• Imaging Science in Dentistry
• /
• v.33 no.1
• /
• pp.43-49
• /
• 2003

Purpose : To evaluate the differences in bone height, bone width, and visibility of posterior spiral tomographic images according to various exposure directions, image layer thickness, and inclination of the mandibular inferior border. Materials and Methods: Six partially and completely edentulous dry mandibles were radiographed using Scanora spiral tomography. Spiral tomography was performed at different exposure directions (dentotangential and maxillotangential projection), image layer thicknesses (2 mm, 4 mm and 8 mm), and at various inclinations to the mandibular border (+ 100, 00 and -10°). The bone height and width was measured using selected tomographic images. The visibility of mandibular canal, crestal bone, and buccal and lingual surfaces were graded as 0, 1, or 2. Results : The bone width at the maxillo-tangential projection was wider than at the dento-tangential projection (p < 0.05). The visibility of buccal and lingual surface at the maxillo-tangential projection was higher than at the dento-tangential projection (p<0.05). Thinner image layer thicknesses resulted in greater visibility of buccal and lingual surfaces (p < 0.05). Bone height was greatest in the -10° group, and at the same time the bone width of the same group was the narrowest (p < 0.05). The visibility of alveolar crest and buccal surface of the + 10° group was the highest, while the visibility of the mandibular canal was greatest in the 00 group. Conclusion: When spiral tomography is performed at the mandibular posterior portion for visualization prior to implant surgery, it is important that the inferior border of mandible be positioned as parallel as possible to the floor. A greater improvement of visibility can be achieved by maintaining a thin image layer thickness when performing spiral tomography.

• The Journal of Advanced Prosthodontics
• /
• v.16 no.1
• /
• pp.1-11
• /
• 2024

PURPOSE. The present experiment aimed to evaluate the placement accuracy of fully guided implant surgery using a mucosa-supported surgical guide when the protocol of osteotomy and installation was modified (MP) compared to when the protocol was sequentially and conventionally carried out (CP). MATERIALS AND METHODS. For 24 mandibular dentiform models, 12 dentists (6 experts and 6 beginners) performed fully guided implant placements two times at the right first and second molar sites using a mucosa-supported surgical guide, once by the CP (CP group) and at the other time by the MP (MP group). The presurgical and postsurgical stereolithographic images were superimposed, and the deviations between the virtually planned and actually placed implant positions and the procedure time were compared statistically (P < .05). RESULTS. The accuracies were similar in the CP and MP groups. In the CP group, the mean platform and apex deviations at the second molar site for the beginners were +0.75 mm and +1.14 mm, respectively, which were significantly larger than those for the experts (P < .05). In the MP group, only the mean vertical deviation at the second molar site for the beginners (+0.53 mm) was significantly larger than that for the experts (P < .05). The procedure time was significantly longer for the MP group (+94.0 sec) than for the CP group (P < .05). CONCLUSION. In fully guided implant surgery using a mucosa-supported guide, the MP may improve the placement accuracy when compared to the CP, especially at sites farther from the most-posterior natural tooth.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.33 no.1
• /
• pp.47-54
• /
• 2017

The atrophy of edentulous ridge and pneumatization of the maxillary sinus often limit the volume of bone available for implant placement on maxillary posterior teeth. Most clinicians suffer difficulties from poor bone quality and quantity on maxillary posterior site. Thus, the success of maxillary posterior implant surgery depends on the increase of the available bone and obtaining a good initial stability of the implant after maxillary sinus reconstruction. The maxillary sinus augmentation methods include a crestal approach and a lateral approach. Less morbidity and complications after operation is major advantage to sinus augmentation using crestal approach than lateral approach. However, when the residual ridge height is ${\geq}6mm$, it is known that crestal approach is appropriate. Also delayed implantation after sinus augmentation is recommended in severely atrophic ridge. We present the three cases of implant placement simultaneously sinus augmentation using crestal approach in posterior maxilla site with ${\leq}3mm$ of residual alveolar bone.

