病理学研究

目的 探讨Beyond冷光牙齿漂白技术对牙髓的影响.方法 选择因正畸要拔除的40颗活髓牙,对照组(10颗)不做任何处理拔除,其余30颗采用Beyond冷光漂白后分别即刻拔除(15颗)和漂白七天后拔除(15颗).40颗牙齿均制作病理切片,镜下观察牙髓组织形态.结果 所有活髓牙漂白前后均未发现有任何临床症状.漂白后即刻拔除组、七天后拔除组以及对照组在镜下均表现为正常的牙髓组织结构,漂白组较对照组牙髓组织无明显改变.结论 Beyond冷光牙齿漂白技术对活髓牙牙髓无明显不良影响,是一项安全可靠的漂白技术.     

Temperature change in the pulp chamber during complete crown preparation.

This study observed the temperature changes in the pulp chamber during tooth preparation for a complete crown. Twelve extracted, morphologically intact human teeth were chosen: four canines, four premolars, and four molars. Six teeth, two of each, were cooled during preparation with an air-water spray; the remaining six were air-cooled. Minimal reduction of dentin using an air-water spray coolant resulted in a lowered temperature in the pulp chamber, mainly with the cross-grooved TDA diamond stones. The application of an air coolant resulted in a temperature rise in the pulp chamber.     

The effect of intentionally perforating the floor of the pulp chamber on pulpal healing after tooth replantation in mice

ObjectivesShortening the root of a mouse molar prior to tooth replantation results in early revascularization in the pulp cavity and activation of the dental pulp quiescent stem cells. This study aimed to validate the effects of pulp chamber floor perforation on pulpal healing after tooth replantation as a strategy to promote early revascularization into the pulp.MethodsThe maxillary first molars of three-week-old Crlj:CD1 mice were extracted and repositioned into the original socket: the left teeth were immediately replanted (control group: CG), whereas the floor of the pulp chamber of the right teeth was perforated with a tungsten carbide bur before tooth replantation (experimental group: EG). The samples were collected from three days to eight weeks postoperatively. In addition to the TUNEL assay, immunohistochemistry for Nestin, CK14, and Ki-67 was conducted.ResultsIn the EG, early revascularization occurred with a decrease in apoptosis and an increase in cell proliferation, facilitating pulpal healing, compared with the CG. The rate of Nestin-positive perimeter in the distal root significantly increased on days 5 and 14 and the amount of Nestin-positive hard tissue increased on day 14. However, on day 7, the number of epithelial cell rests of Malassez in the EG significantly decreased, making the EG susceptible to ankylosis at the floor.ConclusionsIntentionally perforating the floor of the pulp chamber provides a route for early revascularization, resulting in better pulpal healing after tooth replantation.     

牙体预备后牙髓并发症相关因素的研究进展

全冠修复牙体预备过程中的各种刺激,不可避免地对牙髓造成一定损伤,本文分别对牙体预备前、牙体预备过程中及牙体预备后影响牙髓并发症的相关因素进行分析,旨在规范牙体预备的临床操作方法,将损伤降低到牙髓的生理修复范围内。     

Immunohistochemical evaluation of endothelial cell adhesion molecules in human dental pulp: effects of tooth preparation and adhesive application

OBJECTIVE: Studies have demonstrated that restorative procedures can initiate pulpal inflammation. Adhesion molecules on endothelial cells mediate the leukocyte-endothelium interaction, which is the fundamental event of inflammation. The aim of this study was to evaluate possible changes in the endothelial cell adhesion molecules (CAMs) of human dental pulp with tooth preparation, and after the application of one-step self-etch adhesive. MATERIALS AND METHODS: Twenty healthy human premolars and third molars scheduled to be extracted for orthodontic reasons were randomly assigned to four experimental groups. Group 1 involved sound intact teeth representing the controls. In group 2, teeth were prepared for full crown and extracted within 2h. Groups 3 and 4 comprised the teeth coated with one-step self-etch adhesive, iBond Gluma inside following the preparation and extracted after 24 and 48h, respectively. Tissue distribution and staining intensity of CAMs including E-selectin, P-selectin, ICAM-1, VCAM-1 and PECAM-1 was investigated in the pulp samples using monoclonal antibodies and the streptavidin-biotin-horse-radish immunoperoxidase procedure. The assessment of immunohistochemical reactions was performed by two independent observers using a semi-quantitative scale. RESULTS: All the CAMs evaluated were expressed by the healthy pulp tissues. Significant alterations in the distribution and staining intensity of CAMs were detected following tooth preparation. One-step self-etch adhesive tested in the present study induced inflammatory reactions in the pulp (P<0.05, Mann-Whitney U-test). CONCLUSION: It seems evident that tooth preparation for full crown and application of one-step self-etch adhesive on prepared teeth had a potential to interfere with the inflammatory response.     

