Analysis of the Pulpal Blood Flow Microdynamics during Prosthetic Tooth Preparation Using Diamond Burs with Different Degrees of Wear.

Pulpal modifications taking place during prosthetic tooth preparation using worn-out burs may represent a risk for the vitality of the dental pulp. The aim of this in vivo study was to evaluate whether the wear of diamond burs has an influence on the vascular microdynamics at the level of the dental pulp, during vertical preparation for zirconia crowns. The study was performed with a split-mouth design and included 32 vital permanent monoradicular teeth (20 maxillary and 12 mandibular), from six subjects, aged between 20 and 50 years. The teeth were randomly assigned to two study groups of 16 teeth each. For prosthetic preparation, new burs were used in the first group, and burs at their 5th use were used in the second group. Four consecutive determinations of the pulpal blood flow by Laser Doppler flowmetry (LDF-laser Doppler MoorLab instrument VMS-LDF2, Moor Instruments Ltd., Axminster, UK) were taken for each tooth included in the study: before the preparation (control values), immediately, at 24 h, and at 7 days after the prosthetic preparation. A four-way ANOVA statistical analysis was applied to analyze the effect of four considered factors (bur wear degree, time of measurement, tooth number, and tooth location) on the pulpal blood flow (PBF). A significant increase in pulpal blood flow compared to the baseline was recorded immediately after preparation (p < 0.01), at 24 h (p < 0.01), and at 7 days (p < 0.05) in both groups, but more pronounced in the case of burs at the 5th use. The blood flow was significantly higher in upper jaw teeth, irrespective of the measurement time. In conclusion, the use of worn-out diamond burs produces lasting modifications in the pulpal blood flow of teeth that undergo prosthetic crown preparation. ISRCTN registry: ISRCTN49594720.

Evaluation of the Pulp Chamber Temperature during Tooth Veneer Preparation Using Burs with Different Degrees of Wear-A Preliminary In Vitro Study.

The heat produced during tooth preparation could be a source of damage for dental pulp, and many variables are involved in this process. The aim of this in vitro study was to evaluate whether the different degrees of wear of the diamond burs significantly influenced the temperature changes in the pulp chamber during tangential veneer preparation. The sample comprised 30 intact permanent monoradicular teeth, randomly assigned to three study groups of 10 teeth each, of which 5 had the pulp tissue preserved and 5 had thermoconductive paste in the pulp chamber. For prosthetic preparation, we used new burs in the first group, burs at their fifth use in the second group, and burs at their eighth use for the third group. The pulp chamber temperature was evaluated at the start, after one minute, and after three minutes of preparation, using a k-type thermocouple. The results of the three-way ANOVA and Tukey post hoc comparisons showed a highly significant effect of the time of measurement, while the pulp condition and the degree of wear of the burs had no effect. In conclusion, the different degrees of wear of conventional diamond burs do not produce statistically significant different changes in the pulp chamber temperature.

Titanium implant surface roughness after different implantoplasty protocols: A laboratory study.

OBJECTIVE: To compare the surface roughness of sandblasted, large grit, acid-etched (SLA) surfaced titanium discs, after implantoplasty (IP) with different combinations of rotating instruments without or with the subsequent use of a silicone polisher. METHODS: Titanium discs (n = 12 per group) with an SLA surface were treated with the following IP protocols: (1) Tungsten carbide bur sequence from company 1 (Komet Dental) without or with polishing (P) with a silicone polisher (Brownie®), (2) tungsten carbide bur sequence from company 2 (Hager & Meisinger GmbH) without or with P, and (3) diamond bur sequence (125, 40, 15-µm grit) without or with P. Pristine turned (T) and SLA titanium discs were used as negative and positive controls, respectively. Surface roughness measurements were taken with a contact profilometer rendering Ra and Rz values. RESULTS: All IP protocols, even without P, resulted in significantly reduced surface roughness compared to the SLA group. The tungsten carbide bur protocols, even without P, resulted in a surface roughness similar to or significantly lower than that in the T group in terms of Ra and Rz , respectively. IP with the diamond bur sequence resulted in a significantly rougher surface compared to that achieved with the carbide burs. In all IP groups, P with a silicone polisher resulted in a significantly smoother surface. CONCLUSIONS: IP with dedicated tungsten carbide burs without or with the subsequent use of a silicone polisher resulted in a surface roughness similar to or significantly lower than that of commercially available turned surfaces. IP with a diamond bur sequence required additional polishing to achieve a comparable surface roughness to that of commercially available turned surfaces.

