• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.48-55
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• 2020

Purpose: The purpose of this study was to utilize cone-beam computed tomography (CBCT) image analysis to obtain anatomical information related to the morphology of the incisive foramen to provide useful data regarding implant placement and clinical procedures such as anesthesia. Methods: The study included 167 patients who underwent CBCT scans over 20 years. Three components were measured: 1) the anteroposterior and mediolateral diameter of the incisive foramen, 2) the horizontal bone thickness anterior to the incisive foramen, and 3) the vertical bone height coronal to the incisive foramen. All measurements were expressed as mean±standard deviation and were analyzed by a single examiner. Results: The anteroposterior diameter of the incisive foramen was wider than the mediolateral diameter (P<0.001). The diameter of the incisive foramen in patients in whom the central incisors were present was smaller than that in those in whom at least one central incisor was absent, but no statistically significant difference between the groups was observed. The horizontal bone thickness in the patients with central incisors was statistically significantly larger than that in the patients without at least one central incisor (P<0.001). The same pattern was observed with regard to vertical height, but that difference was not statistically significant. Conclusions: The buccal bone thickness anterior to the incisive foramen was significantly decreased after central incisor loss. It is necessary to identify the morphology of the bone and the location of the incisive foramen via CBCT to avoid invasion of the incisive foramen and nasopalatine canal.

• Imaging Science in Dentistry
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• v.51 no.3
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• pp.243-250
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• 2021

Purpose: The objective of this study was to evaluate the amount of height available for a maxillary sinus augmentation procedure without blocking the ostium and jeopardizing the drainage of the ostiomeatal complex using cone-beam computed tomography (CBCT) imaging. Materials and Methods: A total of 200 sinonasal complexes comprising 100 dentate and 100 edentulous scans were retrospectively assessed using CBCT. Invivo 5.0, a CBCT reconstruction program, was used for image evaluation. The coronal section demonstrating the ostiomeatal complex was selected as a reference view to perform measurements of the sinus. The measurements were done by 2 evaluators in separate sessions. Comparative analyses of measurements were performed between dentate and edentulous patients and between male and female patients. Results: The safe height to which the sinus can be elevated without compromising the integrity of the ostiomeatal complex was calculated for each sinus. In the presence of significant mucosal thickening, the height available for augmentation was calculated by subtracting the height of mucosal thickening from the sinus floor to the location of the ostium. In this study, the available height was approximately 27.05 mm for dentate and 23.40 mm for edentulous patients. The inter-operator reliability was excellent for all the parameters evaluated. Conclusion: This retrospective study with a limited number of patients from a single university-based site shows that CBCT is valuable in evaluating the location and patency of the ostium for planning sinus augmentation procedures for dental implant placement.

• Journal of Periodontal and Implant Science
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• v.49 no.4
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• pp.237-247
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• 2019

Purpose: To analyze the maxillary sinus anatomy over edentulous ridges in the bilateral posterior maxillary area in Taiwanese patients using cone-beam computed tomography (CBCT). Methods: In total, 101 anatomical sites from 61 patients, including 32 premolar and 69 molar regions, were analyzed using CBCT. Measurements were made of the width and height of edentulous ridges, the thickness of the lateral wall of the maxillary sinus, and the presence of a sinus septum and the posterior superior alveolar artery (PSAA). A statistical analysis of the measurements was performed, and correlations among the measurements were assessed. Results: The average ridge width was $10.26{\pm}3.16mm$, with a significantly greater ridge width in the second molar region than in the premolar region. The mean residual ridge height was $8.55{\pm}4.09mm$, and ridge height showed an opposite trend from ridge width for the premolar and molar regions. A sinus septum was present at 5.9% of the sites, and the PSAA was observed in 24.5%. The average thickness of the lateral wall of the maxillary sinus was $2.08{\pm}0.94mm$, with no significant difference between the tooth position and lateral wall thickness. Conclusions: This study presents the anatomical features of the maxillary sinus, which should be considered in sinus lift procedures for implant placement, in the Taiwanese population. The use of CBCT is recommended to avoid intraoperative complications.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.30 no.2
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• pp.102-111
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• 2021

