Tayfun Özdemir

Accuracy of Two Stereolithographic Guide Systems for Computer-Aided Implant Placement: A Computed Tomography-Based Clinical Comparative Study

BACKGROUND Stereolithographic surgical guides provide significant benefits during the simultaneous placement of multiple implants with regard to the final prosthetic plan. However, deviation from the planning poses a significant risk. Deviations of implants that were placed by bone-, tooth-, and mucosa-supported stereolithographic surgical guides were examined in this study. METHODS After enrolling 54 eligible patients, 294 implants were planned on cone-beam computerized tomography CB(CT)-derived images. Sixty guides, both single- and multiple-type, were produced using two commercial systems. Mucosa-supported guides were fixed with osteosynthesis screws. Implants were inserted, and at the end of osseointegration period, a new CB(CT) scan was performed. Preoperative planning was merged with the new CB(CT) data to identify the deviations between the planned and placed implants for each support type and manufacturer. The Kruskal-Wallis and Mann-Whitney U tests were used for comparison (P <0.05). RESULTS There were no damage-related complications in any critical anatomy. Implants that were placed by bone-supported guides had the highest mean deviations (5.0 degrees +/- 1.66 degrees angular, and 1.70 +/- 0.52 mm and 1.99 +/- 0.64 mm for implant shoulder and tip, respectively), whereas the lowest deviations were measured in implants that were placed by mucosa-supported guides (2.9 degrees +/- 0.39 degrees angular, and 0.7 +/- 0.13 mm and 0.76 +/- 0.15 mm for implant shoulder and tip, respectively). CONCLUSIONS Computer-aided planning and manufacturing surgical guides in accordance with CB(CT) images may help clinicians place implants. Rigid screw fixation of a single guide incorporating metal sleeves and a special drill kit further minimizes deviations.

Evaluation of 316 narrow diameter implants followed for 5-10 years: a clinical and radiographic retrospective study.

OBJECTIVES Narrow diameter implants (NDIs; diameter >3.75 mm) are useful in replacement of missing incisor teeth and when the bucco-lingual width of the edentulous crest is insufficient. The present study evaluated the success and survival rates, peri-implant parameters, mechanical and prosthetic post-loading complications of NDIs followed over a 10-year period. MATERIAL AND METHODS Three hundred and sixteen NDIs were inserted into 139 patients and restored with 120 prostheses. Clinical and radiographic assessment data were collected during recall visits. Implant success (SC), cumulative survival rate (CSR), marginal bone loss (MBL), peri-implant conditions and prosthetic complications were assessed. Cox proportional hazards regression analysis, Kaplan-Meier survival curves with the log-rank test and life table analysis were used to evaluate the outcome of NDIs within comparable subgroups. MBL and peri-implant parameters measured annually were further analyzed. RESULTS The mean follow-up time was 9.1 years (range: 60-124 months). Twelve implants were lost in the healing phase and two during function. The mean MBL in the maxilla and the mandible was 1.32 +/- 0.13 and 1.28 +/- 0.3 mm, respectively, after 10 years. SC and CSR were 91.4% and 92.3%, respectively, after 124 months. Smoking and posterior localization were associated with an increased risk of failure. Cement loosening (16.8%) was the most common prosthetic complication. No implants were fractured. CONCLUSIONS NDIs can be used with confidence where a regular diameter implant is not suitable. MBL around NDIs occurred predominantly within 2 years of loading and was minimal thereafter. Further studies are required to clarify the possible risks associated with smoking and posterior placement.

