Seung-Beom Kye

Immediate implant placement into infected and noninfected extraction sockets: a pilot study

OBJECTIVE This study compared the osseointegration of immediate implants in dogs in infection-free sites and in sites with periradicular lesions which were removed by simulated periradicular surgery. STUDY DESIGN Periradicular surgeries were performed to remove intentionally induced periradicular lesions, followed by teeth extraction and immediate implant placement with (experimental group 1) or without (experimental group 2) membranes. In the control group, implants were placed at healthy extraction sockets. After 12 weeks, the animals were killed and the results of histomorphometric study were analyzed by Kruskal-Wallis test. RESULTS Both the control and the experimental implants were clinically acceptable. The control group showed significantly higher bone-implant contact (BIC; 76.03 +/- 7.98%) than the experimental groups 1 (59.55 +/- 14.21%) and 2 (48.62 +/- 20.22%) (P < .05). CONCLUSIONS Despite the lower BIC of the experimental groups, this pilot study showed the possibility that immediate implant placement might be successful in extraction sockets with periradicular lesions. Further studies with larger sample sizes are required.

Relationship between implant stability measured by resonance frequency analysis (RFA) and bone loss during early healing period

OBJECTIVE The aim of this study was to monitor the changes in the stability-related bone loss during the early healing period. STUDY DESIGN A total of 43 implants were installed in 19 patients, and their stability was measured by resonance frequency analysis (RFA) at the time of surgery and once per week for 12 weeks. A total of 32 implants had radiographs taken at the placement of implant and 4, 8, and 12 weeks postoperatively. The data for gender, bone density, different surgery protocols, and bone loss around implant were analyzed. RESULTS The mean implant stability quotient values were not changed during the healing period. The marginal bone losses at 12 weeks were 1.28 +/- 0.51 mm and 1.32 +/- 0.57 mm on the mesial and distal sides, respectively. CONCLUSIONS The implant stability in normal and hard bone density did not change with time, and there was no correlation between the marginal bone loss and the change of implant stability.

Human gingival fibroblast (HGF-1) attachment and proliferation on several abutment materials with various colors.

PURPOSE An implant abutment should be soft tissue-compatible and resistant to plaque accumulation, and it is preferable for an implant abutment to have color harmony with the surrounding tissues. This study aimed to compare the in vitro fibroblast cell attachment and proliferation on several abutment materials of different colors. MATERIALS AND METHODS A total of 240 specimens in 6 experimental groups were used: titanium alloy (SM [smooth machined]; gray), cobalt-chrome-molybdenum alloy (CCM; gray), titanium nitride-coated titanium (TiN; yellow), anodic-oxidized titanium (AO; dark pink), composite resin-coated titanium (R; white), and zirconia (Zr; white). The culture plate surface was employed as a control (C). The surface roughness (Sa), developed interfacial area ratio (Sdr), and water contact angle (WCA) were measured. The human gingival fibroblast (HGF-1) attachment and proliferation at the third and seventh days were observed. RESULTS Sa values of all experimental groups were < 0.5 μm. Sdr values were between 5% and 8%, except for the Zr group (0.06%). WCA of all groups was greater than 40 degrees. More HGF-1 cells attached on the surfaces of the SM, TiN, and Zr groups than the C group, and the least number of cells were observed on the CCM group (P < .001). On the third day of proliferation, the C group showed significantly greater proliferation than all experimental groups (P < .001). On the seventh day of proliferation, the TiN, AO, Zr, and C groups exhibited twice the number of cells compared to the rest of the groups (P < .001). CONCLUSION Within the limitations of this study, zirconia abutments would be the best choice in the anterior region. Titanium nitride-coated titanium alloy abutments or anodic-oxidized titanium alloy abutments might also be good choices in areas of esthetic challenge or under high occlusal loads.

Computed tomographic assessment of maxillary sinus wall thickness in edentulous patients

Posterior maxillary region is considered to be the most challenging area for dental implant placement. Lateral window opening is the gold standard procedure for maxillary sinus augmentation in this area. The purpose of this study is to evaluate lateral wall thickness of the maxillary sinus for sinus augmentation using computed tomography (CT) in edentulous patients. Computed tomography images of 302 patients were analysed. Using the maxillary sinus floor as the reference point in edentulous regions, lateral wall thickness was measured on CT scans. After drawing a tangent line at the lowest point of the sinus floor, another perpendicular line to the tangent line was drawn at the same point of the sinus floor. Thickness of the lateral wall of the maxillary sinus was measured using 10DR implant software at 3 (R1), 10 (R2) and 15 mm (R3) from the sinus floor. The mean thickness of the lateral wall of the maxillary sinus from the first premolar to second molar was 1·69 ± 0·71, 1·50 ± 0·72, 1·77 ± 0·78 and 1·89 ± 0·85 mm, respectively. The thickness differed significantly at the R2 and R3 points. Women had thinner lateral walls at the R1 and R2 points at the premolars than did men. At the R2 and R3 points at the second premolar, the mean thickness of smokers was larger than that of non-smokers. There were no significant differences on age or reasons for tooth loss. The changes in the thickness of the lateral wall at different reference points were observed, and CT examinations may help make lateral window without membrane perforation.

