Jung Kiu Chai

Periodontal wound healing/regeneration following implantation of recombinant human growth/differentiation factor-5 (rhGDF-5) in an absorbable collagen sponge carrier into one-wall intrabony defects in dogs: A dose-range study

AIMnRecombinant human growth/differentiation factor-5 (rhGDF-5) is being evaluated as a candidate therapy in support of periodontal regeneration. The objective of this study was to evaluate cementum and alveolar bone formation, and aberrant healing events following surgical implantation of rhGDF-5 in an absorbable collagen sponge (ACS) carrier using an established periodontal defect model.nnnMATERIALS AND METHODSnBilateral 4 x 5 mm (width x depth), one-wall, critical-size, intrabony periodontal defects were surgically created at the mandibular second and fourth pre-molar teeth in 15 Beagle dogs. Five animals received 1 microg/defect and five animals 20 microg/defect rhGDF-5 in unilateral defect sites. Contralateral sites received treatments reported elsewhere. Five animals received rhGDF-5/ACS with 0 (buffer control) and 100 microg/defect rhGDF-5 in contralateral defect sites. The animals were euthanized at 8 weeks post-surgery for histologic and histometric evaluation.nnnRESULTSnSurgical implantation of rhGDF-5 stimulated significant periodontal regeneration. Cementum formation was significantly enhanced in sites implanted with rhGDF-5 (1 and 100 microg) compared with control (p<0.05). Similarly, bone formation height was significantly greater in sites receiving rhGDF-5 (1 and 100 microg) compared with control (p<0.05). There were no significant or remarkable differences in bone and cementum formation within the selected dose interval (1, 20 and 100 microg rhGDF-5). None of the control or the rhGDF-5 sites exhibited root resorption, ankylosis, or other aberrant tissue reactions.nnnCONCLUSIONnSurgical implantation of rhGDF-5/ACS may be used safely to support periodontal wound healing/regeneration in intrabony periodontal defects without complications.

Long-term retrospective study of narrow implants for fixed dental prostheses.

OBJECTIVEnThe objectives of this study were to analyze retrospectively the long-term survival and success rates of Narrow implants (NIs) placed with various implant systems, and the association with biological and technical complications.nnnMATERIAL AND METHODSnIn total, 338 patients (menxa0=xa045.6%, womenxa0=xa054.4%) who received 541 NIs (≤3.5xa0mm in diameter) for fixed prostheses were enrolled in this retrospective study. The mean marginal bone level (MMBL) change was calculated. Life table analysis with the cumulative survival rate and success rate was calculated, and biological and technical complications were evaluated.nnnRESULTSnThe annual MMBL change was 0.07xa0±xa00.20xa0mm. The 12-year cumulative survival (success) rates of NIs were 98.1% (91.8%) and 98.5% (93.8%) for the implant- and subject-based analysis, respectively. During the observation period up to 12xa0years (mean 4.9xa0years), six implants were lost in the maxilla, whereas three implants were lost in the mandible. Technical complications were more frequent than biological complications. Infection was the most common underlying cause of biological complications and the most frequent technical complication was decementation.nnnCONCLUSIONnIn conclusion, the findings of this study suggest that NIs could be used safely for narrow alveolar ridges or narrow mesiodistal spaces on the basis of their high survival rate.

Flap extension attained by vertical and periosteal-releasing incisions: a prospective cohort study.

OBJECTIVESnTo evaluate the effect of vertical and periosteal-releasing incisions (PRI) on the extension of the buccal flap in a trapezoidal flap design.nnnMATERIAL AND METHODSnThirty patients scheduled for implant surgery accompanied by bone augmentation were recruited. The amount of flap extension pulled with a minimal tension of 5 g using a dynamometer was measured before and after the first and the second vertical incisions (VI) and PRI. The results were compared based on gender, surgical site and operators experience.nnnRESULTSnThe first VI extended flap length by 1.1 ± 0.6 mm, 113.4% more compared with the original flap length. The second VI increased flap length by 1.9 ± 1 mm (124.2%), and the PRI significantly extended flap length by 5.5 ± 1.5 mm (171.3%) (P<0.001). The length of the first and the second VI and the amount of flap extension by each incision were compared, and there were no statistically significant differences between gender, surgical site (maxilla vs. mandible) and operators experience (faculty vs. residents).nnnCONCLUSIONnVertical and PRI in a trapezoidal flap design can be successfully utilized to attain tension-free primary closure during implant or periodontal surgeries. However, the PRI appears to be the only determinant key factor that can significantly extend the length of the flaps, while host- and operator-related factors might not have any significant effect on such flap extension.