Implant surgery using bone‐ and mucosa‐supported stereolithographic guides in totally edentulous jaws: surgical and post‐operative outcomes of computer‐aided vs. standard techniques

OBJECTIVES The aim of this study was to compare the surgical and post-operative outcomes of a computer-aided implant surgery performed by bone- and mucosa-supported stereolithographic (SLA) guides against the standard technique. MATERIAL AND METHODS Multiple- and single-type SLA guides from two commercial manufacturers were produced and a total of 341 implants were placed to 52 patients using the standard technique (Control group), bone- (bone-supported guide [BSG] group) and mucosa-supported SLA guides (Flapless group) in 21, 16 and 15 patients, respectively. Surgical duration (min), number of analgesics (tablets) as well as hemorrhage, difficulty in mouth opening (or trismus) and other incidences were recorded. Pain and swelling was assessed using the visual analog scale (VAS). Parametric and non-parametric tests were used for statistical analysis (P<.05). RESULTS The mean surgery duration (23.53+/-5.48 min) and the number of analgesics consumed (four tablets) in the Flapless group were lower than those in the control (68.71+/-11.4 min and 10 tablets) and BSG groups (60.94+/-13.07 min and 11 tablets, P<0.01). The change in pain scores (VAS) and the number of analgesics consumed in time were statistically significant (P<0.01 and 0.05, respectively) and the Flapless group reported a lower pain score than the BSG (P<0.01) and Control groups (P<0.001). The Flapless group experienced less hemorrhage (chi(2)=4.12, P=0.041 on the day of surgery) and fewer instances of trismus (chi(2)=6.91, P=0.031 the day after surgery). The differences in early-term failures were not statistically significant between the groups (log-rank test: P=0.782). CONCLUSION The use of mucosa-supported single SLA guides for flapless implant placement may help reduce the surgery duration, pain intensity, related analgesic consumption and most other complications typical in the post-implant surgery period. However, there are particular drawbacks in both guide types and further studies are required to confirm the prosthodontic conformity and long-term success of implants placed using computer-assisted techniques.

Conventional multi-slice computed tomography (CT) and cone-beam CT (CBCT) for computer-assisted implant placement. Part I: relationship of radiographic gray density and implant stability.

PURPOSE The relationship of conventional multi-slice computed tomography (CT)- and cone beam CT (CBCT)-based gray density values and the primary stability parameters of implants that were placed by stereolithographic surgical guides were analyzed in this study. MATERIALS AND METHODS Eighteen edentulous jaws were randomly scanned by a CT (CT group) or a CBCT scanner (CBCT group) and radiographic gray density was measured from the planned implants. A total of 108 implants were placed, and primary stability parameters were measured by insertion torque value (ITV) and resonance frequency analysis (RFA). Radiographic and subjective bone quality classification (BQC) was also classified. Results were analyzed by correlation tests and multiple regressions (p < .05). RESULTS CBCT-based gray density values (765 ± 97.32 voxel value) outside the implants were significantly higher than those of CT-based values (668.4 ± 110 Hounsfield unit, p < .001). Significant relations were found among the gray density values outside the implants, ITV (adjusted r(2)  = 0.6142, p = .001 and adjusted r(2)  = 0.5166, p = .0021), and RFA (adjusted r(2)  = 0.5642, p = .0017 and adjusted r(2)  = 0.5423, p = .0031 for CT and CBCT groups, respectively). Data from radiographic and subjective BQC were also in agreement. CONCLUSIONS Similar to the gray density values of CT, that of CBCT could also be predictive for the subjective BQC and primary implant stability. Results should be confirmed on different CBCT scanners.

Conventional multi-slice computed tomography (CT) and cone-beam CT (CBCT) for computer-aided implant placement. Part II: reliability of mucosa-supported stereolithographic guides.

