Tolga F. Tözüm

Biomechanical aspects of primary implant stability: a human cadaver study.

BACKGROUND The quality of bone is an important factor in the successful implant treatment, and it is evident that higher implant failure is more likely in poor quality of bone. The primary stability of oral implants related to resistance to micromotion during healing is influenced by bone quality, surgical technique, and implant design. PURPOSES The aims of this biomechanical study were to explore the effect of bone quality on initial intraosseous stability of implants, and to determine the correlations between the bone quality and implant stability parameters. MATERIALS AND METHODS Twenty-four implants (Neoss Ltd., Mölnlycke, Sweden) were placed into anterior and posterior regions of three human cadaver mandibles. The bone densities of implant recipient sites were preoperatively determined using computerized tomography (CT) in Hounsfield unit (HU). The maximum insertion torque values were recorded, and primary implant stability measurements were noninvasively performed by means of resonance frequency analysis (RFA). RESULTS The bone density values ranged from -267 HU to 553 HU. It was found that mean bone density, insertion torque, and RFA values were 113 +/- 270 HU, 41.9 +/- 5 Ncm, and 70 +/- 7 implant stability quotient (ISQ), respectively. Statistically significant correlations were found between bone density and insertion torque values (r = 0.690, p < .001); bone density and ISQ values (r = 0.557, p < .05); and insertion torque and ISQ values (r = 0.853, p < .001). CONCLUSION CT is a useful tool to assess bone quantity and quality in implant recipient sites, and bone density has a prevailing effect on implant stability at placement.

Location of posterior superior alveolar artery and evaluation of maxillary sinus anatomy with computerized tomography: a clinical study

OBJECTIVES Knowledge and evaluation of the maxillary sinus anatomy before sinus augmentation are essential for avoiding surgical complications. Posterior superior alveolar artery (PSAA) is the branch of maxillary artery that supplies lateral sinus wall and overlying membrane. The aims of this study were to examine the prevalence, diameter, and location of the PSAA and its relationship to the alveolar ridge and to study the prevalence of the sinus pathology and septum using computerized tomography (CT) scans. MATERIALS AND METHODS One hundred and twenty-one CT scans (242 sinuses) from patients undergoing sinus augmentation procedure and/or implant therapy were included. Lower border of the artery to the alveolar crest, bone height below the sinus floor to the ridge crest, distance of the artery to the medial sinus wall, diameter of the artery, and position of the artery were measured; presence of septa and pathology were recorded from CT sections. RESULTS Prevalence of sinus septa and sinus pathology was 16.1% and 24.8%, respectively. Artery was seen in 64.5% of all sinuses and was mostly intraosseous (68.2%). Mean diameter of PSAA was found 1.3 ± 0.5 mm. No significant correlation between the diameter of the artery and age was observed. CONCLUSIONS The results from this study suggested that CT scan is a valuable tool in evaluating presence of sinus pathology, septa, and arteries before maxillary sinus surgery. Although variations exist in every patient, the findings from this study suggest limiting the superior border of the lateral window up to 18 mm from the ridge to avoid any potential vascular damage.

The possible association among bone density values, resonance frequency measurements, tactile sense, and histomorphometric evaluations of dental implant osteotomy sites: a preliminary study.

Purpose:The aim of the clinical preliminary trial was to determine the possible relationship among radiologic bone density, primary implant stability, and tactile sense measurements, and to clarify their possible association with histological measurements at endosseous implant osteotomy sites. Materials:Eleven mandibular and 12 maxillary sites of 10 patients were included. Computerized tomography was used for preoperative evaluation of the jaw-bone for each dental implant site, and bone densities were recorded in Hounsfield units (HU). Implant stability quotients (ISQ) were determined with the Osstell Mentor device. Bone core biopsies were taken from the implant osteotomy sites, where the tactile sense of the practitioner while placing the implants was also recorded. Results:The average radiologic bone density, primary implant stability, and trabecular bone volume (TBV) values were 554.87 HU, 72 ISQ, and 41% for 23 dental implants, respectively. Maxillary sites presented a statistically significant decrease HU values compared with sites in the mandible. The mean TBV in mandibles presented a trend of increase compared to maxillary sites. A significant correlation was noted between ISQ values and tactile sense for male patients, where HU values demonstrated significant correlations among ISQ values, TBV measurements, and tactile sense evaluations in women. Conclusions:The results of this study demonstrated that computerized tomography measurements in terms of HU evaluations may be a helpful technique for predicting primary stability of the implant and bone quality. Further studies should be performed to understand the relationship between clinical assessments and histological evaluations in implant osteotomy sites in humans.

