• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.22 no.3
• /
• pp.337-342
• /
• 2000

Purpose : The purpose of this study was to analyze the lower third facial changes in frontal view after mandibular setback surgery. Materials and Methods : In this study, fifteen subjects(6 males and 9 females) with class III dental and skeletal malocclusions who were treated with BSSRO(Bilateral Sagittal Split Ramus Ostetomy) were used. Frontal cephalometric radiographs were taken preoperatively and more than 6 months postoperatively, and hard tissue(H2-Hl) and soft tissue changes (S2-S1) were measured on vertical and horizontal reference lines. In 15 cases, changes which developed more than 6 months after surgery were studied. Results : The results were as follows. 1. In the facial height, hard tissue $decreased(2.46{\pm}2.76mm)$ with statistical significance(P<0.01), and soft tissue also $decreased(1.64{\pm}3.66mm)$. As a result, the facial height generally becomes shorter after sagittal split ramus osteotomy. 2. In the mandibular width, hard tissue $decreased(2.08{\pm}3.59mm)$ with statistical sgnificance(P<0.05), but soft tissue $increased (2.14{\pm}5.73mm)$ without statistically significant difference(P>0.05) postoperatively. 3. In the facial index, hard tissue $decreased(0.23{\pm}2.21%)$, but soft tissue $increased(2.41{\pm}3.46%)$ with statistical significance. Conclusion : One of the main purpose of orthognathic surgery is to achieve facial esthetics and harmony. In order to fullfill this purpose, it is important to carry out a precise presurgical treatment planning by estimating the changes of frontal profile after surgery.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.16 no.2
• /
• pp.149-159
• /
• 2000

Occlusal disease is comparable to periodontitis in that it is generally not reversible. Occlusal disease, however, like periodontitis, often maintainable. It does itself to treatment and when restorative dentistry is utilized it becomes, in that sense, reversible. Moreover, a systematized and integrated approach will lead to a prognosis that is favorable and predictable. This approach facilitates development of optimum oral function, comfort, and esthetics, resulting in a satisfied patient. Such a systematized approach consists of four logical phase : (1) patient evaluation, (2) comprehensive analysis and treatment planning, (3) integrated and systematic reconstruction, and (4) postoperative maintenance. An integrated treatment plan is first developed on one set of diagnostic casts, properly mounted on a semiadjustable articulator using jaw relationship records. This is accomplished by using wax to make reconstructive modifications to the casts. These modified casts become the blueprint for planned occlusal changes and the fabrication of provisional restorations. The treatment goals are : (1) comfortably functioning temporomandibular joints and stomatognathic musculature, (2) adherence to the basic principle of occlusion advocated by Schuyler, (3) anterior guidance that is in harmony with the envelope of function, (4) restorations that will not violate the patient's neutral zone. This report shows the treatment procedures for a patient whose mandibular position has been altered due to posterior bite collapse. Migration of the maxillary anterior teeth had occurred, and the posterior occlusal contacts showed pathologic interference. Precise diagnosis using mounted casts was executed and prosthodontic reconstruction by the aid of an unconventional orthodontic correction on maxillary flaring was planned. An unconventional orthodontic correction can be accomplished by using preexisting natural teeth, which can be modified for use in active tooth movement or splinted together for orthodontic anchorage. This technique has an advantage over conventional fixed appliance orthodontic therapy because it can accomplish tooth movement concurrently with restorative and periodontal therapy. On occasion, minor tooth movement can be necessary to achieve the optimum occlusal scheme, crown form, and tooth position for the forces of occlusion to be displaced down the long axis of the periodontally compromised teeth. Once the occlusion, periodontal health, and crown contours for the provisional splinted restoration are acceptable, the final splinted restoration can be similarly fabricated, and it becomes an excellent orthodontic retainer.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.16 no.2
• /
• pp.133-147
• /
• 2000