PURPOSE Deviations of implants that were placed by conventional computed tomography (CT)- or cone beam CT (CBCT)-derived mucosa-supported stereolithographic (SLA) surgical guides were analyzed in this study. MATERIALS AND METHODS Eleven patients were randomly scanned by a multi-slice CT (CT group) or a CBCT scanner (CBCT group). A total of 108 implants were planned on the software and placed using SLA guides. A new CT or CBCT scan was obtained and merged with the planning data to identify the deviations between the planned and placed implants. Results were analyzed by Mann-Whitney U test and multiple regressions (p < .05). RESULTS Mean angular and linear deviations in the CT group were 3.30° (SD 0.36), and 0.75 (SD 0.32) and 0.80 mm (SD 0.35) at the implant shoulder and tip, respectively. In the CBCT group, mean angular and linear deviations were 3.47° (SD 0.37), and 0.81 (SD 0.32) and 0.87 mm (SD 0.32) at the implant shoulder and tip, respectively. No statistically significant differences were detected between the CT and CBCT groups (p = .169 and p = .551, p = .113 for angular and linear deviations, respectively). CONCLUSIONS Implant placement via CT- or CBCT-derived mucosa-supported SLA guides yielded similar deviation values. Results should be confirmed on alternative CBCT scanners.

Bacteremia following dental implant surgery: Preliminary results

Objectives: The aims of this study were to investigate the incidence of bacteremia, bacteriology and antibiotic susceptibility against to causative bacteria associated with dental implant installation. Study Design: 30 generally healthy patients were enrolled in this study. Blood samples were collected at baseline and at 30 minutes after dental implant installation and 24 hours after dental implant surgery. Blood samples were cultured in a BACTEC system. The isolated bacteria were identified using conventional methods. Antimicrobial sensitivity tests were performed by disc diffusion. Results: No bacteria were isolated at the baseline and 24 hours after surgery, whereas the prevalence of bacteremia at 30 minutes after dental implant installation was 23%. The isolated bacteria species were Staphylococcus epidermidis, Eubacterium spp., Corynebacterium spp. and Streptococcus viridans. The Staphylococcus epidermidis, which was isolated in three patients, was found to be resistant to penicillin which is first choice of many clinicians. Conclusion: Our findings suggest that installation of dental implants can produce bacteremia. Within the limitations of this study, it can be speculated that the resistance of antibiotics may compromise the routine prophylaxis against infective endocarditis. Therefore use of blood cultures and antibiograms may be suggested in risky patients. The outcome of the present study should be verified using a larger patient group with varying conditions. Key words: Dental implant, bacteremia, infective endocarditis, antibiotic prophylaxis.

Antibacterial activity of As-annealed TiO2 nanotubes doped with Ag nanoparticles against periodontal pathogens

It is important to develop functional transmucosal implant surfaces that reduce the number of initially adhering bacteria and they need to be modified to improve the anti-bacterial performance. Commercially pure Ti sheets were anodized in an electrolyte containing ethylene glycol, distilled water and ammonium fluoride at room temperature to produce TiO2 nanotubes. These structures were then annealed at 450°C to transform them to anatase. As-annealed TiO2 nanotubes were then treated in an electrolyte containing 80.7 g/L NiSO4 ·7H2O, 41 g/L MgSO4 ·7H2O, 45 g/L H3BO3, and 1.44 g/L Ag2SO4 at 20°C by the application of 9 V AC voltage for doping them with silver. As-annealed TiO2 nanotubes and as-annealed Ag doped TiO2 nanotubes were evaluated by SEM, FESEM, and XRD. Antibacterial activity was assessed by determining the adherence of A. actinomycetemcomitans, T. forsythia, and C. rectus to the surface of the nanotubes. Bacterial morphology was examined using an SEM. As-annealed Ag doped TiO2 nanotubes revealed intense peak of Ag. Bacterial death against the as-annealed Ag doped TiO2 nanotubes were detected against A. actinomycetemcomitans, T. forsythia, and C. rectus indicating antibacterial efficacy.