Implant placement in the anterior region is performed in several stages, and harmonization of both hard and soft tissues is essential. In addition, adequate esthetic and functional evaluations are necessary in the process of transitioning from the provisional to the final prosthesis to attain patient satisfaction. Although gingiva can be molded in the anterior region, depression in the occlusal view can yield good results through the augmentation procedure. However, the harvesting of connective tissue from the palate is not suitable for various reasons, such as postoperative discomfort and intraoperative bleeding. Compared to the palatal area, the harvesting of connective tissue from the maxillary tuberosity can easily result in relatively thick tissue and quick healing of the donor site, thus proving to be a good modality for graft procedures. The purpose of this report is to examine the relevant evidence from previous studies and evaluate the process of soft tissue augmentation through a case presentation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.136-142
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• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.307-314
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• 2013

Purpose: The aim of this study was to evaluate the effect of immobilization of the recombinant human bone morphogenetic protein 2 (rhBMP-2) on anodized titaum implants coated with heparin to enhance the vertical alveolar ridge augmentation in the supraalveolar peri-implant defect region. Materials and methods: 18 pure titanium implants (7.0 mm in length, 3.5 mm in diameter) were manufactured for this study. All implants were anodized and designed insertion reference line marked with laser at the apical 2.5 mm from the fixture platform. Implantation of 6 noncoated anodized implants (Control group), 6 anodized implants physically adsorbed with rhBMP-2 by dip and dry method (BMP group) and 6 anodized implants chemically immobilized 3,4-dihydroxyphenylalanine (DOPA)-heparin/ rhBMP-2 (Hep-BMP group) was performed in the both mandibular of three male adult beagle dogs using split-mouth design. Radiologic examinations were performed immediately after implant placement and 4 and 8 weeks after implant placement. The amount of mesio-distal bone augmentation was evaluated by measuring the vertical distance from the platform to the marginal bone. Statistical analysis was performed using one-way analysis of variance (SPSS version 18.0) and multiple comparison analysis of The Kruskal-Wallis test and the Mann-Whitney U test. Statistical significance was established at the 5% significant level. Results: At the 4 weeks vertical alveolar ridge augmentation of Control group, BMP group and Hep-BMP group is $0.09{\pm}0.22mm$, $1.02{\pm}0.72mm$, and $1.29{\pm}0.51mm$, At the 8 weeks $0.11{\pm}1.26mm$, $1.11{\pm}0.58mm$, $1.59{\pm}0.79mm$ according to radiographic observations. The two experimental groups showed a significantly increasing in vertical bone height compared with the control group (P<.05). However, there is no significant difference between the BMP group and Hep-BMP group (P>.05). Conclusion: The rhBMP-2 coated implants were enhanced the vertical bone growth in the supraalveolar peri-implant defect area. However, there is no significant difference between chemically and physically coating method.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.283-305
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• 2001

The purpose of this study was to analyze the stress distribution of condylar regions and edentulous mandible with implant-supported cantilever prostheses on the certain conditions, such as amount of load, location of load, direction of load, fixation or non-fixation on the condylar regions. Three dimensional finite element analysis was used for this study. FEM model was created by using commercial software, ANSYS(Swanson, Inc., U.S.A.). Fixed model which was fixed on the condylar regions was modeled with 74323 elements and 15387 nodes and spring model which was sprung on the condylar regions was modeled with 75020 elements and 15887 nodes. Six Br${\aa}$nemark implants with 3.75 mm diameter and 13 mm length were incorporated in the models. The placement was 4.4 mm from the midline for the first implant; the other two in each quardrant were 6.5 mm apart. The stress distribution on each model through the designed mandible was evaluated under 500N vertical load, 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. The load points were at 0 mm, 10 mm, 20 mm along the cantilever prostheses from the center of the distal fixture. The results were as follows; 1. The stress distribution of condylar regions between two models showed conspicuous differences. Fixed model showed conspicuous stress concentration on the condylar regions than spring model under vertical load only. On the other hand, spring model showed conspicuous stress concentration on the condylar regions than fixed model under 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. 2. Fixed model showed stress concentration on the posterior and mesial side of working and balancing condylar necks but spring model showed stress concentration on the posterior and mesial side of working condylar neck and the posterior and lateral side of balancing condylar neck under vertical load. 3. Fixed model showed stress concentration on the posterior and lateral side of working condylar neck and the anterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior sides of working and balancing condylar necks under horizontal load linguobuccally. 4. Fixed model showed stress concentration on the posterior side of working condylar neck and the posterior and lateral side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 20 degree oblique load. 5. Fixed model showed stress concentration on the anterior and lateral side of working condylar neck and the posterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 45 degree oblique load.. 6. The stress distribution of bone around implants between two models revealed difference slightly. In general, magnitude of Von Mises stress was the greatest at the bone around the most distal implant and the progressive decrease more and more mesially. Under vertical load, the stress values were similar between implant neck and superstructure vertically, besides the greatest on the distal side horizontally. 7. Under horizontal load linguobuccally, buccal 20 degree oblique load and buccal 45 degree oblique load, the stress values were the greatest on the implant neck vertically, and great on the labial and lingual sides horizontally. After all, it was considered that spring model was an indispensable condition for the comprehension of the stress distributions of condylar regions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.6
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• pp.644-651
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• 2000

