Journal of Dental Biomaterials
Volume:2 Issue: 1, 2015

Bioactive glasses are silicate-based and can form a strong chemical bond with the tissues. These biomaterials are highly biocompatible and can form a hydroxyapatite layer when implanted in the body or soaked in the simulated body fluid. Due to several disadvantages, conventional glass processing method including melting of glass components, is replaced by sol-gel method with a large number of benefits such as low processing temperature, higher purity and homogeneity and therefore better control of bioactivity. Bioactive glasses have a wide range of applications, particularly in dentistry. These glasses can be used as particulates or monolithic shapes and porous or dense constructs in different applications such as remineralization or hypersensitivity treatment. Some properties of bioactive glasses such as antibacterial properties can be promoted by adding different elements into the glass. Bioactive glasses can also be used to modify different biocompatible materials that need to be bioactive. This study reviews the significant developments of bioactive glasses in clinical application, especially dentistry. Furthermore, we will discuss the field of bioactive glasses from beginning to the current developments, which includes processing methods, applications, and properties of these glasses.

Statement of Problem: Bitewing radiograph is the main reference for diagnosis of proximal and recurrent caries. There is no software for gathering and analyzing radiologists’ opinion in the field of caries detection on digital bitewing radiograph (DBR). The main aim of this study is to introduce the first windows application that could be used for marking caries on DBR. This software is called Dental Caries Marking Software (DCMS). The second aim is to create the first DBR caries dataset to be used for future software development projects in the field of automatic caries detection; also gathering and documenting the disagreements and critiques regarding DCMS. DCMS has been designed and implemented by the researchers of this study. This software is divided into two parts. The first part is DCMS writer that is used for gathering the user’s opinion and The second part is DCMS analyzer that is used for reading and analyzing the user’s opinion file. Eight radiologists with different experiences used DCMS for marking dental caries on 200 DBR, 50 of which were repeated twice for assessing the accuracy of each radiologist. A total of 3833 points were marked by 8 users on 150 non repetitive DBR. Only 35 points were marked similarly by 8 users; in other words, 8 users totally agreed with 4% of the caries points. According to 50 repetitive DBR, the maximum accuracy of users was 69% and the minimum was 50%. There is significant debate over the diagnosis of caries on DBR; therefore, for unifying the radiologist’s opinions, the need for intelligent caries detection software is apparent. DCMS is useful software for gathering caries data. Moreover, the use of conventional display monitor has negative impacts on accurate diagnosis of caries on DBR.

Statement of Problem: Tooth-coloured restorative materials are brittle with the major shortcomings of sensitivity to flaws and defects. Although various mechanical properties of resin composites have been studied, no fracture toughness test data for nano-hybrid composites under acidic condition for a long period of time has been published. To compare the fracture toughness (KIc) of two types of resin composites under tensile loading and to assess the effect of distilled water and lactic acid on the resistance of the restoratives to fracture after three months of immersion. Four resin composites were used: three nano-hybrids [EsteliteSigma Quick (Kuraray), Luna (SDI), Paradigm (3M/ESPE)] and one hybrid, Rok (SDI). The specimens were prepared using a custom-made polytetrafluorethylene split mould, stored in distilled water (pH 6.8) or 0.01mol/L lactic acid (pH 4) and conditioned at 37°C for 24 hours, 1 or 3 months. They were loaded under tensile stress using a universal testing machine; the maximum load (N) to the specimen failure was recorded and the fracture toughness (KIc) was calculated. Data were analysed by ANOVA and Tukey’s test using SPSS, version 18. The results of two-way ANOVA did not show a significant combined effect of material, time, and storage medium on fracture toughness (p= 0.056). However, there was a strong interaction between materials and time (p=0.001) when the storage medium were ignored. After 24 h of immersion in distilled water, Paradigm revealed the highest KIc values followed by Rok, Luna and Estelite. Immersion in either distilled water or lactic acid significantly decreased the fracture toughness of almost all materials as time interval increased. Paradigm showed the highest fracture toughness followed by Rok, Luna and Estelite respectively. As time increased, KIc significantly decreased for almost all resin composites except for Luna which showed a slight decrease after one month of immersion in distilled water.