Relative Contributions of Surface Roughness and Crystalline Structure to the Biocompatibility of Titanium Nitride and Titanium Oxide Coatings Deposited by PVD and TPS Coatings

This study was conducted to characterize titanium (Ti) metal surfaces modified by polishing, coating with titanium nitride, coating with titanium oxide, sandblasting with alumina (Al2O3) particles and coating with titanium oxide, coating with titanium plasma spray (TPS); and to evaluate the effect of surface roughness and crystalline structure on adhesion of human fetal osteoblast cells (CRL-11372) in vitro after 24 hours. Surface topography and roughness were examined by scanning electron microscopy (SEM) and a noncontacting optical profilometer, respectively. The crystalline structures of the coatings were characterized by X-ray diffraction (XRD). CRL-11372 cells were incubated at these surfaces for 24 h and were evaluated for their mean total cell counts and cell viabilities. Cell morphologies were examined qualitatively by SEM images. Glass discs served as control group (CG) for the cell culture experiments. Surfaces at the Group TPS had the highest and values. Highest mean total cell counts were found for the CG. SC (sandblasted and TiO2 coated) surfaces had shown sparsely oriented CRL-11372 cells while other surfaces and CG showed confluency. Surfaces displayed diverse crystalline structures. Crystalline structures led to different cellular adhesion responses among the groups regardless of the surface roughness values.

Sinus Augmentation With Platelet-Rich Fibrin in Combination With Bovine Bone Graft Versus Bovine Bone Graft in Combination With Collagen Membrane

The purpose of this study was to compare the efficacy between the use of bovine bone graft material and platelet-rich fibrin (PRF) mixture (test group) and bovine bone graft material and collagen membrane combination (control group) in 2-stage maxillary sinus augmentation. According to specific inclusion/exclusion criteria, patients treated between 2008 and 2012 were selected. Panoramic radiographs were used for radiologic assessments. To evaluate the relationship between sinus-graft height and each implant, the bone level (BL) was divided by implant length (IL). To evaluate the change in the height of grafted sinus, the grafted sinus floor above the lowest part of the original sinus height (GSH) was divided by the original sinus height (OSH). Samples taken during implant surgery were used for histologic and histomorphometric analyses. Twenty-five patients, 32 augmentation surgeries, and 66 one-stage implants were included in the study. No implant loss or complication was observed in either group. There were no statistical differences according to new bone formation (P = .61) and biomaterial remnant (P = .87). During the evaluation period, the test group showed statistically less change in the BL/IL ratio (P = .022). The difference of GSH/OSH ratio was found to be insignificant between groups (P = .093). It was observed that the grafted sinus covering the implant apex and sinus floor was above the original sinus height in both groups. It may be concluded from this study that both combinations can be successfully used for sinus augmentation. Further studies evaluating different graft materials and PRF combinations in the early phases of healing would be beneficial.

Effects of Surface Modifications with Oxalic Acid Etching and Sandblasting on Surface Topography and Biocompatibility of cpTi Surfaces

ABSTRACT The objective of this study was to evaluate the topographical effects of titanium surfaces created by sandblasting and oxalic acid etching on the adhesion of human fetal osteoblast cells (CRL-11372) in vitro after 24 hours. Osteoblast cells were cultured on polished titanium (Ti) discs (Control Group), alumina (Al2O2) particle blasted and oxalic acid etched (20 min) Ti discs, oxalic acid etched polished Ti discs for 20 min, and oxalic acid etched Ti discs for 60 min. The topographies and roughness of the modified surfaces were assessed. Cell count, cell viability and morphologic differences between cells adhering to the modified surfaces were evaluated. The results showed that all surfaces, independent of surface roughness, favored cell adhesion with similar cell viabilities to that of the positive control group cells after 24 h. The highest Ra (average roughness) value was found for sandblasted and oxalic acid etched surfaces as 4.54 μm. Acid etching with 10 % oxalic acid after sandblasting did not eliminate residual alumina particles. Surface modification processes ended up with similar mean total cell counts with each other, even exhibiting no differences from the positive control group in terms of their cell viabilities. Oxalic acid etching and sandblasting surface treatments represented in our study increased the surface roughness values and allowed adhesion of the CRL-11372 cells after 24 h of incubation.