• The Journal of Korean Academy of Prosthodontics
• /
• v.57 no.3
• /
• pp.280-287
• /
• 2019

In the oral cavity, the teeth undergo wear and corrosion throughout their lives. Progressive and constant tooth wear is a natural phenomenon of aging, but wear and corrosion due to specific factors are pathological factors. It can cause pathological damage of the occlusal surface, aesthetic problems, dimensional loss and jaw joint disorders. This case is a 26-year-old female patient with general tooth abrasion and erosion on the entire dentition. Diagnostic wax-up was fabricated based on the information including digital facial analysis, physiological stabilization, and evaluation of anterior crown length. Through the digital analysis, the necessary guides for crown lengthening were prepared and the mastication function and esthetics were evaluated by using temporary crowns. Definitive prosthesis was fabricated with the zirconia restorations. The results were satisfactory when they were observed 3 months of follow-up.

• The Journal of the Korean dental association
• /
• v.56 no.11
• /
• pp.631-640
• /
• 2018

Nowadays computer-guided "flapless" surgery for implant placement using templates is gaining popularity among clinicians and patients. The advantages of this surgical protocol are its minimally invasive nature, accuracy of implant placement, predictability, less post-surgical discomfort and reduced time required for definitive rehabilitation. Aim of this study is to describe the digital implant protocol, thanks to which is now possible to do a mini-invasive static guided implant surgery. This is possible thanks to a procedure named surface mapping based on the matching between numerous points on the surface of patient's dental casts and the corresponding anatomical surface points in the CBCT data. With some critical points and needing an adequate learning curve, this protocol allows to select the ideal implant position in depth, inclination and mesio-distal distance between natural teeth and or other implants enabling a very safe and predictable rehabilitation compared with conventional surgery. It represents a good tool for the best compromise between anatomy, function and aesthetic, able to guarantee better results in all clinical situations.

• Journal of the Korean Academy of Esthetic Dentistry
• /
• v.27 no.2
• /
• pp.105-115
• /
• 2018

Not to recreate the final prosthesis is the shortest way to get a successful outcome. In the case of an aesthetic prosthesis, it is important not only the condition of the oral cavity but also the whole harmony in the face such as the interpupillary line and the smile line. But the dental technician creates the prosthesis only based on the oral model. So if you want to prevent the failure of the prosthesis due to discordance with the face, it is a good idea to use patient's facial photography and provisional restorations to reproduce facial features, shapes and aesthetics before switching to a final prosthesis. To prevent the failure of the final prosthesis, it is important to communicate among the patient, the technician and the doctor according to the model diagnosis, facial and oral photos. Then all the technicians will get satisfactory results. In addition, the technician have to understand the form of natural teeth, to analyze and reproduce colors, and to understand materials in order to produce a successful aesthetic prosthesis. From now on, I will explain two parts. At first, the communication in the dental office for the successful production of aesthetic prosthesis through the clinical case. And the second, my opinion for the successful aesthetic prosthesis.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.2
• /
• pp.120-127
• /
• 2019

PURPOSE. To determine wear amount of single molar crowns, made from four different restoratives, and opposing natural teeth through computerized fabrication techniques using 3D image alignment. MATERIALS AND METHODS. A total of 24 single crowns (N = 24 patients, age range: 18 - 50) were made from lithium disilicate (IPS E-max CAD), lithium silicate and zirconia based (Vita Suprinity CAD), resin matrix ceramic material (Cerasmart, GC), and dual matrix (Vita Enamic CAD) blocks. After digital impressions (Cerec 3D Bluecam, DentsplySirona), the crowns were designed and manufactured (Cerec 3, DentsplySirona). A dualcuring resin cement was used for cementation (Variolink Esthetic DC, Ivoclar). Then, measurement and recording of crowns and the opposing enamel surfaces with the intraoral scanner were made as well as at the third and sixth month follow-ups. All measurements were superimposed with a software (David-Laserscanner, V3.10.4). Volume loss due to wear was calculated from baseline to follow-up periods with Siemens Unigraphics NX 10 software. Statistical analysis was accomplished by Repeated Measures for ANOVA (SPSS 21) at = .05 significance level. RESULTS. After 6 months, insignificant differences of the glass matrix and resin matrix materials for restoration/enamel wear were observed (P>.05). While there were no significant differences between the glass matrix groups (P>.05), significant differences between the resin matrix group materials (P<.05) were obtained. Although Cerasmart and Enamic were both resin matrix based, they exhibited different wear characteristics. CONCLUSION. Glass matrix materials showed less wear both on their own and opposing enamel surfaces than resin matrix ceramic materials.