• Journal of Periodontal and Implant Science
• /
• v.34 no.1
• /
• pp.101-112
• /
• 2004

Osseointegrated implnats have proven to be successful in both full and partial edentulous patients since the 1960s and recently have shown successful results when used to restore single tooth missing. However, in most studies reporting the success of single implants, single implants replacing anterior teeth are more frequently mentioned than posterior single implants. Moreover, in studies regarding posterior single implants, the replaced region seemed to be variable; the maxilla, mandible and areas from the first premolar to the second molar were mentioned. However, considering the difference in bone quality in the mandible and maxilla, and the increased occlusal force in the posterior region, the success rates in each region may be different. In this study, the cumulative success rates and amount of bone loss of single implants replacing the mandibular first and second molar, respectively, were compared and analyzed to come to the following conclusion. 1. The 20 (20 persons) single implants that were placed in the mandibular first molar region were all successful and showed a 100% 5 year cumulative success rate. Among the 27 (24 persons) single implants replacing the mandibular second molar, 8 failed (27.63%) showing a 5 year cumulative success rate of 70.37%. 2. Among the 8 failed implants, one showed symptoms of postoperative infection and one complained of parenthesia. 6 implants failed after functional loading; 5 showed mobility and one resulted in fixture fracture. 3. After the attachment of the prosthesis, there was no significant statistical difference regarding the marginal bone loss in group 1 and group 2 during the checkup period (P>0.05). In conclusion, restoration of the mandibular first molar using single implants was found to be an excellent treatment modality, and when replacing mandibular second molars with single implants, poor bone quality and risk of overloading must be considered.

• The Journal of Korean Academy of Prosthodontics
• /
• v.60 no.3
• /
• pp.263-275
• /
• 2022

The loss of posterior occlusal support leads to further complications such as collapsed occlusal plane and reduced vertical dimension, and it may cause problems such as facial appearance change, reduced chewing efficiency, and temporomandibular joint disorders. In such case, it is necessary to re-establish occlusal plane and vertical dimension properly through accurate diagnosis and predictable treatment plan. This case report presents a 71-year-old female, whose occlusal plane was collapsed and posterior restorative space was insufficient. To perform a patient-friendly full mouth rehabilitation, proper vertical dimension and occlusal plane were decided by evaluation of interocclusal space at her physiologic mandibular rest position, swallowing, pronunciation, facial appearance, and the average length of anterior teeth. And then, the fixed provisional restorations were fabricated with the new occlusal position, and evaluated for 5 months with checking adaptation of masticatory muscles and any kind of clinical symptoms occurs or not. After confirmation of functional stability and esthetic satisfaction with the newly established occlusion, final definitive restorations were fabricated and inserted in the mouth. Through the above process, the treatment result was functionally and aesthetically satisfactory.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.27 no.2
• /
• pp.27-47
• /
• 1997

The purpose of this study was to evaluate the accuracy and usefulness of spiral tomography through the comparison and analysis of SCANORA cross-sectional tomographs and DentaScan computed tomographic images of dry mandibles taken by a SCANORA spiral tomographic machine and a computed tomographic machine. Thirty-one dry mandibles with full or partial edentulous areas were used. To evaluate the possible effect of location in the edentulous area, it was divided into 4 regions of Me (region of mental foramen), MI (the midportion between Me and M2), M2 (the midportion between mental foramen and mandibular foramen) and S (the midportion of the mandibular symphysis). A ZPC column (sized 4 mm x 5 mm) was seated on the edentulous regions of Me, MI, M2 and S using the acrylic stent. Then SCANORA spiral tomography and computed tomography were taken on the edentulous regions which contained the ZPC column. The ZPC columns and cross-sectional images of the mandible were measured in the radiographs by three observers and the differences between the two imaging modalities were analysed. The results were as follows: 1. In comparing the actual measurements of the ZPC column and measurements in the radiographs, the mean error of the DentaScan computed tomography was 0.07 mm in vertical direction and -0.06 mm in horiwntal direction, while the mean error of the SCANORA spiral tomography was 0.06 mm in vertical direction and -0.12 mm in horizontal direction. There was a significant difference between the two radiographic techniques in the horizontal measurement of the ZPC column of the symphysis region (p<0.05). But there was no significant difference in the measurements of other regions (p>0.05). 2. In measurements of the distance from the alveolar crest to the inferior border of the mandible (H), and of the distance from the alveolar crest to the superior border of the mandibular canal (Y), there was no significant difference between the two radiographic techniques (p>0.05). 3. In measurements of the distance from the lingual border of the mandible to the buccal border of the mandible (W), and of the distance from the lingual border of the mandible to the lingual border of the mandibular canal (X), there was a significant difference between the two radiographic techniques in measurements of the midportion between the mental foramen and the mandibular foramen (M2) (p<0.05). But there were no significant differences in measurements of the other regions of symphysis (S), mental foramen (Me), the first one-fourth portion between the mental foramen and the mandibular foramen (M1) (p>0.05). 4. Considering the mean range of measurements between observers, the measurements of SCANORA spiral tomography showed higher value than those of DentaScan computed tomography, except in measurements of symphysis (S). 5. On the detectability of the mandibular canal, there was no significant difference between the two radiographic techniques (p>0.05). In conclusion, SCANORA spiral tomography demonstrated a higher interobserver variance than that of DentaScan computed tomography for implant site measurements in the posterior edentulous area of the mandible. These differences were mainly the result of difficulty in the detection of the border of the mandible in SCANORA spiral tomography. But considering the cost and the radiation exposure, SCANORA spiral tomography can be said to be a relatively good radiographic technique for implant site measurement.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.39 no.2
• /
• pp.94-99
• /
• 2013

