• Journal of Periodontal and Implant Science
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• 제46권5호
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• pp.337-349
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• 2016

Purpose: The aim of this study was to compare and analyze the peri-implant tissue conditions and prospective clinical outcomes associated with 2 types of hydroxyapatite (HA)-coated implants: (1) fully HA-coated implants and (2) partially HA-coated implants with resorbable blast medium on the coronal portion of the threads. Methods: Forty-four partially edentulous patients were randomly assigned to undergo the placement of 62 HA-coated implants, and were classified as the control group (partially HA-coated, n=30) and the test group (fully HA-coated, n=32). All patients had chronic periodontitis with moderate crestal bone loss around the edentulous area. The stability and clinical outcomes of the implants were evaluated using the primary and secondary implant stability quotient (ISQ), as well as radiographic, mobility, and peri-implant soft tissue assessments around the implants. The Wilcoxon signed-rank test and the Mann-Whitney test were used to evaluate differences between and within the 2 groups, with P values <0.05 considered to indicate statistical significance. Results: The fully HA-coated implants displayed good retention of crestal bone, and insignificant differences were found in annual marginal bone loss between the 2 types of HA-coated implants (P>0.05). No significant differences were found in the survival rate (group I, 100%; group II, 100%) or the success rate (group I, 93.3%; group II, 93.8%). The fully HA-coated implants also did not significantly increase the risk of peri-implantitis (P>0.05). Conclusions: The fully HA-coated implants did not lead to an increased risk of peri-implantitis and showed good retention of the crestal bone, as well as good survival and success rates. Our study suggests that fully HA-coated implants could become a reliable treatment alternative for edentulous posterior sites and are capable of providing good retention of the crestal bone.

• 대한치과보철학회지
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• 제45권2호
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• pp.274-282
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• 2007

Statement of problem: Main consideration was given to the stresses at the site of implant entry into the cortical bone at the alveolar crest. As a suspectible factor affecting the occurrence of stress concentrations, the contact angle between the implant and the alveolar crest bone was addressed. Purpose: The purpose of this study is to evaluate angles between the alveolar crest bone and the implant effect on the implant crestal area induced stresses using a finite element method. Material and methods: Cylindrically shaped, standard size ITI implants entering into alveolar crest with four different contact angles of 0, 15, 30, and 45 deg. with the long axis of the implant were axisymmetrically modelled. Alterations of stresses around the implants were computed and compared at the cervical cortical bone. Results and conclusion: The results demonstrated that regardless of the difference of the implant/alveolar crest bone contact angles, stress concentration occurred at the cervical bone and the angle differences led to insignificant variations in stress level.

• 구강회복응용과학지
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• 제33권1호
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• pp.47-54
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• 2017

상악 구치부는 치조제 골 흡수와 상악동 함기화로 인해 가용골의 양은 제한되고 골질도 좋지 않은 경우가 대부분으로 상악동저의 거상 후 가용골의 증대와 취약한 골에서 임플란트의 견고한 초기 고정을 획득하는 것이 중요하다. 심하게 위축된 치조제의 경우 임플란트의 적절한 초기 고정 획득을 위해 측방접근법을 통한 상악동 골이식술이나 지연 임플란트 식립법이 추천되나 본 연구에서는 수직적 잔존골 높이가 3 mm 이하인 상악 구치부 세 증례를 통해 수직 골 소실이 심한 상악 구치부에서 전통적인 개념과는 달리 최소침습적 수술법으로 치조정 접근을 통한 상악동 골이식과 동시에 임플란트 식립을 시행하여 합병증 없이 충분한 길이의 임플란트 식립이 가능함을 제안한다.

• Journal of Periodontal and Implant Science
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• 제34권1호
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• pp.127-138
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• 2004

Background: Crestal bone loss known as saucerization is a frequently observed phenomenon. Recent studies have shown that implants with micothreaded crest module reduced the force concentration in the crestal region thus resulting in no or reduced crestal bone loss. This study presents a clinical, histologic, and histometric evaluation of implants with microthreaded crest module and SLA surface. Methods: The implants were placed in the mandible of 5 beagle dogs weighing 10-15kg. Four premolars were bilaterally extracted 8 weeks prior to implant placement. Mucoperiosteal flap was elevated and drilling with increasing diameter was performed under saline irrigation. After countersinking 2 implants were placed in each side resulting in 4 implants per dog. Healing period of 8 weeks was allowed before sacrificing the animals. Histologic preparation was performed for histologic and histometric analysis. Bone to implant contact as well as percentage of bone area inside threads were measured. T-test was used for statistical analysis with pvalue p<0.05. Results: 1. Healing was uneventful without any cover screw exposure. New bone formation around the implants was observed without any inflammatory infiltration. 2. Bone to implant contact in the microthread and thread were 43.90 ${\pm}$ 20.30 %, and 53.19 ${\pm}$ 20.97 % respectively. The overall bone to implant contact was 48.54 ${\pm}$ 20.95 %. 3. Percentage of bone area inside threads were 54.43 ${\pm}$ 10.39 %, and 38.44 ${\pm}$ 16.44 % for the microthread and thread respectively. There was statistically significant difference(p<0.05). The overall percentage of bone area inside threads was 46.67 ${\pm}$ 15.68 %.

