Su Gwan Kim

A comparative study of two noninvasive techniques to evaluate implant stability: Periotest and Osstell Mentor

OBJECTIVESnThe purpose of this study was to examine the usefulness of Periotest and Osstell Mentor (a resonance frequency analysis) as nondestructive analytical tools for determining implant stability in clinics, to evaluate the precision of both instruments, and to determine the applicability of these measured values as clinically relevant indices.nnnSTUDY DESIGNnFour adult mongrel dogs weighing about 12 to 15 kg were used in this study. Bilateral extractions of the first through the fourth mandibular and maxillary premolars were performed and a total of 48 commercially pure titanium screw implants (USII Plus; OSTEM Implant, Seoul, Republic of Korea) were placed at 4 weeks after extraction. All implants (10 mm length and 3.3 mm diameter) were self-tapping and surface-treated with resorbable blast media (RBM). Periotest values (PTVs) obtained from Periotest, and Implant Stability Quotient (ISQ) obtained from Osstell Mentor, were measured at the time of implantation, and 3 and 6 weeks after implantation. At 3 and 6 weeks after implantation, 4 dogs were humanely killed and histomorphometric analysis was performed. The new peri-implant bone formation rate (NBFR) was measured.nnnRESULTSnThe PTV value was lower and ISQ value was higher at 6 weeks when compared with data collected at 3 weeks after implantation. The PTVs of the maxilla were higher than the mandible and the ISQ values of the maxilla were lower than the mandible. Based on the NBFR, the 6-week group showed higher bone formation when compared to the 3-week group, correlating to the observed PTV and ISQ values. Additionally, the NBFR was higher in the maxilla than the mandible. No significant difference between PTV and ISQ was also observed when PTV and ISQ were compared to NBFR.nnnCONCLUSIONnThe results indicated that the Periotest and Osstell Mentor, both noninvasive diagnostic devices, were useful and comparably reliable, showing a strong association with each other in assessing implant stability.

Evaluation of sinus bone resorption and marginal bone loss after sinus bone grafting and implant placement

OBJECTIVEnThe objective of this study was to evaluate the sinus bone graft resorption and marginal bone loss around the implants when allograft and xenograft are used.nnnSTUDY DESIGNnSinus bone grafting and implant placement (Osstem, Korea) were performed on 28 patients from September 2003 to January 2006. In group I, a total of 49 implants were placed in 23 maxillary sinus areas of 16 patients together with bone graft using xenograft (Bio-Oss) and a minimal amount of autogenous bone. In group II, 24 implants were placed in 13 maxillary sinus areas of 12 patients together with bone graft using a minimal amount of autogenous bone and equal amounts of allograft (Regenaform) and Bio-Oss in group II.nnnRESULTSnEarly osseointegration failures of 3 implants in 3 patients (group I: 1 patient, 1 implant; group II: 2 patients, 2 implants) were observed, and revisions were performed for these 3 implant sites, followed by complete prosthodontic treatments. The average height of the remaining alveolar bone before the surgery, immediately after the surgery, and 1 year after the surgery was 4.9 mm, 19.0 mm, and 17.2 mm, respectively, in group I. In group II, the average height of the remaining alveolar bone was 4.0 mm, 19.2 mm, and 17.8 mm before the surgery, immediately after the surgery, and 1 year after the surgery, respectively. The average marginal bone loss 1 year after prosthodontic loading and after 20.8 months follow-up was 0.6 mm and 0.7 mm, respectively, in group I. A 93.9% success rate was observed for group I, with 3 implants showing bone resorption of >1.5 mm within 1 year of loading. For group II, the average marginal bone loss 1 year after prosthodontic loading and after 19.7 months follow-up was 0.7 mm and 1.0 mm, respectively. An 83.3% success rate was observed for group II, with 4 implants showing bone resorption of >1.5 mm within 1 year of loading.nnnCONCLUSIONSnBased on the observations in this study, it was concluded that mixed grafting with demineralized bone matrix for maxillary sinus bone grafting has no significant short-term merit regarding bone healing and stability of implants compared with anorganic bovine bone alone.

Hydroxyapatite/polylactide biphasic combination scaffold loaded with dexamethasone for bone regeneration.

This study presents a novel design of a ceramic/polymer biphasic combination scaffold that mimics natural bone structures and is used as a bone graft substitute. To mimic the natural bone structures, the outside cortical-like shells were composed of porous hydroxyapatite (HA) with a hollow interior using a polymeric template-coating technique; the inner trabecular-like core consisted of porous poly(D,L-lactic acid) (PLA) that was loaded with dexamethasone (DEX) and was directly produced using a particle leaching/gas forming technique to create the inner diameter of the HA scaffold. It was observed that the HA and PLA parts of the fabricated HA/PLA biphasic scaffold contained open and interconnected pore structures, and the boundary between both parts was tightly connected without any gaps. It was found that the structure of the combination scaffold was analogous to that of natural bone based on micro-computed tomography analysis. Additionally, the dense, uniform apatite layer was formed on the surface of the HA/PLA biphasic scaffold through a biomimetic process, and DEX was successfully released from the PLA of the biphasic scaffold over a 1-month period. This release caused human embryonic palatal mesenchyme cells to proliferate, differentiate, produce ECM, and form tissue in vitro. Therefore, it was concluded that this functionally graded scaffold is similar to natural bone and represents a potential bone-substitute material.