Characterization and toxicity evaluation of air-borne particles released by grinding from two dental resin composites in vitro.

OBJECTIVE: The project aims to evaluate whether inhalation of particles released upon grinding of dental composites may pose a health hazard to dentists. The main objective of the study was to characterize the dust from polymer-based dental composites ground with different grain sized burs and investigate particle uptake and the potential cytotoxic effects in human bronchial cells. METHODS: Polymerized blocks of two dental composites, Filtek™ Z250 and Filtek™ Z500 from 3M™ ESPE, were ground with super coarse (black) and fine (red) burs inside a glass chamber. Ultrafine airborne dust concentration and particle size distribution was measured real-time during grinding with a scanning mobility particle sizer (SMPS). Filter-collected airborne particles were characterized with dynamic light scattering (DLS) and scanning electron microscopy (SEM). Human bronchial epithelial cells (HBEC-3KT) were exposed to the dusts in dose-effect experiments. Toxicity was measured with lactate dehydrogenase (LDH) assay and cell counting kit-8 (CCK8). Cellular uptake was observed with transmission electron microscopy (TEM). RESULTS: Airborne ultrafine particles showed that most particles were in the size range 15-35 nm (SMPS). SEM analysis proved that more than 80% of the particles have a minimum Feret diameter less than 1 µm. In solution (DLS), the particles have larger diameters and tend to agglomerate. Cell toxicity (LDH, CCK8) is shown after 48 h and 72 h exposure times and at the highest doses. TEM showed presence of the particles within the cell cytoplasm. SIGNIFICANCE: Prolonged and frequent exposure through inhalation may have negative health implications for dentists.

CAD/CAM diamond tool wear.

OBJECTIVE: This study evaluated the wear of computer-aided design/computer-assisted manufacture (CAD/CAM) burs and the morphologic changes after a number of millings. METHOD AND MATERIALS: Diamond burs (cylinder and step-bur) were divided into four milling groups: zero millings (G0); 15 millings (G1); 25 millings (G2); and 35 millings (G3). Seventy-five premolar crowns were milled using the Cerec Compact Milling unit and VitaBlock Mark II. Surface roughness, three-dimensional profile, and SEM were used for wear and surface damage evaluation. RESULTS: Two-way ANOVA and Tukey test (α = .05) showed that G3 produced statistically different values compared to G0 and G2, but not G1. The cylinder burs showed higher roughness values than step-burs for all groups. SEM showed similar diamond particle damage for cylinder burs and step-burs, and signs of surface damage, cracks, and particle losses for G3. CONCLUSION: Both cylinder burs and step-burs were able to sustain a larger number of milling procedures than indicated by the manufacturer.

Comparison of cutting efficiency with different diamond burs and water flow rates in cutting lithium disilicate glass ceramic.

BACKGROUND: This study compared different diamond burs and different water flow rates on the cutting efficiency of sectioning through lithium disilicate glass ceramic. METHODS: The authors used a standardized cutting regimen with 4 brands of diamond burs to section through lithium disilicate glass ceramic blocks. Twelve diamonds of each brand cut through the blocks in randomized order. In the first part of the study, the authors recorded sectioning rates in millimeters per minute for each diamond bur as a measure of cutting efficiency. In the second part of the study, the authors compared sectioning rates using only 1 brand of diamond bur, with 3 different water flow rates. RESULTS: The authors averaged and compared cutting rates of each brand of diamond bur and the cutting rates for each flow rate using an analysis of variance and determined the differences with a Tukey honest significant difference test. One diamond bur cut significantly slower than the other 3, and one diamond bur cut significantly faster than 2 of the others. The diamond bur cutting efficiency through lithium disilicate glass ceramic with a 20 mL/min water flow rate was significantly higher than 15 mL/min. CONCLUSIONS: There are differences in cutting efficiency between diamond burs when sectioning lithium disilicate glass ceramic. Use a minimum of 20 mL/min of water coolant flow when sectioning lithium disilicate glass ceramic with dental diamond burs to maximize cutting efficiency. PRACTICAL IMPLICATIONS: Recommendations for specific diamond burs with a coarse grit and water flow rate of 20 mL/min can be made when removing or adjusting restorations made from lithium disilicate glass ceramic.

Cutting efficiency of diamond burs operated with electric high-speed dental handpiece on zirconia.