Clinical study on the insertion torque and wireless resonance frequency analysis in the assessment of torque capacity and stability of self-tapping dental implants

Resonance frequency (RF) analysis is a non-invasive, objective and sensitive technique developed for implantology where it measures the stability of the implant in osteotomy site. Although many studies were performed by the previous electronic version of RF analyzer, a very limited number of studies were carried out with the new magnetic wireless version. The aim of the study was to evaluate the relation between insertion torques, primary and secondary stability of self-tapping tapered implant systems. Thirteen subjects were treated with 42 endosseous implants using two-stage surgical procedure. The maximal insertion torque values were recorded prior to RF analysis during surgery. Six months after surgery, the secondary stability values were measured by the RF analysis. The average maximal insertion torque and primary and secondary magnetic RF values were 33 +/- 11 N cm and 66 +/- 12 ISQ and 71.9 +/- 6 ISQ for 42 implants respectively. The correlation between insertion torque and RF values were indicated to be statistically significant (P < 0.01). Significantly higher maximal insertion torque, and primary and secondary magnetic RF values were achieved in mandibular sites compared with maxillary areas (P < 0.01). No significant differences were measured for all parameters when both systems were compared with each other (P > 0.05). There was a strong correlation between the insertion torque, primary and secondary magnetic RF values of self-tapping tapered endosseous implant used. Further studies are needed to understand the impact of the wireless magnetic RF analysis technique in clinics.

Evaluation of Maxillary Incisive Canal Characteristics Related to Dental Implant Treatment With Computerized Tomography: A Clinical Multicenter Study

BACKGROUND A close anatomic relationship between the incisive canal and the roots of the central maxillary incisors should be kept in mind during dental-implant treatment in the anterior maxilla. The aim of the present study is to analyze incisive canal characteristics on computed tomography (CT) sections and to evaluate its relation to bone anterior to the canal with regard to dental implantation. METHODS A total of 933 partially edentulous and/or edentulous patients scheduled for implant insertion in four dental clinics enrolled in the present study. The following were measured and recorded from CT sections for analysis: 1) diameter and length of the incisive canal; 2) width and length of the bone anterior to the canal; 3) palatal bone width and length; and 4) root width and length of the central incisor. RESULTS Mean canal length was 10.86 ± 2.67 mm, and mean diameter was 2.59 ± 0.91 mm. Canal length was shortened in edentulous anterior maxilla compared to dentate maxilla. However, canal diameter did not show any difference between dentate and edentulous groups. Males had a longer and wider incisive canal than females. Canal shape was mostly cylindrical in 40.73% of images. No correlation was found with mean canal length and mean canal diameter according to age. CONCLUSIONS Although variations exist in every patient, the findings from this study suggest that sex and dental status are important factors that can affect incisive canal characteristics and amount of bone anterior to the canal. Clinicians should perform careful planning using CT scans before performing dental implant surgeries in premaxillary region.

Relationship between dental implant stability determined by resonance frequency analysis measurements and peri‐implant vertical defects: an in vitro study

Resonance frequency (RF) analysis is a non-invasive and objective technique developed for implantology, where it measures the stability of the implant in the bone socket. A limited number of studies were performed to compare different stability measurement devices. The aim of the study was to evaluate the association between the implant stability and peri-implant vertical defect by using the new wireless RF analyser. Micro-textured rough-surfaced implants with diameters of 3.7 and 4.8 mm and with a length of 12 mm were used. The peak insertion torque was recorded with the help of the torque control system only during the implant placement. The peri-implant defects were created in millimetre increments ranging between 0 and 5 mm to the same extent on all implants. The RF analysis values were measured by using the RF analyser. Significant correlation was found between insertion torque (44.3 +/- 3 N cm) and implant stability quotient (ISQ) (all implants: r = 0.76, 3.7 mm diameter: r = 0.65, 4.8 mm diameter: r = 0.80). For 3.7 x 12-mm(2) implants, the mean ISQ values were 72.6 +/- 2.4, 69.8 +/- 2, 67.2 +/- 1.8, 64.3 +/- 1.9, 61.2 +/- 2 and 57.2 +/- 2.5 when peri-implant vertical defects were 0, 1, 2, 3, 4 and 5 mm; and the corresponding values were 76.5 +/- 2.2, 74.5 +/- 2.2, 72.3 +/- 2, 70 +/- 1.9, 67 +/- 1.9 and 63.4 +/- 2.3, respectively, for 4.8 x 12-mm(2) implants. All values were significantly different when compared with each other. The wireless RF analyser seems to be a suitable and reliable device to determine the implant stability. Peri-implant bone loss simulated by using acrylic models may result with a decrease in ISQ values for osseo-integrated implants measured by the RF analyser.

Are Gingival Phenotype, Residual Ridge Height, and Membrane Thickness Critical for the Perforation of Maxillary Sinus?