Osteogenic activity of the mixture of chitosan and particulate dentin

To evaluate the healing effect of a mixture of chitosan and particulate dentin, a 8-mm-diameter critical size defect was created in the calvarium of 75 rats. The rats were divided into four experimental groups and a control group (no treatment). The defects in the experimental groups were grafted either with pig particulate dentin (group 1), a mixture of particulate dentin and plaster of Paris (group 2), particulate dentin and chitosan (group 3), or chitosan only (group 4). Rats in each group were sacrificed 2, 4, and 8 weeks after implantation. All experimental groups showed more new bone formation when compared to the control group. Additionally, all groups exhibited more bone growth at 8 weeks than at 4 weeks after implantation. It was concluded from this study that defects treated with particulate dentin powder-chitosan mixture may mediate an excellent effect on the formation of new bones.

A short-term study on immediate functional loading and immediate nonfunctional loading implant in dogs : Histomorphometric evaluation of bone reaction

OBJECTIVESnThe purpose of this study was to evaluate implant stability after short-term immediate loading in a canine model.nnnSTUDY DESIGNnThe control group used in this study was immediate nonfunctional loading and the experimental group was immediate functional loading. Each group was measured for its periotest value (PTV) and bone-to-implant contact (BIC) ratio.nnnRESULTSnStatistically significant differences in PTV and BIC ratio were not observed between the control and the experimental groups.nnnCONCLUSIONnIt was concluded that implant stability can be achieved even with immediate loading.

Evaluation of peri-implant tissue in nonsubmerged dental implants: a multicenter retrospective study

OBJECTIVESnThe objective of this study was to evaluate the peri-implants hard and soft tissue response associated with the 1-stage, nonsubmerged, endosseous dental implant.nnnSTUDY DESIGNnA multicenter retrospective clinical evaluation was performed on 339 nonsubmerged implants placed in 108 patients at 5 clinical centers between January 2003 and December 2007.nnnRESULTSnAfter a mean follow-up period of 30 months, the mean crestal bone resorption in 339 implants was 0.43 mm. The survival and success rates were observed to be 99.1% and 95.1%, respectively. The mean calculus, inflammatory, and plaque indices were 0.13, 0.37, and 0.73, respectively, and the mean width of buccal keratinized mucosa was observed to be 2.43 mm.nnnCONCLUSIONnThe short- to intermediate-term evaluation of the 1-stage, nonsubmerged, endosseous implant yields relatively high survival and success rates.

Prognosis and evaluation of tooth damage caused by implant fixtures

Damage to adjacent teeth is one of the various complications that may occur during implant placement and is often the result of improper direction during fixture placement or excessive depth of placement. In general, if detrimental symptoms, such as reaction to percussion in damaged teeth, mobility, and pulp necrosis, are not present, osseointegration should be observed at follow-up. In three cases, the possibility of root damage due to an implant fixture placed too close to each adjacent tooth was perceived on radiographs. However, in all of these cases, there were no clinical symptoms or radiographic changes present in the tooth, and the implants did not exhibit decreased stability or peri-implantitis. Therefore, we can carefully predict that the implant fixture close to the adjacent tooth did not invade the cementum of the root, and therefore did not produce the suspected pulpal damage or periradicular symptoms. In this study, we considered both the implant status as well as the adjacent tooth.

The treatment of malocclusion after open reduction of maxillofacial fracture: a report of three cases

The posttraumatic complications of jaw fractures related to jaw function and facial deformity include nonunion, malunion, malocclusion, temporomandibular joint dysfunction and facial asymmetry. This report presents cases referred to our department for revision of malunion and malocclusion following inadequate reduction of jaw fractures. Three patients with posttraumatic malocclusions caused by malunion were treated with a LeFort I osteotomy in one case and re-fracture in two cases. All of the patients exhibited stable results without further complications (e.g., malunion or malocclusion). Accurate preoperative diagnosis and proper anatomical reduction of the fracture segments are essential to preventing post-surgical malunion and malocclusion.

Guided bone regeneration using demineralized allogenic bone matrix with calcium sulfate: case series

PURPOSE The purpose of this case series was to evaluate the effect of guided bone regeneration using demineralized allogenic bone matrix with calcium sulfate. MATERIALS AND METHODS Guided bone regeneration using Demineralized Allogenic Bone Matrix with Calcium Sulfate (AlloMatrix™, Wright. USA) was performed at the time of implant placement from February 2010 to April 2010. At the time of the second surgery, clinical evaluation of bone healing and histologic evaluation were performed. The study included 10 patients, and 23 implants were placed. The extent of bony defects around implants was determined by measuring the horizontal and vertical bone defects using a periodontal probe from the mesial, distal, buccal, and lingual sides and calculating the mean and standard deviation of these measurements. Wedge-shaped tissue samples were obtained from 3 patients and histologic examination was performed. RESULTS In clinical evaluation, it was observed that horizontal bone defects were completely healed with new bones, and in the vertical bone defect area, 15.1% of the original defect area remained. In 3 patients, histological tests were performed, and 16.7-41.7% new bone formation was confirmed. Bone graft materials slowly underwent resorption over time. CONCLUSION AlloMatrix™ is an allograft material that can be readily manipulated. It does not require the use of barrier membranes, and good bone regeneration can be achieved with time.

Prognosis of closure of large sinus membrane perforations using pedicled buccal fat pads and a resorbable collagen membrane: case series study.

For large membrane perforations that develop during sinus-bone grafting, we performed repairs using a pedicled buccal fat pad and a resorbable collagen membrane simultaneously with the bone graft. This study included eight patients. Postoperative maxillary sinusitis developed in two patients, which we managed with incision and drainage, and antibiotics. Ultimately, six patients received 12 implants, three of which failed (75% success). Implant replacement was performed after the removal of the failed replacement, at which point the prosthetic treatment was considered complete. In all of the six cases that we were able to follow-up with, the sinus-bone graft was healing favorably. We observed that the sinus bone height decreased gradually with time. Based on these case series, we conclude that our procedure of repairing large sinus-membrane perforations with a pedicled buccal fat pad and a collagen membrane is a reliable technique.