A well-planned, precise occlusal adjustment of natural teeth has some distinct advantages over other forms of occlusal therapy. It should be emphasized, however, that an occlusal adjustment is an irreversible procedure and has definite contraindications in some mouths. Generally, the treatment methods for the patients that has open-bite will be following as below. : (1) Use of removable orthopedic repositioning appliance, (2) Orthodontics, (3) Full or partial reconstruction of the dentition, (4) Orthognathic surgical procedure, (5) Occlusal adjustment of the existing natural teeth, (6) Any combination of the above. Above all, the advantages of occlusal adjustment of natural teeth are : (1) the patient is more able to adapt to the changes in jaw position and posture; (2) the phonetic or speaking ability of the patient is not significantly changed and usually is improved; (3) the esthetics of the natural teeth is not altered and often is better; (4) the hygiene of the individual teeth is easily maintained; and (5) the functional usage of the teeth as cutting and chewing devices is markedly improved. The objective of an occlusal adjustment, as with any form of occlusal therapy, is to correct or remove the occlusal interferences, or premature contacts, on the occluding parts of the teeth which prevent a centric relation closure of the mandible. A systematic, disciplined approach can be followed in treatment, the objectives should be listed. They are : (1) Centric relation occlusion of the posterior teeth. (2) Proper "coupling" of the anterior teeth. (3) An acceptable disclusive angle of the anterior teeth in harmony with the condylar movement patterns. (4) Stability of the corrected occlusion. (5) Resolution of the related symptoms. For the patient with open-bite on anterior and posterior teeth, this case report shows the treatment methods in combination the fixed prosthesis with the selective cutting of the natural teeth. Occlusal adjustment is no longer an elective procedure but a mandatory one for patients requiring restorations and those in treatment for TMD dysfunctions or those whose dentitions show signs of occlusal trauma. Occlusal adjustment is essential for all who do not display the above lists.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.16 no.3
• /
• pp.171-185
• /
• 2000

The treatment objectives of the complete oral rehabilitation are : (1) comfortably functioning temporomandibular joints and stomatognathic musculature, (2) adherence to the basic principle of occlusion advocated by Schuyler, (3) anterior guidance that is in harmony with the envelope of function, (4) restorations that will not violate the patient's neutral zone. There may be many roads to achieving these objectives, but they all convey varing degrees of stress and strain on the dentist and patient. There are no "easy" cases of oral rehabilitation. Time must be taken to think, time must be taken to plan, and time must be taken to perform, since time is the critical element in both success and failure. Moreover, a systematized and integrated approach will lead to a prognosis that is favorable and predictable. This approach facilitates development of optimum oral function, comfort, and esthetics, resulting in a satisfied patient. Such a systematized approach consists of four logical phase : (1) patient evaluation, (2) comprehensive analysis and treatment planning, (3) integrated and systematic reconstruction, and (4) postoperative maintenance. Firstly, we must evaluate the mandibular position. The results of a repetitive, unstrained, nondeflective, nonmanipulated mandibular closure into complete maxillomandibular intercuspation is not so much a "centric" occlusion as it is a stable occlusion. Accordingly, we ought to concern ourselves less with mandibular centricity and more with mandibular stability, which actually is the relationship we are trying to establish. The key to this stability is intercuspal precision. Once neuromuscular passivity has been achieved during an appropriate period of occlusal adjustment and provisionalization, subsequent intercuspal precision becomes the controlling factors in maintaining a stable mandibular position. Secondly, we must evaluate the planned vertical dimension of occlusion in relationship to what may now be an altered(generally diminished), and avoid the hazard of using such an abnormal position to indicate ultimate occlusal contacting points. There are no hard and fast rules to follow, no formulas, and no precise ratios between the vertical dimension of occlusion. Like centric relation, it is an area, not a point.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.32 no.4
• /
• pp.314-321
• /
• 2016

