• Imaging Science in Dentistry
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• v.49 no.4
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• pp.265-272
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• 2019

Purpose: To compare the diagnostic accuracy of cone-beam computed tomography (CBCT) with that of parallel(PPA) and oblique projected periapical(OPA) radiography for the detection of different types of peri-implant bone defects. Materials and Methods: Forty implants inserted into bovine rib blocks were used. Thirty had standardized bone defects(10 each of angular, fenestration, and dehiscence defects), and 10 were defect-free controls. CBCT, PPA, and OPA images of the samples were acquired. The images were evaluated twice by each of 2 blinded observers regarding the presence or absence and the type of the defects. The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were determined for each radiographic technique. The 3 modalities were compared using the Fisher exact and chi-square tests, with P<0.05 considered as statistical significance. Results: High inter-examiner reliability was observed for the 3 techniques. Angular defects were detected with high sensitivity and specificity by all 3 modalities. CBCT and OPA showed similar AUC and sensitivity in the detection of fenestration defects. In the identification of dehiscence defects, CBCT showed the highest sensitivity, followed by OPA and PPA, respectively. CBCT and OPA had a significantly greater ability than PPA to detect fenestration and dehiscence defects(P<0.05). Conclusion: The application of OPA radiography in addition to routine PPA imaging as a radiographic follow-up method for dental implantation greatly enhances the visualization of fenestration and dehiscence defects. CBCT properly depicted all defect types studied, but it involves a relatively high dose of radiation and cost.

• Journal of Periodontal and Implant Science
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• v.45 no.6
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• pp.229-237
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• 2015

Purpose: The aim of this study was to determine the clinical feasibility of using dehydrothermally cross-linked collagen membrane (DCM) for bone regeneration around peri-implant dehiscence defects, and compare it with non-cross-linked native collagen membrane (NCM). Methods: Dehiscence defects were investigated in twenty-eight patients. Defect width and height were measured by periodontal probe immediately following implant placement (baseline) and 16 weeks afterward. Membrane manipulation and maintenance were clinically assessed by means of the visual analogue scale score at baseline. Changes in horizontal thickness at 1 mm, 2 mm, and 3 mm below the top of the implant platform and the average bone density were assessed by cone-beam computed tomography at 16 weeks. Degradation of membrane was histologically observed in the soft tissue around the implant prior to re-entry surgery. Results: Five defect sites (two sites in the NCM group and three sites in the DCM group) showed soft-tissue dehiscence defects and membrane exposure during the early healing period, but there were no symptoms or signs of severe complications during the experimental postoperative period. Significant clinical and radiological improvements were found in all parameters with both types of collagen membrane. Partially resorbed membrane leaflets were only observed histologically in the DCM group. Conclusions: These findings suggest that, compared with NCM, DCM has a similar clinical expediency and possesses more stable maintenance properties. Therefore, it could be used effectively in guided bone regeneration around dehiscence-type defects.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.5
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• pp.361-366
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• 2020

Guided bone regeneration (GBR) is a surgical procedure that utilizes bone grafts with barrier membranes to reconstruct small defects around dental implants. This procedure is commonly deployed on dehiscence or fenestration defects ≥2 mm, and mixing with autogenous bone is recommended on larger defects. Tension-free primary closure is a critical factor to prevent wound dehiscence, which is critical cause of GBR failure. A barrier membrane should be rigidly fixed without mobility. If the barrier is exposed, closed monitoring should be utilized to prevent secondary infection.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.182-192
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• 2018

Purpose: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. Methods: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). Results: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks ($4.80{\pm}1.31$ and 4.3 mm in group Z1_D, and $4.47{\pm}1.06$ and $4.5{\pm}1.37mm$ in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points ($34.15%{\pm}21.23%$ at 2 weeks, $84.08%{\pm}1.33%$ at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. Conclusions: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.286-298
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• 1999

The endodontic-periodontic combined lesions have been difficult to get correct diagnosis and predictable treatment. This study was to make the experimental endodontic-periodontic combined defects in dogs for the study of the periodontal regeneration and to evaluate the efficacy of the enamel matrix protein and e-PTFE membrane in the experimental endodontic-periodontic combined defects. 5 mongrel dogs were used. The pulp chambers were opened and the plaque was inserted into the chambers to induce the periapical lesions on the mandibular second, third and fourth premolars of the dogs. 1 month later, the root canal treatments were done with gutta perch a and ZOE sealer. On the day of surgery, the periapical defects were standardized by trephine bur. The buccal dehiscence defects were made by the dental bur and bone chisels. The apicoectomy with retrofilling was done. The prepared roots were randomly selected for test and control groups. In the experimental groups, the enamel matrix derivative and e-PTFE membrane were used. Nothing was placed on the control group. Fluroscent labelling was used to evaluate the bone formation. After 4 and 12 weeks, the dogs were sacrificed and undecalcified sections were prepared and stained with toluidine blue. Those histologic sections were examined by fluorescent microscopy and light microscopy. The results were as follows. 1. In the control group, new bone was formed in the periapical defects and scarcely in the buccal dehiscence defects. New cementum was not detected at 4 and 12 weeks. 2. In the experimental groups, new bone, new cementum and periodontal ligament were found in the periapical and buccal dehiscence defects. The relative amount and the quality of the new bone, new cementum and periodontal ligament tissue that had formed on the experimental groups were superior to those of the control group. 3. The current observation implicated that e-PTFE membrane and enamel matrix protein could be the effective tools for the guided tissue regeneration of the endo-perio combined defects.