• Journal of the Korean Academy of Esthetic Dentistry
• /
• v.29 no.2
• /
• pp.66-74
• /
• 2020

Communication and cooperation between dentists and dental technicians are two essential elements for the fabrication of high quality 'custom' prosthesis. For successful communication and cooperation between the two groups, however, dentists and dental technicians must share common understanding about clinical dentistry. Ironically, it is often noticed that they are not really sharing the same clinical knowledge. Although there is a strong association between 'Emergence Profile' of implant prostheses and periodontal health or esthetics, no definite guideline has ever been provided for ideal emergence profile of implant prosthesis in literature. Problems resulted from inherent differences between implants and natural teeth must be acknowledged and shared between dentists and dental technicians so that they can come up with desirable clinical results with implant prostheses.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.3
• /
• pp.171-177
• /
• 2022

Peri-implantitis is an inflammatory lesion of the periodontium surrounding an endosseous implant, with progressive loss of the supporting peri-implant bone. The main purposes of treatment for peri-implantitis due to biological factors include addressing the inflammation and restoring a healthy but reduced periodontium around the implant, similar to the treatment of periodontitis in natural teeth. The proposed treatment protocol includes surgical treatment, mainly resective surgery, after non-surgical treatment such as oral hygiene instructions, mechanical cleansing of the fixture, and general or topical antiseptic or antibiotic application according to the extent of inflammation. In this article, we present a 6-year follow-up case showing unusual marginal bone regeneration after resective surgery and decontamination of an implant surface for the treatment of peri-implantitis and discuss the possible reasons.

• Journal of Korean society of Dental Hygiene
• /
• v.22 no.5
• /
• pp.333-340
• /
• 2022

Objectives: This study aimed to confirm the association between cognitive function and oral health status in the elderly. Methods: In this study, 5,794 respondents, aged 55 or older, who had participated in the 7th aging research panel survey were used. Statistical analyses were performed using a complex samples cross-tabulation analysis, complex samples general linear model, and a complex sample multinomial logistic regression analysis. Results: After analyzing the cognitive function of the elderly according to their oral health conditions, it was found that suspicions of dementia (19.6%) and cognitive function decline (25.9%) were more common for those who wore dentures than for those who did not wear dentures (p<0.001). Compared to those who did not wear dentures, those who wore dentures were linked to a 1.665 times higher suspicion of dementia (p<0.001). In comparison, cognitive decline was 0.964 times lower when the number of natural teeth increased by 1, and it was 0.941 times lower when the oral health evaluation index for the elderly increased by 1 point (p<0.001). Conclusions: As a result of this study, it was confirmed that cognitive function and oral health status are related in the elderly. Therefore, systematic measures for oral health management and oral health promotion should be prepared in tandem with awareness of possible cognitive decline in the elderly.

• Imaging Science in Dentistry
• /
• v.52 no.4
• /
• pp.383-391
• /
• 2022

Purpose: Periodontitis, the most prevalent chronic inflammatory condition affecting teeth-supporting tissues, is diagnosed and classified through clinical and radiographic examinations. The staging of periodontitis using panoramic radiographs provides information for designing computer-assisted diagnostic systems. Performing image segmentation in periodontitis is required for image processing in diagnostic applications. This study evaluated image segmentation for periodontitis staging based on deep learning approaches. Materials and Methods: Multi-Label U-Net and Mask R-CNN models were compared for image segmentation to detect periodontitis using 100 digital panoramic radiographs. Normal conditions and 4 stages of periodontitis were annotated on these panoramic radiographs. A total of 1100 original and augmented images were then randomly divided into a training (75%) dataset to produce segmentation models and a testing (25%) dataset to determine the evaluation metrics of the segmentation models. Results: The performance of the segmentation models against the radiographic diagnosis of periodontitis conducted by a dentist was described by evaluation metrics(i.e., dice coefficient and intersection-over-union [IoU] score). MultiLabel U-Net achieved a dice coefficient of 0.96 and an IoU score of 0.97. Meanwhile, Mask R-CNN attained a dice coefficient of 0.87 and an IoU score of 0.74. U-Net showed the characteristic of semantic segmentation, and Mask R-CNN performed instance segmentation with accuracy, precision, recall, and F1-score values of 95%, 85.6%, 88.2%, and 86.6%, respectively. Conclusion: Multi-Label U-Net produced superior image segmentation to that of Mask R-CNN. The authors recommend integrating it with other techniques to develop hybrid models for automatic periodontitis detection.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.1
• /
• pp.60-68
• /
• 2022

