Finite element analysis on the optimal material choice and cavity design parameters for MOD inlays exposed to different force vectors and magnitudes

WOS: 000386328700002This simulation study evaluated the effect of three different inlay materials (composite, glass ceramic, zirconia), cavity design parameters (isthmus width and depth) and different force vectors and magnitudes on the stress distribution within mesio-occlusal-distal (MOD) inlays and the remaining enamel and dentin. The mechanical performance of inlays was evaluated using 3-D finite element analysis (FEA) method. Three different restoration materials and hard tissues of the restored tooth with different cavity depth (2-5mm) and width (2-4mm) were exposed to occlusal loading with different magnitudes from 10 to 130kg at varying angles between 0 degrees and 15 degrees. The maximum von Mises stresses were calculated for the inlays, tooth structure and bonded surfaces. Response Surface Optimization method was implemented into the finite element software package in order to design cavity shapes with more favourable interfacial stresses for bonded restorations under occlusal loading. Teeth restored with resin composite exhibited the highest von Mises Stress, followed by glass ceramic and zirconia. The increase in isthmus width decreased interfacial shear stresses in zirconia MOD inlay but the increase in cavity depth did not change the stress levels for all three materials. According to mechanical safety factor, inlay and tooth structure remained within the mechanical limits in three parameters (material, magnitude of force, cavity shape) but negatively affected by the force vector

Effect of material and fabrication technique on marginal fit and fracture resistance of adhesively luted inlays made of CAD/CAM ceramics and hybrid materials

WOS: 000386328700006This study evaluated the fracture resistance and marginal fit of CAD/CAM ceramic and composite inlays. Molars (N=80) were prepared to receive Mesio-occlusal-distal (MOD) inlays and randomly divided into four groups to be restored depending on the materials: (a) HLD: heat-pressed lithium disilicate ceramic (IPS e.max Press), (b) CLD: CAD/CAM-fabricated lithium disilicate ceramic (IPS e.max CAD), (c) NC: CAD/CAM nano-ceramic resin (Lava Ultimate), (d) RC: Indirect resin composite (Filtek P60). Each group was randomly divided into two subgroups regarding the resin cement: (a) High-viscosity resin cement (Syntac, Variolink II), (b) Self-adhesive low-viscosity cement (RelyX Ultimate). After marginal gap and cement thickness measurements, specimens were loaded to fracture in a Universal Testing Machine (1mm/min). Intact molars acted as the control group (n=10). Data were analyzed using one-way and two-way ANOVA, Tukey's tests (=0.05). Before cementation, CLD group showed significantly lower mean marginal gap (65 +/- 22.4m) and after cementation, cement thickness was again the lowest with CLD (82.6 +/- 24.6m) and the highest with HLD (108.4 +/- 21.3m) (p0.05)

Marginal Bone Loss Around Early-Loaded SLA and SLActive Implants: Radiological Follow-Up Evaluation Up to 6.5 Years

PURPOSE The aim of this study was to compare marginal bone loss around early-loaded SLA and SLActive tissue-level implants (Straumann Dental Implants; Institut Straumann AG, Basel, Switzerland) after a mean of 81-month follow-up period. MATERIAL AND METHODS One hundred seven SLA and 68 SLActive implants were placed in 55 patients and loaded with final restoration after 8 and 3 weeks of healing time, respectively. Marginal bone loss around implants was determined radiographically at initial and after a mean observation time ranging between 20 and 81 months. The effect of location (mandible vs maxilla), smoking habit, sex, implant length and diameter, and the type of prosthesis on the marginal bone loss was evaluated. RESULTS The overall cumulative survival rate was 98.2% being 99% for SLA implants and 97% for SLActive implants. After 20-month follow-up period, mean marginal bone loss values for the SLA and SLActive implants were 0.24 and 0.17 mm, respectively. After 81 months, mean marginal bone loss for the SLA and SLActive implants reached 0.71 and 0.53 mm, respectively. Marginal bone loss was affected by the length and type of implant and patients' smoking habit after a mean observation time of 20 months. However, none of the parameters had any significant effect on the marginal bone loss after a follow-up period of 81 months. CONCLUSION With both SLA and SLActive implants, successful clinical results could be achieved up to 6.5 years of follow-up period

Multidisciplinary Treatment Approach in a Patient with History of Nasopharyngeal Carcinoma

Radiotherapy in NPC patients has side effects on the dentition, which affects quality of life dramatically. This case report presents multidisciplinary dental treatment approach in a 17-year-old male patient with a history of nasopharyngeal carcinoma (NPC), which was treated with chemotherapy and radiotherapy. The adolescent patient applied to dental hospital 4 years after the radiotherapy with aesthetic and functional problems on dentition affecting psychological, social, and physical aspects of his life. The dentition of the patient demonstrated the severe destruction as a devastating side effect of radiotherapy. With a successful multidisciplinary approach, our patient’s aesthetics, function, and self-confidence were obtained. Well-established procedures, which include preventative care and maintenance, can reduce the duration and expenses of the treatment and help in challenging the life-long complications of radiotherapy