Zirconia-based dental restorations are becoming used more commonly. However, limited attention has been given to the difficulties experienced, concerning cutting, in removing the restorations when needed. The aim of the present study was to compare the cutting efficiency of diamond burs, operated using an electric high-speed dental handpiece, on zirconia (Zir) with those on lithium disilicate glass-ceramic (LD) and leucite glass-ceramic (L). In addition, evaluation of the cutting efficiency of diamond burs on Zir of different thicknesses was performed. Specimens of Zir were prepared with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm, and specimens of LD and L were prepared with a thickness of 1.0 mm. Cutting tests were performed using diamond burs with super coarse (SC) and coarse (C) grains. The handpiece was operated at 150,000 rpm with a cutting force of 0.9 N. The results demonstrated that cutting of Zir took about 1.5- and 7-fold longer than cutting of LD and L, respectively. The SC grains showed significantly higher cutting efficiency on Zir than the C grains. However, when the thickness of Zir increased, the cutting depth was significantly decreased. As it is suggested that cutting of zirconia is time consuming, this should be taken into consideration in advance when working with zirconia restorations.

Decontamination methods used for dental burs - a comparative study.

AIMS AND OBJECTIVES: Infection control and modes of sterilizations are the key factors to avoid cross transmission of infection in the field of dentistry. Transmission of disease or infection is noted with improper sterilization of reused instruments. Dental burs are the most important tool in any endodontic or conservative procedures of teeth involving tooth contouring, restorative filling procedures and endodontic procedures. Hence, the present study is undertaken to assess the efficacy of different methods of sterilization or decontamination which are routinely used in dental clinics. MATERIALS AND METHODS: For the present study 96 round diamond burs were selected and divided into 6 groups. These burs were used for the access cavity preparation to get contamination and subjected for bacteriological culture. After getting base line date burs were subjected to manual scrubbing, hot air oven, glass bead sterilizer, ultrasonic cleaner and autoclave to get post decontamination data. RESULTS: The study revealed that mean colony forming units/ml of Streptococcus mutans decreased maximum for autoclave with 80% reduction, for Lactobacilli 76% reduction and for Candida albicans maximum reduction seen for glass bead sterilizer with 74%. CONCLUSION: Findings of our study revealed that none of the methods used were found to be absolutely efficacious in the decontamination of dental burs. However, among the experimental groups used in the present study, autoclave was found to be the relatively best method.

An Epidemiological Study on the Selection, Usage and Disposal of Dental Burs among the Dental Practioner's.

AIM: The purpose of this cross sectional study was to understand and evaluate local practioner's knowledge on dental bur selection, its usage, sterilization procedures undertaken and the method of disposal of dental burs in restorative procedures. MATERIALS AND METHODS: A Questionnaire proforma was prepared with each question having 4 answers. A total of 20 questions were framed and were sub-divided in to 3 categories namely selection, usage sterilization and disposal. These Questionnaire were sent to all the local practioner's by mail and to ensure a high response rate as they were followed up by telephone calls. The results were analyzed statistically and were represented in the form of percentage. RESULTS: A total 131 out of 150 practioner's answered the questions, a response rate of 87%. Most of the practioner's preferred diamonds (75%) over tungsten carbide (15%) burs. most of the dentists used burs till they were worn out (85%) and many of the dentists agreed that the cutting efficiency of bur decreased with usage (33%). Clinicians usually sterilized burs either once daily (35%) or for every patient (35%). Almost every practioner discarded their worn out burs into dustbin (100%). CONCLUSION: From the survey we came to know the operators attitude towards one group of burs in terms of cutting efficiency. In terms of cutting efficiency diamond burs predominated the choice irrespective of the grit size. Burs were used repeatedly till they were worn out and minimal coolant was used during tooth preparation and believed that it didn't have any effect on the cutting efficiency.