Conventional removable partial dentures (RPDs) with distal extensions are associated with some problems, including lack of stability that calls for frequent relining, and cantilever actions of claps that can produce excessive loading to abutment teeth, and the need for unesthetic retentive arm clasps. Therefore, IARPDs (Implant-assisted RPD) that use implants to support or retain RPDs has been reported to improve stability, esthetics and masticatory performance of RPDs. Also, an IARPD that has zirconia occlusal table can prevent the incongruity of occlusal plane and the extrusion of antagonistic tooth. In this case of partially edentulous patient with crossed occlusion, each edentulous area was restored with implant fixed prosthesis and implant retained partial denture to suit each situation. Through the procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.37 no.2
• /
• pp.73-80
• /
• 2021

Purpose: The purpose of this study is to compare the color stability of provisional restorative materials fabricated by subtractive and additive manufacturing. Materials and Methods: PMMA specimens by subtractive manufacturing and conventional method and bis-acryl specimens by additive manufacturing were fabricated each 20. After immersing specimens in the coffee solution and the wine solution, the color was measured as CIE Lab with a colorimeter weekly for 4 weeks. Color change was calculated and data were analyzed with one-way ANOVA and the Tukey multiple comparisons test (α = 0.05). Results: PMMA provisional prosthetic materials by subtractive manufacturing showed superior color stability compared to bis-acryl provisional prosthetic materials by additive manufacturing (P < 0.05), and showed similar color stability to the PMMA provisional prosthetic materials by conventional method (P > 0.05). Conclusion: It is recommended to fabricate provisional restorations by subtractive manufacturing in areas where esthetics is important, such as anterior teeth, and consideration of the color stability will be required when making provisional prosthetic using additive manufacturing.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.4
• /
• pp.367-378
• /
• 2023

With the recent development of computer-aided design-computer-aided manufacturing technology and 3D printing technology, and the introduction of various digital techniques, the accuracy and efficiency of top-down definitive prosthetic restoration are increasing. In this clinical case, stable occlusion support was obtained through the placement of a total of 9 maxillary and mandibular posterior implants in patient with anterior-posterior crossed occlusion. The edentulous area of the maxillary anterior teeth, which showed a tendency of high resorption of the residual alveolar bone, was restored with a Kennedy Class IV implant assisted removable partial denture to restore soft tissue esthetics. Computed tomography guided surgery was used to place implants in the planned position, double scan technique was used to reflect the stabilized occlusion in the interim restoration stage to the definitive prostheses, and metal 3D printing was used to manufacture the coping and framework. This clinical case reports that efficient and predictable top-down full mouth rehabilitation was achieved using various digital technologies and techniques.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.3
• /
• pp.194-201
• /
• 2010