Prevalence and Anatomic Topography of Mandibular Tori: Computed Tomographic Analysis

PURPOSEnMandibular tori are located above the mylohyoid ridge. These features are relatively common in most populations, but their prevalence varies with race. The purpose of this study was to identify the prevalence and features of mandibular tori in a Korean population using computed tomographic (CT) images.nnnMATERIALS AND METHODSnThe CT images of 726 patients were analyzed in this study. The presence or absence of a mandibular torus was identified on the CT images of each patients quadrants and categorized according to gender and age. The most common location was also evaluated according to the corresponding teeth. The cortical thickness of each torus was evaluated using a 3-dimensional reconstruction software program.nnnRESULTSnThe prevalence of mandibular tori in the entire sample was 24.1%, and most cases were bilateral. Mandibular tori were observed more frequently in young adults, with the prevalence being inversely related to age. The most frequently observed location was the premolar region, and the mean cortical thickness was 6.9 mm.nnnCONCLUSIONSnMandibular tori seem to change with aging. The prevalence in the present sample composed of Koreans was 24.1%, and younger patients may be more likely to develop a mandibular torus. Most tori presented a medium size bilaterally in the lingual aspect of the premolar region, and all were composed of cortical bone.

Comparison of collagen membrane and bone substitute as a carrier for rhBMP-2 in lateral onlay graft

OBJECTIVESnTo evaluate the bone regenerative effect of bioresorbable collagen membrane (CM) as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) when performing lateral onlay grafts using bovine hydroxyapatite incorporated with collagen matrix (BHC) in combination with CM in dogs.nnnMATERIAL AND METHODSnA guided bone regeneration (GBR) was performed at the buccal aspect of edentulous maxillary alveolar ridges in dogs (n = 5): (1) BHC group, in which rhBMP-2-loaded BHC was covered by a CM, and (2) CM group, in which BHC was covered by an rhBMP-2-loaded CM. A histologic and histometric analysis was performed after 8 weeks of healing.nnnRESULTSnBoth the BHC and CM groups exhibited substantial newly formed bone (NB). More NB was found in the CM group than in the BHC group without statistical significance. Most of the NB was in direct contact with the residual bone substitute in the BHC group, whereas the projections and islands of NB were observed in the spaces between the residual bone substitute clusters in the CM group. The bone-to-residual bone substitute contact ratio was significantly lower in the CM group than in the BHC group (P = 0.043).nnnCONCLUSIONSnWithin the limitations of this study, it can be concluded that rhBMP-2-loaded CM performed lateral onlay grafts as effectively as rhBMP-2-loaded BHC while showing less bone-residual bone substitute contact ratio in dogs. The loading of CMs with rhBMP-2 might therefore be a recommendable treatment option for facilitating lateral onlay graft combined with rhBMP-2.

The Effects of Autograft and Calcium Carbonate on the Periodontal Healing of 3-Wall Intrabony Defects in Dogs

This study evaluated periodontal repair and biomaterial reaction following implantation of a calcium carbonate and autogenous bone on the regeneration of 3-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group I was treated with a calcium carbonate and the experimental group II was treated with autograft. The subjects were sacrificed 8 weeks after surgery and a comparative histometric analysis was done. No root resorption or ankylosis were observed in the experimental group. ANOVA post Hoc test showed that the experimental group II produced statistically significant higher gain in connective tissue adhesion, new cementum regeneration and new bone formation. These results suggest that the use of autograft in 3-wall intrabony defects has a significant effect on new cementum and new bone formation height.

The Effect of Calcium Sulfate with Alloplast on the Periodontal Regeneration in One-Wall Intrabony Defect of Beagle Dogs

Calcium sulfate used in this study is newly fabricated to overcome its disadvantages; brittleness, difficult handling properties, rapid resorption and reaction heating. Especially when calcium sulfate is used in the graft procedure, it is difficult to control the setting time, solubility into blood and body fluid. To improve the handling properties, Calcium sulfate is mixed with Carboxylmethylcellulose (CMS). The putty type calcium sulfate used in the present study presented lower values in cementum formation and new bone formation than the control group. This may be due to use of poor osteoinductive calcium sulfate alone in the defect, limiting new bone formation. In addition, complete resorption of calcium sulfate after 8 weeks presents that addition of polymer failed to delay the resorption rate of calcium sulfate. Rather, it seemed to disturb the natural healing of the defect when compared with the findings in the control group. But the favorable result of calcium sulfate is shown when used with alloplast. The material used in the present study was developed for easier formability and manipulation avoiding scattering or dissolving of the material with blood or body fluid. However, the results reveal that further studies on effect of calcium sulfate with various other bone graft materials and ideal ratios in mixing the two should be determined in the future.However, the results reveal that further studies on effect of calcium sulfate with various other bone graft materials and ideal ratios in mixing the two should be determined in the future.

Effects of Mixture of Fibrin-Fibronectin Sealant System and Calcium Carbonate in Periodontal Intrabony Defects

This study evaluated the effects of mixture of fibrin-fibronectin sealant system(FFSS) and calcium carbonate(CC) in periodontal intrabony defects. Thirty six sites with two or three wall intrabony defect were used. 14 defects treated with periodontal flap surgery were assigned as the control group. 11 defects treated with CC implantation were designed as experimental group 1 and 11 defects, treated with CC and FFSS implantation as experimental group 2. The control and experimental groups all achieved statistically significant improvements in probing depth and clinical attachment level from the baseline (P<0.01). In mean postsurgery probing depth and gingival recession reduction, there were no statiscally significant differences between the experimental groups and the controls. However, mean postsurgery clinical attachment levels of both experimental groups improved significantly more than that of the controls. As a result, we suggest that mixture of FFSS and CC can be used effectively in intrabony defect as osteoconductive materials.