Análise das dimensões padrões das macrogeometrias de pontas diamantadas de diferentes fabricantes e modelos / Analysis of the macrogeometry pattern dimensions of diamond burs of different manufacturers and models

Pontas diamantadas são instrumentos rotatórios abrasivos de uso rotineiro na prática clínica odontológica, com macrogeometria constituída de haste metálica, ponta ativa e eixo Intermediá- rio. Objetivo: avaliar as dimensões padrões dos componentes que constituem a macrogeometria das pontas diamantadas. Material e Método: a fim de padronização, considerou-se como ponta ativa a região do instrumental que possui granulação; como eixo Intermediário a região compreendida entre a primeira depressão presente na base até o início da ponta ativa; e como haste metálica toda região localizada entre a base da ponta diamantada até a primeira depressão. Realizou os testes com seis marcas comerciais: KG Sorensen, Option, Vortex, Microdont, Zeep e Fava. Foram selecionadas 120 pontas diamantadas tronco-cônicas, modelos 2200 (n=10) e 2135 (n=10). O diâmetro e comprimento foram analisados em sete regiões correspondentes à macrogeometria. O diâmetro do orifício de encaixe de pontas diamantadas em turbinas de alta rotação de cinco marcas (Gnatus, Kavo, Calu, Dx e Dabi) também foi mensurado. Para realizar as medidas, paquímetro digital (Mitutoyo, modelo número 6, C-B) foi utilizado por um único operador calibrado. Resultado: as dimensões de ambos os modelos de pontas diamantadas apresentaram variação, quando comparado os fabricantes, seja no comprimento total da haste metálica, eixo intermediário ou ponta ativa. A marca comercial KG Sorensen apresentou baixa alteração na dimensão entre seus instrumentos. Conclusão: a não padronização das pontas diamantadas pode prejudicar a confecção de preparos e também o aprendizado de estudantes de odontologia.

Diamond burs are abrasive rotary instrumental routinely used in clinical dentistry practice with macro geometry consists of metal stem, the active tip and intermediate shaft. Objective: evaluate the standardized dimensions of the components that constitute the macro geometry of the diamond bur. Methods: in order to standardize, it was considered as active tip the area of the diamond bur that has granulation; as intermediate the region between the first depression at the base until the beginning of the active tip; and as stem all region located between the base of the diamond tip to the first depression. The test was performed with six brand: KG Sorensen, Option, Microdont, FAVA, Zeep, Vortex. 120 trunk-conical diamond burs, models 2200 (n = 10) and 2135 (n = 10) were selected. The diameter and length were evaluated in seven regions corresponding to macro geometry. The diameter of the diamond bur orifice fitting on the high speed turbines of five brands (Gnatus, Kavo, Calu, Dx and Dabi) were also measured. A digital caliper (Mitutoyo, modelo número 6, C-B) was used for measurements by a single calibrated operator. Results: the dimensions of both models showed variation compared trademarks, either in the total length of the metal stem, active tip or intermediary. KG Sorensen trademark presented low alterations in size between their instruments. Conclusion: the non-standardized of diamond burs can hamper the confection of preparations and also the learning of dental students.

CVD (Chemical Vapor Deposition) - solução para controle de temperatura durante preparo cavitário? / CVD (Chemical Vapor Deposition) - solution for control of temperature during cavity preparation?

Os procedimentos restauradores em Odontologia utilizam brocas, turbinas de alta rotação, laser e novas tecnologias, como as pontas diamantadas obtidas pelo processo de deposição química a vapor (CVD). O uso incorreto desses métodos pode gerar aquecimento excessivo e agredir o complexo dentinopulpar, provocando lesões que variam de leve à grave e até mesmo a necrose da polpa. O objetivo deste trabalho foi revisar e discutir o aumento de temperatura no complexo dentinopulpar durante o preparo cavitário, causado pelas brocas diamantadas convencionais usadas em turbina de alta rotação, pelo laser e pelas pontas diamantadas CVD acopladas ao ultrassom. Treze estudos foram encontrados após busca na base de dados PubMed no período de 1998 a 2009, sendo quatro relacionados a brocas diamantadas em turbinas de alta rotação, sete acerca de sistemas a laser e dois sobre as pontas CVD. De acordo com a literatura científca pesquisada, pode-se concluir que nenhum dos métodos aumenta a temperatura a ponto de causar injúria pulpar irreversível. Porém, não há estudos suficientes publicados para se afirmar que as pontas diamantadas CVD apresentam-se como a solução para controle do aumento de temperatura durante o preparo cavitário.

The restorative procedures in dentistry use burs, high-speed handpieces, laser and new technologies such as diamond burs obtained by the process of chemical vapor deposition (CVD). The misuse of these methods can generate excessive heat, and harm the pulpodentin complex, causing injuries ranging from mild to severe and even necrosis of the pulp. The objective was to review and discuss the temperature increase in pulpodentin complex during cavity preparation, caused by conventional diamond burs used in high-speed handpieces, laser and the CVD ultrasound diamond burs. Thirteen studies were found after a search on PubMed database from 1998 to 2009, and 4 were related to diamond burs at high-speed handpieces, 7 about laser systems and 2 about the CVD burs. According to the researched literature, we can conclude that none of the methods increases the temperature to the point of causing irreversible injury on the pulp. However, there are not enough published studies that confrm CVD diamond burs as the solution to controlling the temperature increase during cavity preparation.