NaOCl effects on primary and permanent pulp chamber dentin

OBJECTIVES: The dentin quality of primary and permanent pulp chamber was inspected by Fourier-transformed Raman spectroscopy (FT-Raman) and scanning electron microscopy (SEM). Fragments of pulp chamber dentin were obtained from 20 human molar crowns (primary and permanent). METHODS: The fragments were assigned to 8 groups (n=5)-Primary teeth: G1, pulp chamber dentin; G2, pulp chamber dentin irrigated with NaOCl 1% (30min); G3, pulp chamber dentin irrigated with NaOCl 1% (30min) and etched by 35% phosphoric acid; G4, pulp chamber dentin etched by 35% phosphoric acid. Permanent teeth: G5, pulp chamber dentin; G6, pulp chamber dentin irrigated with NaOCl 1% (30min); G7, pulp chamber dentin irrigated with NaOCl 1% (30min) and etched by 35% phosphoric acid; G8, pulp chamber dentin etched by 35% phosphoric acid. The spectra were subjected to the Cluster analysis. The SEM images were scored. RESULTS: Inorganic content: There was a difference between primary and permanent dentin. The groups treated with NaOCl were statistically similar between them, but differed from the groups not treated. Organic content: There was no difference between primary and permanent dentin. The groups became similar after NaOCl and phosphoric acid treatments. The microscopic images showed the presence of calcospherites on permanent dentin and their absence on primary dentin. CONCLUSIONS: The NaOCl changed the inorganic content in both dentitions; regardless of the following phosphoric acid etching. However, the chemical changes caused by NaOCl were not detected by SEM when it was followed by etching.     

In vitro assessment of temperature change in the pulp chamber during cavity preparation

STATEMENT OF PROBLEM: Tooth preparation with a high-speed handpiece may cause thermal harm to the dental pulp. PURPOSE: This in vitro study evaluated the temperature changes in the pulp chamber during 4 different tooth preparation techniques and the effects of 3 different levels of water cooling. MATERIAL AND METHOD: The tip of a thermocouple was positioned in the center of the pulp chamber of 120 extracted Shuman premolar teeth. Four different tooth preparation techniques were compared: (1) Low air pressure plus low load (LA/LL), (2) low air pressure plus high load (LA/HL), (3) high air pressure plus low load (HA/LL), and (4) high air pressure plus high load (HA/HL) in combination with 3 different water cooling rates. Control specimens were not water cooled; low water cooling consisted of 15 mL/min, and high water cooling consisted of 40 mL/min. Twelve different groups were established (n=10). An increase of 5.5 degrees C was regarded as critical value for pulpal health. The results were analyzed with a 3-factor ANOVA and Bonferroni adjusted Mann Whitney U test (alpha=.004). RESULTS: For all techniques without water cooling (LA/LL/0, LA/HL/0, HA/LL/0, and HA/HL/0), the average temperature rise within the pulpal chamber exceeded 5.5 degrees C during cavity preparation (7.1 degrees C; 8.9 degrees C; 11.4 degrees C, and 19.7 degrees C, respectively). When low water cooling was used with high air pressure and high load technique (HA/HL/15), the average temperature rise exceeded 5.5 degrees C limit (5.9 degrees C). However, when high water cooling (LA/LL/40, LA/HL/40, HA/LL/40, and HA/HL/40) was utilized, the critical 5.5 degrees C value was not reached with any air pressure or load (3.1 degrees C, 2.8 degrees C, 2.2 degrees C, and -1.8 degrees C, respectively). CONCLUSION: Within the limitations of this in vitro study, the results indicate that reducing the amount of water cooling or increasing air pressure and load during cavity preparation increased the temperature of the pulp chamber in extracted teeth.     

The emotional effects of tooth loss: a preliminary quantitative study

AIM: To establish how widespread the emotional effects of tooth loss are. METHOD: A questionnaire, distributed to 100 edentulous people undergoing routine prosthetic care in the Department of Prosthetic Dentistry at Guy's, King's and St Thomas' Dental Institute (GKT), was used to explore the emotional effects of tooth loss. RESULTS: Ninety four people completed the questionnaire of whom 42 stated that they had experienced difficulties in accepting the loss of their teeth. In comparison with people who had no difficulties in accepting the situation, these people were: more likely to feel less confident about themselves; more likely to feel inhibited in carrying out everyday activities; and less able to accept the inevitable change in facial shape which occurs following the loss of teeth. Additionally, they took longer to come to terms with their tooth loss (All these differences were statistically significant). Just over three-quarters of the people who were unprepared for the loss of their teeth, felt that an explanation from the dentist prior to dental extractions would have helped. CONCLUSION: The impact that tooth loss can have on people and their lives should not be underestimated. In this study it affected 45% of the participants.