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.301-320
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• 1995

The purpose of this study was to evaluate a new biodegradable membrane - atelocollagen as a guided tissue regeneration barrier on the dehiscence defects adjacent to the dental implants. 3 beagle dogs were selected for this study and all the mandibular premolars($P_1,P_2,P_3&P_4$) were extracted. Twelve weeks after the extraction, the edentulous ridges were formed to be placed the titanium plasma-sprayed IMZ implants. Four implant osteotomies were performed on each side of the mandible. The osteotomies were placed facially in the edentulous ridges to approximate an actual dehiscence defect as closely as possible, The standardized dehiscence defects were created 3 mm in width and 4 mm in height by osteotomy. A total 24 implants were placed. e-PTFE, ateloco11agen and $Collatape^{(R)}$ were placed to cover the defects and the one defect served as a control, not covered any membrane. By random selection, three dogs were sacrificed at 2 weeks, 4weeks and 8 weeks after fixation with 3% glutaraldehyde. A week before sacrificing, 8-week dog was infused intravenously with oxy-tetracycline 30mg/kg. The left mandibular blocks were used for full decalcified histologic preparation and the right mandibular blocks were selected for undeca1cified preparation, At 2 weeks, the regenerated bone of e-PTFE and atelocollagen groups appeared to be more dense than other groups and the percentage of bone defect fill was highest for e-PTFE and follwed by ateloco1lagen group. However, the $Collatape^{(R)}$ and control groups showed a little new bone formation. $Collatape^{(R)}$ was almost degraded within 2 weeks. At 4 weeks, the regenerated new bone were much greater and denser than at 2 weeks for e-PTFE and ateloco11agen group. Although a part of atelocollagen bagan to be degraded at the margin and surrounded by foreign body giant cells related to foreign body reaction, it was generally intact and the regenerated new bone was shown much more than at 2 weeks. The amount of new bone in $Collatape^{(R)}$ and control groups at 4 weeks were similar to that of 2 weeks group. At 8 weeks, the regenerated bone was matured and observed along the implant fixture. Direct new bone formation and calcium deposits beneath the e-PTFE were observed. No further bone growth was seen in the $Collatape^{(R)}$ and control groups. In reflected fluoromicrcocopic observation, the osteogenic activity was pronounced between e-PTFE membrane and the old bone. High osteogenic activity was also observed in atelocol1agen group. This study suggested that the ateloco11agen as well as e-PTFE could be used for guided tissue regeneration on dehiscence defects adjacent to the dental implants. But the $Collatape^{(R)}$ was completely resorbed within 2 weeks and was not a suitable membrane for guided bone regeneration.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.191-198
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• 2008

Purpose: Guided bone regeneration(GBR) has emerged as a treatment in the management of osseous defects associated with dental implants. But several studies have reported different degrees of success of guided bone regeneration, depending upon the type of barrier selected, presence or absence of an underlying graft material, types of graft material, feasibility of technique, and clinician's preference. The aim of the present study was to evaluate bone formation following dental implant placement with augmentation materials at dehiscence defects in dogs. Material and Methods: Standardized buccal dehiscence defects($3{\times}5\;mm$) were surgically 2 Mongrel dog's mandibles, each 8 SLA surface, 8 anodizing surface implants. Each buccal dehiscence defect received flap surgery only(no treatment, control), $Cytoflex^{(R)}$ membrane only, Resolut $XT^{(R)}$ membrane only, Resolut $XT^{(R)}+Osteon^{TM}$. Animals were sacrificed at 8 weeks postsurgery and block sections were harvested for histologic analysis. Resuts: All experimental group resulted in higher bone formation than control. Resolut $XT^{(R)}+Osteon^{TM}$ group resulted appeared highest defect resolution. There was no difference between SLA and anodizing surface, nonresorbable and resorbable membrane. Conclusion: GBR results in rapid and clinically relevant bone closure on dehiscence defects of the dental implants.