• 구강회복응용과학지
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• 제20권1호
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• pp.57-70
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• 2004

The significance of occlusion has regained its popularity in dentistry with the introduction of implant therapy. Literature has reported that the clinical success and longevity of dental implants can be achieved by biomechanically controlled occlusion. Occlusal overload is known to be one of the main causes for implant failure. Evidences have suggested that occlusal overload contribute to early implant bone loss as well as deosseointegration of successfully integrated implants. Unlike natural teeth, osseointegrated implants are ankylosed to surrounding bone without the periodontal ligament (PDL) which provides mechanoreceptors as well as shock-absorbing function. Moreover, the crestal bone around dental implants may act as a fulcrum point for lever action when a force (bending moment) is applied, indicating that implants/implant prosthesis could be more susceptible to crestal bone loss by applying force. Hence, it is essential for clinicians to understand inherent differences between teeth and implants and how force, either normal or excessive force, may influence on implants under occlusal loading. The purposes of this paper are to review the importance of implant occlusion, to establish the optimum implant occlusion with biomechanical rationale, to provide clinical guidelines of implant occlusion and to discuss how to manage complications related to implant occlusion.

• 대한치과보철학회지
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• 제39권3호
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• pp.273-281
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• 2001

Digital subtraction radiography may be one of the most precise and noninvasive methods for assessing subtle density changes in peri-implant bone, providing additional diagnostic information on implant tissue integration in overall maintenance. The aims of this study were to evaluate density changes after first, second surgery of dental implant and to measure the amount of marginal bone loss 9 months after second surgery using digital subtraction radiography. Bone change around 30 screw-shaped implants in 16 patients were assessed on radiographs. 17 Branemark implants of 3.75mm in diameter(Nobel Biocare, Goteborg, Sweden), 2 Branemark implants of 5.0mm in diameter, 11 $Replace^{TM}$ implants of 4.3mm in diameter(Nobel Biocare, Goteborg, Sweden) were used. To standardize the projection geometry of serial radiographs of implants, customized bite block was fabricated using XCP film holder(Rinn Corporation, Elgin, IL.) with polyether impression material of Impregum(ESPE, Germany) and direct digital image was obtained. Qualitative and quantitative changes on radiographs were measured with Emago software(The Oral Diagnostic System, Amsterdam, Netherlands). The results were as follows: 1. The peri-implant bone density of 69.2% implants did not change and the peri-implant bone density of 30.8% implants decreased after 3 months following first surgery. 2. The crestal bone density of 53.9% implants decreased first 3 months after second surgery. The crestal bone density of 58.8% implants increased 9 months after second surgery. No density change was observed around the midportion of the implants after second surgery, 3. The amount of marginal bone loss between different kinds of implants showed no statistically significant differences (p>0.05). 4. More than 90% of total marginal bone loss recorded in a 9-month period occurred during the first 3 months.

• Journal of Periodontal and Implant Science
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• 제43권4호
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• pp.153-159
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• 2013

Purpose: The level of the implant above the marginal bone and flap design have an effect on the bone resorption during the healing period. The aim of this study is to detect the relationship between the level of the implant at the implant placement and the bone level at the healing period in the mesial and distal side of implants placed with flapless (FL) and full-thickness flap (FT) methods. Methods: Twenty-two nonsubmerged implants were placed with the FL and FT technique. Periapical radiographs were taken of the patient at implant placement, and at 6 and 12 weeks. By using computer software, bone level measurements were taken from the shoulder of the healing cap to the first bone implant contact in the mesial and distal side of the implant surface. Results: At 6 weeks, the correlation between the crestal bone level at the implant placement and crestal bone level of the FT mesially was significant (Pearson correlation coefficient=0.675, P<0.023). At 12 weeks, in the FT mesially, the correlation was nonsignificant (Spearman correlation coefficient=0.297, P<0.346). At 6 weeks in the FT distally, the correlation was nonsignificant (Pearson correlation coefficient=0.512, P<0.107). At 12 weeks in the FT distally, the correlation was significant (Spearman correlation coefficient=0.730, P<0.011). At 6 weeks in the FL mesially, the correlation was nonsignificant (Spearman correlation coefficient=0.083, P<0.809). At 12 weeks in the FL mesially, the correlation was nonsignificant (Spearman correlation coefficient= 0.062, P<0.856). At 6 weeks in the FL distally, the correlation was nonsignificant (Spearman correlation coefficient=0.197, P<0.562). At 12 weeks in the FL distally, the correlation was significant (Pearson correlation coefficient=0.692, P<0.018). Conclusions: A larger sample size is recommended to verify the conclusions in this preliminary study. The bone level during the healing period in the FT was more positively correlated with the implant level at implant placement than in the FL.