Avaliação histológica da resposta pulpar humana a diferentes técnicas de instrumentação cavitária e de restauração / Histological evaluation of the human pulp response to different cavity instrumentation and restorative techniques

Este estudo se propõe a analisar a resposta pulpar de dentes humanos a preparos cavitários de classe V, em função de duas diferentes técnicas de instrumentação e de duas diferentes técnicas de restauração. Para tal, cavidades classe V, nas superfícies vestibulares de 48 pré-molares hígidos de pacientes entre 11 e 25 anos, que estavam em tratamento ortodôntico, foram preparadas e restauradas de acordo com os seguintes grupos experimentais: G 1 (n=24) - preparos cavitários realizados com ponta diamantada em alta rotação, restaurados com guta-percha plastificada, cimento ionômero de vidro e verniz cavitário (G 1A; n=12) ou com técnicas adesivas (sistema restaurador adesivo aplicando-se o condicionamento ácido total) e cimento ionômero de vidro (G 1B; n=12); G 2 (n=24) - preparos cavitários com ponta CVD ativada por ultrassom, restaurados com gutapercha plastificada, cimento ionômero de vidro e verniz cavitário (G 2A; n=12) ou com técnicas adesivas (sistema restaurador adesivo aplicando-se o condicionamento ácido total) e cimento ionômero de vidro (G 2B; n=12); e G 3 (controle; n=4) - dentes que foram extraídos sem a realização de qualquer procedimento. Os preparos cavitários foram realizados mantendo o assoalho da cavidade o mais próximo possível da polpa, no entanto, sem provocar exposição pulpar. Os dentes foram extraídos após três períodos experimentais (imediato, sete e trinta dias após o preparo cavitário), fixados, descalcificados, e processados histologicamente. Cortes teciduais longitudinais seriados de 5 m foram obtidos, corados pelas técnicas de H & E e de Brown & Brenn, e examinados em microscopia ótica. As avaliações morfométricas e por escores foram realizadas e os resultados das mesmas, submetidos, respectivamente, aos testes estatísticos de Mann-Whitney e de Kruskal-Wallis/Dunn, adotando-se um nível de significância de 5%. No período inicial, todos os grupos experimentais (1A, 1B, 2A e 2B) exibiram ligeiro desarranjo da camada odontoblástica...

The aim of this study is to analyze the pulp response of human teeth to class V cavity preparation, in function of two different instrumentation and restorative techniques. Class V cavities were made on the buccal surfaces of 48 sound human pre-molars from orthodontic patients from 11 to 25 years, and were divided as follows: G1 (n=24) cavity preparations were made with diamond bur under high speed, restored with either plasticized gutta-percha, glass ionomer cement and surface coated with varnish (G1A) or adhesive protocol (total etch technique and adhesive system application) with glass ionomer filling (G1B); G2 (n=24) cavity preparations were made with diamond CVD point and ultrasonic device, restored with either plasticized gutta-percha, glass ionomer cement and surface coated with varnish (G2A) or adhesive protocol (total etch technique and adhesive system application) with glass ionomer filling (G2B); and control group G3 (n=4) extracted teeth with no previous cavity preparation. All avities were prepared with the cavity floor as close to the pulp as possible, without causing pulp exposure. Teeth extractions were made in three experimental periods (immediate, 7 and 30 days after cavity preparation) and right after extraction they were submitted to histological procedures. Longitudinal tissue serial sections of 5 mm were obtained, H&E and Brown&Brenn stained, and analyzed under optical microscope. Morphometric and score evaluations were carried out and data from both were, respectively, submitted to Mann-Whitney and Kruskal-Wallis/Dunn tests, with 5% significance. Immediately, all experimental groups (1A, 1B, 2A and 2B) exhibited a discrete disorganization of the odontoblastic layer and invasion of the Weil zone. There was no difference between experimental and control groups. At 7-day interval, a decrease of the odontoblastic layer was observed. Many odontoblasts nucleus were seen displaced into the dentinal tubules. Some specimens showed absence...