• Journal of Periodontal and Implant Science
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• v.27 no.2
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• pp.347-361
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• 1997

The present study investigates the effects of DFDB graft combined with Calcium sulfate membrane on the periodontal wound healing in dehiscence defects of dogs. Following the initiation of general anesthesia by I.V. administration of 30mg/kg of pentobarbital, first premolar was extracted and full-thickness flap was elevated from the second to the fourth premolar. The portion of premolars coronal to the alveolar crest was removed and mesial and distal roots separated to produce single rooted teeth. Exposed root canals were sealed with Caviton and covered completely with flaps sutured. Following the healing period of 12 weeks, the surgical sites were uncovered and $4{\times}4mm$ dehiscence defects were surgically created. Those defects with DFDB graft combined with Calcium sulfate membrane following root planing, were designated as test sites and those with flap surgery-only were designated as controls. 1. No foreign-body reaction or inflammation were observed in either groups. Calcium sulfate was completely resorbed in the test sites. 2. Significantly greater amounts of new cementum was observed in test sites compared with the controls. Significant amounts of functionally orientated collagens were observed in the test sites. 3. New bone formation was observed in significantly greater amounts in test sites. The results suggest that combined graft of DFDB and calcium sulfate is extremely biocompatible with a potential for new bone and cementum formation, and functional alignment of periodontal ligaments.

• Journal of Periodontal and Implant Science
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• v.26 no.4
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• pp.799-821
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• 1996

The ultimate goal of periodontal treatment has been to facilitate regeneration of diseased periodontal tissues, destroyed by inflammatory periodontal disease. For regeneration of the periodontium to occur, all of component tissues must be restored to their original position and architecture. Growth factors which were known to promote the cellular processes, ie, proliferation, migration and matrix synthesis, have been in the spotlight of current periodontics. Platelet-derived growth factor(PDGF) stimulates collagen and non collagen protein synthesis, migration and proliferation of periodontal ligament cells. Insulin-like growth factor(IGF) has potentials to induce collagen and bone matrix synthesis so that it regulates normal bone remodeling. Application of the combination have been known to facilitate formation of bone and cementum, and to synergistically interact to promote coronal migration and proliferation of periodontal ligament cells. These two growth factors have been reported to exhibit positive effect in the periodontally diseased teeth or class m furcation defects. The aim of the present study was to test the hypothesis that PDGF-BB alone or the combination of PDGF-BB and IGF-I can predictably enhance regeneration of the periodontium in the dehiscence defect. Following the resection of premolars, roots were embedded. After 12 weeks of healing period, standardized experimental $4{\times}4mm$ dehiscence defects were created on the mid-facial of the premolar roots in each of 4 young adult dogs. In control group, only methylcellulose gel was inserted in the defects. In experimental group I and II, gel with $2{\mu}g$ of PDGF-BB or $2{\mu}g$ of PDGF-BB and $1{\mu}g$ of IGF-I was inserted in the defects, respectively. At 8 weeks postsurgery, the dogs were sacrificed. The results were observed histologically and analyzed histomorphometrically.The results of this study were as follws. 1. The new cementum formation was $1.26{\pm}0.69mm$ in the control group, $1.80{\pm}0.84mm$ in the experimental group I, $1.93{\pm}0.51mm$ in the experimental group II. The experimental group III, the experimental group I, the control group were in the order of cementum formation without statistically significant differences between control and all experimental groups. 2. The new bone formation was $1.00{\pm}0.53mm$ in the control group, $1.53{\pm}0.63mm$ in the experimental group I, $l.33{\pm}0.45mm$ in the experimental group II. The experimental group I, the experimental group II, the control group were in the order of bone formation without statistically significant differences between control and all experimental groups. 3. The root resorption was $1.12{\pm}0.64mm$ in the control group, $1.34{\pm}0.73mm$ in the experimental group I, $0.79{\pm}0.59mm$ in the experimental group II without statistically significant differences between control and all experimental groups. These results suggested that the use of PDGF-BB alone or PDGF-BB and IGF-I in the dehiscence defects might facilitate periodontal regeneration in some degree, but has not shown statistically significant results.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.687-702
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• 2005

The purpose of this study is to examine the effect of non-resorbable membrane such as e-PTFE which was used with DFDB in bone regeneration on dehiscence defect in peri-implant area. Amomg the patients, who have recieved an implant surgery at the department of Periodontics in Dan Kook University Dental Hospital, 12 patients showed implant exposure due to the dehiscence defect and 15 implants of these 22 patients were the target of the treatment. Periodontists randomly applied $Gore-Tex^{(R)}$ to the patients and treated them with antibiotics for five days both preoperatively and postoperatively. Reentry period was 26 weeks on average in maxilla and 14 weeks on average in mandible. The results were as follows : 1. Dehiscence bone defect frequently appeared in premolar in mandible and anterior teeth in maxilla respectively. 2. Among 15 cases, 1 membrane exposure was observed and in this case, regenerated area was decreased. 3. In non-resorbable membrane, bone surface area $9.25{\pm}4.84$ preoperatively and significantly increased to $11.48{\pm}7.52$ postoperatively(0.05). 4. The increase of bone surface area in non-resorbable membrane was $2.23{\pm}3.38$. 5. As a result of histopathological finding, DFDB surrounded by new bone formation and lamellate bone, resorption of DFDB and bone mineralization was found. Also, fibrosis of connective tissue beneath the membrane was found. This study shows that the surgical method using DFDB and non-resorbable membrane on dehiscence defect in peri-implant area is effective in bone regeneration.