THE EVALUTION OF STRESS DISTRIBUTIONS IN 3 AND 5 UNIT DENTAL AND IMPLANT SUPPORTED FIXED ZIRCONIA RESTORATIONS: FINITE ELEMENT ANALYSIS

Purpose: In this study, it is aimed to compare the distribution of stress on anchorage and implants in 3-and-5-member-dental and implant supported zirconia restorations by using finite element analysis.Material and Method: Stress distribution formed in anchorage and implants as a result of chewing forces was analyzed in dental and implant (Astra Tech Microthread Osseo Speed, Sweeden) supported models of zirconia restoration with 5-member placed on the numbers of 43, 44, 45, 46 and 47 and with 3-member placed on the number of 45, 46 and 47.  The study was performed through static nonlinear analysis with the three-dimensional finite element analysis method.  Results: The highest and the lowest stress were respectively found on the number of 45 and 47 in 3-member dental supported model. The highest and the lowest stress in 5-membered dental-supported model were respectively found on the tooth of number 45 and on the root apex of the implant of number 43. Stress accumulation was observed in the cervical portion of the implant in implant-supported models. Stress accumulation in the tooth-supported model was found less than in implant-supported modelsConclusion: The extreme forces on the dental and implant-supported restorations with increased members can reduce survival rate of restorations in mouth. To prefer dental implants with larger diameter and longer length along with infrastructure like zirconia to design posterior implant-supported restorations can keep restorations in mouth for longer period

A retrospective evaluation of bifid mandibular canal prevalence of Southeastern Anatolia population by cone-beam computed tomography

Introduction: Bifid mandibular canal (BMC) is often detected incidentally on radiological examination and can be observed in unilateral or bilateral forms. The correct localization of the BMC plays an important role in the prevention of complications such as paresthesia, anesthesia, bleeding, traumatic neuroma, which may occur during or after surgical operations on the mandible such as sagittal split ramus osteotomy, impacted third molar tooth extraction, and dental implant surgery. Objective: This study aims to retrospectively evaluate the prevalence of bifid mandibular canal (BMC) in the Southeastern Anatolian population via Conical Beam Computed Tomography (CBCT). Material and Method: In this retrospective study, CBCT images of 615 patients, who applied to the Department of Oral and Maxillofacial Surgery in the Faculty of Dentistry at Dicle University, Turkey, for various reasons from 2015 to 2020, is evaluated and cases with bifid mandibular canals are examined. The prevalence evaluation is conducted by statistical analyses in terms of sex and laterality. Results: According to the analyses, the BMC prevalence did not constitute a significant difference in terms of the age variable (p>0.05). The incidence of unilateral BMC was higher than bilateral BMC (p<0.05; p=0.016). Additionally, the prevalence of BMC was higher in males compared to females (p<0.05; p=0.008). Conclusion: BMC, which can be detected more easily and frequently via CBCT technology, is an anatomical formation that should be taken into account during oral and maxillofacial practices

Evaluation of stress distribution of a new restorative material and composite resin: a finite-element analysis study

Glass carbomer cement is a new dental material developed from the traditional glass ionomer cements. It has better mechanical and chemical features when compared to the conventional glass ionomer cements. The purpose of this in silico investigation was to examine the influence of glass carbomer and composite resin materials with class I cavity design on stresses happening in the inlay. Finite-element analysis and three-dimensional modelling were used to examine the stress in the glass carbomer and hybrid composite inlays resulting from a 300-N point load on occlusal surfaces. Two different inlay materials, glass carbomer cement and hybrid composite resin, were evaluated. The maximum von Misses stress values in the composite resin inlays were significantly lower than those in the glass carbomer inlays. The results from this study showed that the resistance of the glass carbomer against the forces was higher than that of the composite resin inlays. The stresses were concentrated mostly at similar regions. The obtained results suggest that glass carbomer may be recommended as a preferred filler restorative material in teeth with much structure loss