A patient with severe periodontitis has causative factors that cause pathological tooth movement, the occlusion is disintegrated, and the vicious cycle of worsening periodontitis is repeated. In particular, when pathological tooth movement occurs in the maxillary anterior region, the patient has an aesthetic sense of atrophy, and the quality of life was reduced. Therefore, when orthodontic treatment was added to patients with severe periodontitis, it promotes the formation of new bone, reduces periodontal cysts, and obtains clinical attachment, which leads to favorable results in prosthetic restoration, thereby enabling ideal occlusion, function and aesthetics. Periodontal treatment, orthodontic treatment, natural tooth restoration, and implant prosthesis were planned for patients with pathological tooth movement in the anterior region due to loss of occlusal support in the posterior region. As a result, an ideal restoration space was secured, a stable restoration of occlusal contact was formed, and the maxillary anterior teeth were aesthetically improved.

• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.2
• /
• pp.271-300
• /
• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstrcture. This investigation evaluated the stress patterns in a photoelastic model produced by three different types of dental implants such as Branemark, Steri-Oss, IMZ and resin tooth using the techniques of quasi three dimensional photoelasticity. The teeth-supported bridge had a first molar pontic supported by second premolar and second molar as a control group. The implant and toothsupported bridge had a first molar pontic supported by second premolar and implant posterior retainer as an experimental group. Prostheses were mechanically connected to an adjacent second premolar by the rigid of nonrigid connection, Nonrigid connection used an attachment placed between the tooth-supported and fixture-supported component. The female(keyway) of attachment was placed on the distal end of the retainer supported by the tooth ; the male(Key) of attachment connected to the osseointegrated bridge was engaged into the keyway. All prostheses were casted in the same nonprecious alloy and were cemented and screwed on their respective abutments and implants. 16㎏ of vertical loads on central fossae of second premolar, first molar pontic, implant of second molar were applied respectively and 6.5㎏ of inclined load on middle buccal surface of first molar pontic was applied. The results were as follows : 1. Under the vertical load on the central fossa of first mloar pontic, the stress developed at the apex of tooth of implat was more uniformly distributed in the case of nonrigid connection than in the case of rigid connection. 2. Under the vertical load on the central fossa of first molar pontic, the stress developed around the cervical area of tooth of implant was larger in the case of rigid connection than in the case of nonrigid connection because the bending moment was more occured in the case of rigid connection than in the case of nonrigid connection. 3. Stress was more restricted to the loaded side of nonrigid connection than to that of rigid connection 4. Under the inclined load. The set screw loosening of implant was more easily occured in the case of nonrigid connection than in the case of rigid connection due to torque moment. 5. In the case of Branemark implant, the stress concentration in second premolar was larger and the stress developed around the cervical area of implant was lower than any other cases under the vertical load, because Branemark implant with the flexible gold screw was showed in incline toward second premolar by a bending moment. 6. The stress developed around the apex of tooth or implant was more uniformly distributed in the case of Steri-Oss implant with stiff screw than in the case of Branemark implant under the vertical load. But, the stress developed around the cervical area of the Steri-Oss implant was larger than that of any other implants because bending moment was occured by vertical migration of second premolar. 7. The stress distribution in the case of IMZ implant was similar to the case of natural teeth under small vertical load. But, the residual stress around the implant was showed to occurdue to deformation of IMC and sinking of screw under larger vertical load.