Purpose: The purpose was to compare the marginal fidelity and the fracture resistance of the zirconia crowns according to the various coping designs with different thicknesses and cement types. Materials and methods: Zirconia copings were designed and fabricated with various thicknesses using the CAD/CAM system (Everest, KaVo Dental GmbH, Biberach., Germany). Eighty zirconia copings were divided into 4 groups (Group I: even 0.3 mm thickness, Group II: 0.3 mm thickness on the buccal surface and the buccal half of occlusal surface and the 0.6 mm thickness on the lingual surface and the lingual half of occlusal surface, Group III: even 0.6 mm thickness, Group IV: 0.6 mm thickness on the buccal surface and the buccal half of occlusal surface and the 1.0 mm thickness on the lingual surface and the lingual half of occlusal surface) of 20. By using a putty index, zirconia crowns with the same size and contour were fabricated. Each group was divided into two subgroups by type of cement: Cavitec$^{(R)}$ (Kerr Co, USA) and Panavia-$F^{(R)}$ (Kuraray Medical Inc, Japan). After the cementation of the crowns with a static load compressor, the marginal fidelity of the zirconia crowns were measured at margins on the buccal, lingual, mesial and distal surfaces, using a microscope of microhardness tester (Matsuzawa, MXT-70, Japan, ${\times}100$). The fracture resistance of each crown was measured using a universal testing machine (Z020, Zwick, Germany) at a crosshead speed of 1 mm/min. The results were analyzed statistically by the two-way ANOVA and oneway ANOVA and Duncan's multiple range test at $\alpha$=.05. Results: Group I and III showed the smallest marginal fidelity, while group II demonstrated the largest value in Cavitec$^{(R)}$ subgroup (P<.05). For fracture resistance, group III and IV were significantly higher than group I and II in Cavitec$^{(R)}$ subgroup (P<.05). The fracture resistances of Panavia-$F^{(R)}$ subgroup were not significantly different among the groups (P>.05). Panavia-$F^{(R)}$ subgroup showed significantly higher fracture resistance than Cavitec$^{(R)}$ subgroup in group I and II (P<.05). Conclusion: Within the limitation of this study, considering fracture resistance or marginal fidelity and esthetics, a functional ceramic substructure design of the coping with slim visible surface can be used for esthetic purposes, or a thick invisible surface to support the veneering ceramic can be used depending on the priority.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.27 no.2
• /
• pp.209-222
• /
• 2011

Missing anterior teeth can be replaced using any of a number of methods. Patients may choose to replace missing teeth with a prosthesis that is either removable, fixed, or retained with implants. For patients faced with financial, anatomical, and/or esthetic limitations, the edentulous region can be restored successfully and esthetically with a properly designed and fabricated rotational path RPD. The rotational path RPD is a partial removable dental prosthesis that incorporates a curved, arcuate, or variable path of placement allowing one or more of the rigid components of the framework to gain access to and engage an undercut area. The rigid retainer must gain access to the infrabulge portion of the tooth by rotating into place. Either a minor connector or proximal plate provides retention through its intimate contact with a proximal tooth surface. A specially designed dovetails or asymmetric rest seats provides support and embracing effects. Correctly designed and fabricated rotational path RPD can provide improved esthetics, cleanliness, and retention. But rotational path RPDs are technique sensitive since the rotational path RPD has little margin of laboratory error that rigid retainers cannot be adjusted like conventional clasps can, RPD framework must be remade once the retention is lost. The sufficient understanding of the concept for the rotational path RPD is required for clinically successful treatment. This clinical report describes in detail the theoretical, laboratory considerations and the treatment of a patient with an anterior maxillary edentulous area treated by an AP path rotational RPD that had a difficulty in long term maintenance and describes another clinical case in which more reasonable treatment procedures were approached after analyzing the former case.

• The Journal of Korean Academy of Prosthodontics
• /
• v.59 no.4
• /
• pp.487-496
• /
• 2021

Full mouth rehabilitation is re-organizing the occlusion of the remaining teeth and missing teeth considering the functions, esthetics, and neuromuscular harmony. With the loss of multiple teeth, the patient's occlusal plane gradually collapses and the vertical dimension can be reduced. Since reduced vertical dimension can be a potential etiology of the temporomandibular joint and masticatory muscles, prosthetic restoration with increased vertical dimension is required. This case report is about a 68 years old patient with vertical dimension loss due to worn dentition and multiple loss of teeth. In this case, the loss of vertical dimension is assessed carefully using the digital dentistry technology. Using CAD software in digital analysis step, the occlusal plane was established and evaluated using several criteria. Orienting the position of the bone and teeth using CBCT image, patient's condition was visualized in 3 dimension and treatment planning was possible virtually. The information that matches the patient's condylar position with the articulator, which is the virtual face bow, is reproduced on the actual articulator, and evaluated again. After the evaluation, provisional prosthesis was fabricated and it was confirmed that the patient adapts without any abnormality. This was implemented as a final prosthesis. As a result, the patient obtained satisfying results, utilizing the benefits of digital dentistry technology and traditional methods.