• 대한심미치과학회지
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• 제28권1호
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• pp.27-41
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• 2019

예지성 있는 대구치부 임플란트을 위해서는 Crestal bone Stabliity를 위해 임플란트 주위에 biologic width라 할 수 있는 적절한 두께의 연조직이 필요하다. 그러기 위해선 기존에 우리가 적절하다고 혹은 어쩔 수 없는 한계라고 생각했던 깊이보다 좀 더 치조골 하방으로 깊이 심어야 하는 경우가 많은 것 같다. 이번 투고에서는 case report와 함께 관련된 surgical technique에 대해서 소개하면서 구치부 임플란트의 수직적 위치에 대해서 생각보고자 한다.

• 대한치과교정학회지
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• 제48권6호
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• pp.367-376
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• 2018

Objective: This study was performed to investigate the changes in alveolar bone after maxillary incisor intrusion and to determine the related factors in deep-bite patients. Methods: Fifty maxillary central incisors of 25 patients were evaluated retrospectively. The maxillary incisors in Group I (12 patients; mean age, $16.51{\pm}1.32years$) were intruded with a base-arch, while those in Group II (13 patients; mean age, $17.47{\pm}2.71years$) were intruded with miniscrews. Changes in the alveolar envelope were assessed using pre-intrusion and post-intrusion cone-beam computed tomography images. Labial, palatal, and total bone thicknesses were evaluated at the crestal (3 mm), midroot (6 mm), and apical (9 mm) levels. Buccal and palatal alveolar crestal height, buccal bone height, and the prevalence of dehiscence were evaluated. Two-way repeated measure ANOVA was used to determine the significance of the changes. Pearson's correlation coefficient analysis was performed to assess the relationship between dental and alveolar bone measurement changes. Results: Upper incisor inclination and intrusion changes were significantly greater in Group II than in Group I. With treatment, the alveolar bone thickness at the labial bone thickness (LBT, 3 and 6 mm) decreased significantly in Group II (p < 0.001) as compared to Group I. The LBT change at 3 mm was strongly and positively correlated with the amount of upper incisor intrusion (r = 0.539; p = 0.005). Conclusions: Change in the labial inclination and the amount of intrusion should be considered during upper incisor intrusion, as these factors increase the risk of alveolar bone loss.

• 대한치과보철학회지
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• 제45권2호
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• pp.263-273
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• 2007

Statement of problem: Alteration of tooth function is assumed to be changed by stress/strain on the adjacent alveolar bone, producing changes in morphology similar to those described for other load-bearing bones. When teeth are removed, opposing teeth will not be functioned. When edentulous area is restored by implant prostheses, opposing teeth will be received physiologic mechanical stimuli. Purpose: The aim of this study was to evaluate the bone changes around the teeth opposing implant restoration installed mandibular posterior area. Material and method: Eight patients who had mandibular posterior edentulous area were treated with implants. Radiographs of the opposing teeth were taken at implant prostheses delivery(baseline), 3 months, and 6 months later. Customized film holding device was fabricated to standardize the projection geometry for serial radiographs of opposing teeth. Direct digital image was obtained. Gray values of region of interest at each digital image were measured and compared according to time lapse. Repeated measured analysis of variance and post-hoc Scheffe's test were performed at the 95% significance level. Results: Alveolar bone changes around the natural teeth opposing the posterior implant in mandible showed statistically significant difference compared to control group(P<0.05). And gray values of alveolar bone around the teeth opposing implants were increased. There were no statistically significant differences of alveolar bone changes between crestal group and middle group and between mesial group and distal group according to time lapse(P>0.05). There were no statistically significant differences of alveolar bone changes among mesial-crestal group, mesial-middle group, distal-crestal group, distal-middle group, and control group(P>0.05). Conclusion: Alveolar bone around the natural teeth opposing the implant prosthesis showed gradual bony apposition.