In cases of severe alveolar bony resorption in the edentulous posterior maxillae, implant placement is limited anatomically due to maxillary sinus. If the ridge is atrophic, the various bone grafting methods are required for the ridge augmentation. But the result of the onlay grafting procedure is not always promising. On the posterior maxilla, maxillary sinus mucosa lifting and bone grafting into the sinus floor, subantral augmentation(SA) technique are recommended. Various SA procedures have been developed for implant installation. We perfer to simultaneous block bone graft and implant installation through the residual alveolar ridge into the grafted block bone to fix the grafted bone and to gain the primary stability of the installed fixture. When a sagittal skeletal discrepancy in present due to the severe alveolar bony resorption of the maxilla, the advancement of the maxilla by Le Fort I osteotomy simultaneously with installation of implant fixtures combined with sinus lifting and interpositional bone graft procedure can be indicated. We applied various SA techniques for implant installtion to the 46 edentulous posterior maxillae, and total 154 implants were installed at our department from 1992 to 1999. Various SA techniques were classified in detail and the indications of each techniques were discussed. The changes of residual bony height following SA procedure were studied. The results were as follows. 1. The SA procedure combined with bone graft and simultaneous fixture installation were performed in 41 cases, 126 fixtures were installed and 5 fixtures were removed out of them. Le Fort I osteotomy procedure combined with sinus lifting and interpositional bone graft simultaneous with fixture installation were performed in 5 cases. Total 28 fixtures were installed and 2 fixtures were removed so far. 2. Autogenous block bone graft into sinus floor were performed in 35 cases, autogenous particulated marrow cancellous bone(PMCB) graft in 9 cases, and demineralized human bone powder in 2 cases. The donor site for bone graft were anterior iliac bone in 39 cases, posterior iliac bone in 3 cases and mandibular symphysis in 1 case and mandibular ramus in 1 case. 3. In 9 cases with which SA procedure had been performed with the block bone graft, the change of pre- and postoperative residual bony height were measured using MPR(multiplanar reformatted)-CT. The mean residual bony height was 8.0mm preoperatively, 20.2mm at 6 months following up operation and we gained average 12.2mm alveolar bony height. So, we can recommend this one-stage subantral augmentation and fixture installation technique as a time conserving, safe and useful method for compromised posterior edentulous maxilla.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.459-466
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• 2010

Alveolar distraction osteogenesis (ADO) has been regarded as an acceptable treatment for the alveolar bone deficiency. For ADO at anterior maxillary area, the vector should be oriented to forward and down-ward direction to get an adequate occlusion with mandibular teeth and to increase bone length and width for implant placement. However, the conventional commercial distraction devices for ADO are designed to allow mainly downward movement of alveolar segment, even though a forward movement can be obtained a little by controlling of inclination of device. To make ADO with controllable bidirectional vector possible, we used customized devices using self-manufactured ABDUL (Alveolar Bone Distractor Using Lag screw principle) and commercial orthodontic palatal expansion device ($Hyrex^{(R)}$). In all cases (n = 4), ADO could be performed successfully and dental implants were able to placed with adequate occlusion. We report the procedures, advantages and disadvantages of these methods.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.3
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• pp.226-229
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• 2006

The interforaminal region is usually considered as a safe region in the chin bone graft without important vital anatomical structures to be damaged. But the accurate anatomy of the interforaminal region, with its potential clinical relationships, is controversial. Moreover some complications suggesting damage of incisive terminal branches after chin bone harvesting are reported such as sensory discomfort and pain etc. In order to verify incisive innervation of symphyseal area, we examined the cross-sectional CT scan images taken for preoperative planning of implant placement with chin bone graft and some parameters were measured; (1) visuality rating of incisive canal (2) vertical and horizontal diameter of canal (3) distance from lower border of the incisive canal to the lower border of the mandible (4) shortest distance from anterior border of the incisive canal to the anterior border of the mandible. We report the positive outcome that decrease the complications related with the damages of incisive branch during bone harvesting from the chin.