Statement of Problem: Accurate impressions are one of the most critical factors in achieving acceptable restorations. When pouring the impressions of implant supported restorations, soft materials like silicone and polyether are used to reconstruct the gingival form around the implants. To the best of our knowledge, no study has been conducted on the comparison of the accuracy of these soft materials. To evaluate the accuracy of polyether and silicone in reproducing the correct depth of gingival sulcus around the implants by probing. By the use of a periodontal probe, the gingival height was measured in six marked areas of one maxillary partial edentullism model on which two fixture analogs were attached and three points were marked around each analog for measurements, which was considered as an index height. Addition silicone impression material (putty and wash) was used to simultaneously take 10 impressions of the model. The samples were randomly divided into two groups of 5 and each impressions was poured twice; for the first group, the impressions were first poured with silicone, and for the second one they were poured with polyether material for reproducing the gingival contour; in the second group, the procedure was performed in reverse. Therefore, there were 10 casts in each group and because each cast contained two analogues, and each analogue was marked in three points for measuring gingival height, 60 numbers were achieved for each group as the gingival height. The mean gingival heights were compared by paired t-test using SPSS software, version 18 (p = 0.05). Comparison of the mean gingival height of the silicone and control groups revealed that there was no significant difference between the two groups (p = 0.090), whereas, a significant difference was found between the mean gingival height of the polyether and control groups (p = 0.034). Within the limitation of this study, it was concluded that for reproducing the gingival height around the implants, silicone materials are more appropriate than polyether ones.

Statement of Problem: Disinfection of dental impressions is a weak point in the dental hygiene chain. In addition, dental office personnel and dental technicians are endangered by cross-contamination. This study aimed to investigate the dimensional stability of two color-changing irreversible hydrocolloid materials (IH) after disinfection with glutaraldehyde. In this in vitro study, impressions were made of a master maxillary arch containing three reference inserts on the occlucal surface of the left and right maxillary second molars and in the incisal surface of the maxillary central incisors. Two types of color-changing irreversible hydrocolloid (tetrachrom, cavex) were used. Glutaraldehyde 2% was used in two methods of spraying and immersion to disinfect the impressions. The control group was not disinfected. Casts were made of type IV gypsum. The linear dimensional change of the stone casts was measured with a profile projector. For statistical analysis, Kruskall-Wallis and Mann-Witney tests were used (α=0.05). By immersion method, the casts fabricated from tetrachrom were 0.36% larger in the anteroposterior (AP) and 0.05% smaller in cross arch (CA) dimensions; however, the casts prepared after spraying of tetrachrom were 0.44% larger in the AP and 0.10% smaller in CA dimensions. The casts made from Cavex were 0.05% smaller in the AP and 0.02% smaller in CA dimensions after spraying and 0.01% smaller in the AP and 0.003% smaller in CA dimensions after immersion. Generally there were not significant differences in AP and CA dimensions of the experimental groups compared to the control (p > 0.05). Disinfection of the tested color-changing irreversible hydrocolloids by glutaraldahyde 2% did not compromise the accuracy of the obtained casts.

Statement of Problem: Although different types of aesthetic brackets are introduced to orthodontic profession to reduce the complaints about the metallic braces, little studies have been done to assess patient''s views regarding the attractiveness and acceptance of such brackets. The goal of this study was to evaluate the perceived acceptability, beauty and value of different orthodontic brackets. In a cross-sectional study, three groups of subjects consisting of dental school clinic patients, specialty clinic patients, and art students were interviewed. Sample size was decided 116 in each group. The photographic images of six types of brackets which were placed in an adult mouth were shown to the subjects and they were asked to answer the questions that evaluate attractiveness by visual analog scale (VAS), acceptability of different brackets, and willingness to pay (WTP) for an aesthetic bracket in comparison to a regular bracket. Reliability was measured by giving questionnaires to 20 respondents by a two-week interval. VAS rating was compared by ANOVA. Mann U Whitney and Chi-square tests were used to compare the acceptability between groups when necessary. The reliability measurement results performed by ICC were 0.86 for attractiveness, 0.6 for acceptability, and 0.93 for WTP questions. Lingual brackets had the highest attractiveness rating while metal brackets were considered the lowest aesthetic appliance by all groups of the study. The acceptability of ceramic bracket was highest in all groups. While most appliances evaluated had average acceptability, the large metallic brackets were rated very low. WTP for aesthetic braces was higher in art students than other groups. Lingual brackets were the most attractive but had very low acceptability rate. Small metal brackets had a good acceptability rate. Large metal brackets were the least attractive and had the lowest acceptability. Parents accepted aesthetic brackets for their children even when it cost more.