The effect of non‐resorbable membrane on buccal bone healing at an immediate implant site: an experimental study in dogs

OBJECTIVE For successful implant treatment in the esthetic area, stable hard tissue and soft tissue are very important. At the buccal side without buccal bone defects, prophylactic guided bone regeneration (GBR) with bone substitute was frequently used for achieving thick buccal bone. The aim of this study was to evaluate the effect of GBR using a non-resorbable membrane in an immediate implant site without bone defects. MATERIAL AND METHODS Immediate implants were placed into the mandibles of four mongrel dogs. In the experimental group (TM group), a non-resorbable membrane was placed and fixed onto the buccal bone plate around the implant. In the control group, the implants were placed without membrane coverage. After 12 weeks, the dogs were sacrificed and histological specimens were prepared. The vertical distances from the smooth-rough surface interface (SRI) to the gingiva, the first-bone contact, and the bone crest were measured on the buccal and lingual sides. The horizontal thicknesses of the gingiva and bone at 0, 1, 2, and 3 mm below the SRI were measured. RESULTS In the TM group, first-bone contact on the buccal side was more coronally positioned approximately 0.8 mm than the control group (P=0.041). The buccal bone thickness of the TM group was well preserved and there was no difference between the buccal and lingual sides. Comparing the control group, implants of the TM group had 1 mm thicker buccal bone (P=0.0051 at bone 1 mm level, P=0.002 at bone 2 mm level). In the control group, buccal bone loss was observed and buccal bone was about 1 mm thinner than the lingual bone (P<0.05). CONCLUSIONS GBR with a non-resorbable membrane and no bone graft substitute could help to preserve buccal bone thickness on the immediate implant site without defects.

Effect of implant drill design on the particle size of the bone collected during osteotomy

The bone particles collected during osteotomy could be used as autogenous bone graft materials for implant placement surgery. This study examined the effect of drill design on the quantity and size of bone collected during the preparation of implant sites. Bone was collected during the in vitro preparation of bovine bone using three different implant system drills: parallel shape (Group 1), tapered shape (Group 2), and tapered and stepped shape (Group 3). Bone particles were sieved. The wet volume and dry weight were measured. The mean total wet volume collected per osteotomy was 0.199±0.0445ml and the dry weight was 0.0477±0.0087g. In all three groups, bone particles >500μm were harvested in larger amounts than particles 250-500 and <250μm. Group 3 drills produced smaller bone particles than Group 1 and 2 drills. The size differences were significant when Group 3 particles were compared with the particles produced by Group 1 drills. The differences in total dry weight of bone collected by the three drilling systems were not statistically significant. Drill design significantly influenced the size of bone particles collected during the preparation of implant sites.

Location of maxillary intraosseous vascular anastomosis based on the tooth position and height of the residual alveolar bone: computed tomographic analysis

Purpose The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. Methods Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,<4 mm; group 2, between 4 and 8 mm; and group 3, >8 mm. Results The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. Conclusions Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation. Graphical Abstract

The Effects of Defect Type and Depth, and Measurement Direction on the Implant Stability Quotient Value.

The purpose of this study was to evaluate the effect of defect type and depth as well as measurement direction on implant stability in an ex vivo peri-implant bovine rib bone model. Six kinds of defects (3-wall 2.5 mm, 3-wall 5 mm, 1-wall 2.5 mm, 1-wall 5 mm, circumferential 2.5 mm, circumferential 5 mm), and control (no defect) were prepared in 14 bovine rib bones. A total of 84 defects and 14 controls were created. The same type and size of implants (4 × 10 mm) were placed in each group. The thickness of cortical bone and the insertion torque were measured for each defect, and the implant stability quotient (ISQ) value was measured 3 times from 4 different directions. The thickness of cortical bone ranged from 2.71-3.18 mm. Insertion torque decreased as the defect size increased. As the defect size for the same defect depth increased, the ISQ value decreased (P < .001). There were significant differences between the ISQ values obtained with different measurement directions only between the control and 3-wall 5 mm defect (P < .0001). The ISQ value opposite to the defect direction was higher than that in the defect direction in all 3 directions of the 3-wall and 1-wall 5 mm defects. ISQ values were influenced by defect type and depth. Loss of cortical bone reduced the stability of implants and reduced the ISQ value. Measurement direction also influenced ISQ values.