Polyetheretherketone (PEEK) material is a polycyclic, aromatic, thermoplastic polymer that is semi-crystalline and has a linear structure. PEEK has good mechanical and electrical properties such as resistance to high temperature and resistance to hydrolysis. In addition, because of the property of high biocompatibility, use of PEEK has increased in orthopaedic and trauma cases. The most characteristic property of PEEK material is that it has a low elasticity modulus, close to that of bone. It has been suggested that stress-based problems could be reduced with this material due to the low elasticity modulus. In the light of this information, PEEK material could be considered as an alternative to conventional materials in the field of dentistry.

Together with developments in digital imaging systems, there has been increasing use of micro-computed tomography (μCT) in many areas, primarily in dentistry. As this method allows 3-dimensional images to be taken providing safe and high quality results, without damaging the samples being examined, it is often preferred. Consequently, it has become possible to record rapid progression in endodontic studies in particular and to research and easily compare several techniques. Furthermore, this method can be used in tissue engineering, forming data for FEM analysis, the growth and development of craniofacial bones, imaging bone structure, and in the evaluation of implants and surrounding bone in root tip surgery, to determine mineral concentration in the teeth and to measure the thickness of enamel. The aim of this review was to focus on the areas of use of μCT in dentistry and state the advantages. Key Words: Micro-computed tomography, X-ray micro-CT, dental application, three-dimensional imaging How to cite this article: Erpaçal B, Adıgüzel Ö, Cangül S. The use of micro-computed tomography in dental applications. Int Dent Res 2019;9(2):78-91. Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Aim: This study aimed to evaluate the effects on microleakage of the application of ozone gas, laser and traditional cavity disinfection under in vitro conditions. Material and Methods: Ninety third-molar teeth extracted for various reasons were used in this study. All the teeth were prepared with a standard V cavity on the buccal surface. Then the teeth were randomly allocated to one of 6 groups of 15 teeth; Group 1 benzalkonium chloride, Group 2 chlorhexidine gluconate, Group 3 sodium hypochloride, Group 4 diode laser, Group 5 ozone gas, Group 6 control group- no disinfection was applied. Primer was applied to the cavities, then bond and 10-s polymerization. Clearfil AP-X was used in the cavities as a hybrid composite and polymerized for 20 s. The samples then underwent 1000 thermal cycles of 30-s application, in baths at temperatures between 5 ± 2 °C and 55 ± 2 °C. All the samples were stirred in 0.5% basic phuxine solution and the sections taken under stereomicroscope were examined and photographed at 15 × magnification. SEM analysis was made and the obtained results were statistically evaluated with the Kruskal–Wallis test. Results: No significant difference was seen between the groups in respect of the microleakage values of both the occlusal and gingival edges (p < 0.05). Comparison of the microleakage values of the occlusal and gingival edges of the groups determined the least leakage to be in the ozone group (p < 0.05). Conclusion: No statistical significance was determined between the groups. However, the mean least microleakage was found in the ozone group and the highest amount in the control group.

Objectives: The aim of this study was to compare the water absorption and water solubility of four different composte resin materials. Materials and methods: A total of 40 cylindrical discs were prepared and polymerised with light, as 10 from each group, each sample 2mm in depth and 8mm in diameter. The samples were kept for 24 hrs in a dessicator until a stable weight was reached. Then, the weight of each sample was measured on highly sensitive scales. To calculate the water absorption and solubility, measurements were made again with the sensitive scales at the end of 1, 7 and 30 days. The data obtained were evaluated with One-Way ANOVA variance analysis and the Friedman test. Results: As a result of the statistical analyses, significant differences were determined between the composite resins in respect of water absorption on days 7 and 30 and in respect of solubility on day 30 only. Conclusions: It can be concluded that the negative mechanical, physical and biological effects created by the water absorption and water solubility factors of restorative materials are important issues that should be taken into consideration.

Aim: Metal-supported ceramics as crown material and glass fibre posts as dental post materials are in frequent current use. In recent years, it has been claimed that stress-based biomechanical problems in dentistry can be resolved with the benefit of the low elasticity modulus of polyetheretherketone (PEEK) material. The aim of this study was to use finite element analysis (FEA) to compare the stresses formed by forces applied after the use of PEEK material as dental post and crown material as an alternative to glassfibre posts and metal-supported ceramic crowns. Material and Method: The stress analysis metthod used in this study was FEA. First, micro-computed tomography (micro-CT) images were obtained of a maxillary central incisor tooth and the data of the post materials scanned with a 3-dimensional (3D) laser scanner were uploaded to a computer program. 3D models were obtained with designs made in the computer program of all the materials. The modelling of a maxillary central tooth was completed using 2 different post materials (glassfibre and PEEK) and 2 different crown materials (metal ceramic and PEEK) and 4 groups were formed for analysis. By applying force of 100N at 135˚ from the absolute central point of the palatinal surface of the tooth, the stress values and distribution occurring in the 3D peiodontal models were compared. Results: The use of PEEK post reduced the stresses occurring on the periodontal ligament (PDL) and the cortical bone, and caused no significant change in the stresses on the crown. The use of PEEK crown reduced the stresses occurring on the crown and increased the stresses occurring on the PDL and cortical bone. Conclusion: With further in vitro and clinical studies of PEEK material, it can be considered that within a short time PEEK post and PEEK crown could be in routine use in dentistry.