Focal osteoporotic bone marrow defect (FOBMD) is a radiolucent area corresponding to the presence of hematopoietic tissue rarely found in the jaws. FOBMD is most commonly located in the mandibular edentulous posterior area of a middle-aged female. From November 2011 to November 2012, we experienced three cases involving removal of implants that had accidentally fallen into the FOBMD area. All patients happened to be female, with a mean age of 54 years (range: 51-60 years). One case involved hypoesthesia of the lower lip and chin, while two cases healed without any complication. Displacement of an implant into the FOBMD area is an unusual event, which occurs rarely during placement of a dental fixture. The purpose of this study was to report on three cases of FOBMD and to provide a review of related literature.

• Journal of Korean Dental Science
• /
• v.13 no.1
• /
• pp.28-34
• /
• 2020

Purpose: The purpose of this study was to investigate the influence of different implant computer software on the accuracy of image registration between radiographic and optical scan data. Materials and Methods: Cone-beam computed tomography and optical scan data of a partially edentulous jaw were collected and transferred to three different computer softwares: Blue Sky Plan (Blue Sky Bio), Implant Studio (3M Shape), and Geomagic DesignX (3D systems). In each software, the two image sets were aligned using a point-based automatic image registration algorithm. Image matching error was evaluated by measuring the linear discrepancies between the two images at the anterior and posterior area in the direction of the x-, y-, and z-axes. Kruskal-Wallis test and a post hoc Mann-Whitney U-test with Bonferroni correction were used for statistical analyses. The significance level was set at 0.05. Result: Overall discrepancy values ranged from 0.08 to 0.30 ㎛. The image registration accuracy among the software was significantly different in the x- and z-axes (P=0.009 and <0.001, respectively), but not different in the y-axis (P=0.064). Conclusion: The image registration accuracy performed by a point-based automatic image matching could be different depending on the computer software used.

• Journal of Periodontal and Implant Science
• /
• v.44 no.5
• /
• pp.259-264
• /
• 2014

Purpose: The aim of this case report is to present the longitudinal results of sinus grafting using a new demineralized bovine bone material (DBBM) in human cases. Methods: A patient with a resorbed maxilla was treated by maxillary sinus grafting using a new deproteinized bovine bone material. After a healing period of 6.5 months, three implants were placed and restored. The patient was periodically recalled and followed up for 5 years after restoration. Results: Twelve partially edentulous patients (average age, 55.7 years) were followed up. All patients had insufficient residual height in their maxillary posterior area and underwent maxillary sinus graft surgery to increase the height of their maxilla. In all, 27 fixtures were placed in the augmented bone area. On average, 8.6 months later, implants were loaded using provisional or final restorations. The observation period ranged from 27 to 75 months (average, 43.3 months), and the patients did not show any severe resorption of the graft material or any infection during this time. Conclusions: Our results show that the new DBBM is useful for a maxillary sinus graft procedure. Good healing responses as well as reliable results were obtained for an average follow-up period of 43.3 months.

• The Journal of Korean Academy of Prosthodontics
• /
• v.29 no.1
• /
• pp.215-232
• /
• 1991

In this study, oral sensory function in the osseointegrated root form implant-supported prostheses wearers was estimated by measuring occlusal tactile perception threshold of thickness and sensibility threshold against lateral static loading, and comparing with normal dentition subjects and complete denture wearers group. Osseointegrated root form implants seemed to be restored in the sensation to some extent, and so, dental implants restored edentulous patients in a wide meaning. Conclusions were summarized as following. 1. Occlusal tactile perception threshold of thickness was highest in complete denture wearers group, following by implant-supported prostheses wearers group, normal dentition subjects group. 2. In the implant-supported prostheses wearers group, occlusal tactile perception threshold of opposing artificial teeth case was higher than of opposing natural or opposing implantsupported teeth case. 3. Sensibility threshold against lateral loading of complete denture wearers and implantsupported prostheses wearers group was higher than that of normal dentition subject group. 4. In the implant-supported prostheses group, sensibility threshold against lateral loading was not significantly different between upper and lower jaws. 5. In occlusal tactile perception threshold of thickness and sensibility threshold against lateral loading test, there was no regularity among values of each tooth, and no significant difference between anterior and posterior teeth as well.