BACKGROUND Sinus membrane perforation is the most common complication of the sinus-augmentation procedure. Anatomic factors have been implicated in the risk of sinus membrane perforation (SMP) during sinus-lift surgery. However, there are no reports on the relationships among gingival phenotype (GP), residual ridge height (RRH), membrane thickness (MT), and perforation rate of the maxillary sinus. Therefore, the aim of this clinical study is to determine the associations among GP, RRH, MT, and SMP rate. METHODS Forty-four patients (64 sinus-lift procedures) were included in the study. Preoperative computed tomography scanning was performed to radiographically evaluate GP, RRH, and MT. The smallest RRH, highest MT, and gingival thickness values were recorded. These values were classified as follows: RRH, < or >3.5 mm; MT, < or >1 mm; and GP, <1.5 or >2 mm. Sinus-lift surgery was performed with a lateral window approach, and SMPs were detected at 11 sinus sites. Perforation size and locations were recorded, and the perforations were repaired with collagen membrane. One hundred seventy-six implants were placed immediately after augmentation procedure. RESULTS Strong correlations of GP with RRH (r = 0.722, P = 0.001) and MT (r = 0.702, P = 0.001) were noted. Moderate correlations were found between RRH and MT (r = 0.596, P = 0.001) and between MT and SMP (r = 0.417, P = 0.001). Furthermore, mild correlations of SMP with RRH (r = 0.290, P = 0.020) and GP (r = 0.248, P = 0.04) were established. Four implants were lost, but no significant difference was found between implant failure and SMP. CONCLUSION Within the limits of the study, it may be suggested that GP, RRH, and MT may be important factors for sinus perforation.

Seven-Year Follow-Up Results of TiUnite Implants Supporting Mandibular Overdentures: Early versus Delayed Loading

BACKGROUND AND PURPOSE Implant-supported mandibular overdentures have recently become a popular treatment alternative for edentulous patients desiring increased retention of complete dentures. The goal of this study was to evaluate and present treatment outcomes of mandibular overdentures retained by two unsplinted, early-loaded implants and compare these results with those for delayed-loaded implants. MATERIAL AND METHODS Twenty-six edentulous patients had two interforaminal implants placed with a one-stage protocol. The patients were each treated with a mandibular overdenture supported by ball abutments. In the test group, the overdenture was loaded 1 week after surgery and in the control group, the overdenture was loaded 3 months after surgery. Standardized clinical and radiographic parameters were recorded at surgery, and after 3, 6, 12, and 18 months, and 2, 3, 4, 5, and 7 years. RESULTS Because two patients did not make the 7-year recall, only 24 patients (48 implants) were evaluated in this study. No implants were lost, and 1.31 ± 0.2 mm marginal bone resorption was noted for all implants after 7 years. Implant stability measurements, clinical peri-implant parameters and marginal bone levels exhibited no statistically significant differences between the two groups over 7 years. CONCLUSION The results of this clinical trial show that there is no significant difference in the clinical and radiographic outcomes of patients treated with mandibular overdentures supported by TiUnite implants that are either early or delayed loaded.

Vertical and horizontal dimensional evaluation of free gingival grafts in the anterior mandible: a case report series

The shrinkage of free gingival grafts (FGGs) is a well-known clinical phenomenon but there are limited studies demonstrating the dimensional changes during healing in FGGs. The aim of the study is to examine the shrinkage of FGG in both horizontal and vertical dimensions and calculate the changes in the surface area of the graft at early and delayed periods of healing. The FGG procedure was applied to 15 consecutive patients in their mandibular anterior area. The graft sizes and areas were measured and the shrinkage of the graft was calculated at baseline and days 10, 21 and 180. Hemorrhage, sense alteration and pain symptoms were also examined. Change in the horizontal direction was not statistically significant during the whole study period (p > 0.05). However, there was a statistically significant reduction in the vertical direction in all visits, except day 10 (p < 0.05). Calculated graft area was also significantly reduced during the study period at all time-points compared to the baseline (p < 0.001). At day 10, 4 (26.7%) recipient sites and 5 (33%) donor sites demonstrated paresthesia. Only one (0.07%) recipient site demonstrated paresthesia at day 21 where the donor site resulted with an uneventful healing. At day 10, 5 (33%) patients demonstrated bleeding at their donor regions and resulted with a complete cessation of bleeding at day 21. Pain symptom was found in 8 (53.3%) recipient sites where 3 (20%) donor regions presented pain symptom at day 10. Graft shrinkage in the vertical dimension seems to affect the clinical outcomes of the FGG procedure. However, the influence of horizontal graft shrinkage was minimal.

Relationships between implant stability, image‐based measures and nitric oxide levels

For monitoring of dental implants, practitioners seem to use simultaneously a variety of image-based and laboratory measurements. This longitudinal study was conducted to analyse the possible relationships between nitric oxide (NO) content of peri-implant sulcus fluid (PISF), marginal bone levels and implant stability in terms of resonance frequency analysis (RFA) at immediately (IL) and conventionally (CL) loaded mandibular molar dental implants from the same individuals. Dental implants were placed in 10 patients who had first molar loss bilaterally in the mandibular area. One site of the patient was determined as IL and the other site was CL. PISF samples, marginal bone level and RFA were taken for all dental implants during a 12-month follow-up period. For both types of loading, there were no significant changes at implant stability (ISQ) and PISF volume during the whole study period. The lowest total nitrite levels were observed at the end of 12 months. Marginal bone gain of 0.22 and 0.09 mm was noticed between 6 and 12 months in IL and CL groups, respectively. During the study period, negative correlation was noted between radiographic bone level and ISQ at both IL and CL sites; however, this correlation reached a significant level only at 6 months in CL implant group (P = 0.015). Although not significant, marginal bone loss seems to have a negative relationship with the implant stability values regardless of the mode of loading. NO metabolism around IL and CL dental implants may not demonstrate a significantly different pattern.