• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.3
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• pp.247-256
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• 2003

The patient had bruxism and epilepsy tendency. Inadequate or unstable posterior support was identified due to severe anterior attrition and decreased occlusal vertical dimension. Prematurities of posterior occlusal and wear facets increased the function of anterior teeth, resulting in severe wear. Wear facets displayed sharply defined peripheries, which are matched on articulated diagnostic casts. Also the patient showed C III malocclusion tendency, and lost some facial contour with drooping corners on the mouth. In this case, the alteration of OVD (Occlusal Vertical Dimention) may provide a biologically compatible adjunct to the treatment such as dentofacial esthetics, improved visual proportion in facial heightand mechanical solutions to the force-management of the masticatory system. The patient requires extensive restorative treatment to regain appropriate function, esthetics and comfort. According to the report by Farhad Fays, the average vertical distance from the maxillary to the mandibular mucolabial reflection in the region of the central incisors is approximately 34mm. However, the vertical distance of this patient was found to be 32mm, which was necessary to add gauge 20-sheets to apply vertical dimension. A removable occlusal overlay splint, which restores OVD to the estimated optimalposition, is the general first trial. The patient was observed periodically for 6 weeks, while appropriate adjustments were made vertical dimension to function. When patient felt comfortable with the splint, the teeth were prepared, and provisional restorations are placed for 3 months. The provisional restoration was fabricated by a diagnostic wax-up. When the patient felt comfortable with the provisional restoration, the final restoration mimics OVD, function, and esthetics that have been developed in the treatment restorations. Restoration of the extremely worn dentition presents a substantial challenge to thedentists. Therefore, careful evaluation of the etiology, history, and factors associated with occlusal vertical dimension should be preceded prior to the appropriate treatment planning.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.382-388
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• 2019

Increased anterior teeth mastication following posterior teeth loss leads to greater anterior occlusal force. It may cause greater attrition of anterior teeth, traumatic force occlusion (TFO), also often followed by antagonist extrusion and occlusal disharmony. This clinical report describes the treatment for a 67-year-old female patient diagnosed with loss of both maxillary and left mandibular posterior teeth, severe attrition of maxillary and mandibular anterior teeth and extrusion of multiple teeth. A diagnostic cast was mounted on articular in centric relation (CR) position to evaluate vertical dimension (VD) and interspace. To provide adequate space for the prosthetic reconstructions, VD was increased by 3 mm on the anterior pin. And then diagnostic wax-up was completed upon that VD. Wax-up was converted to provisional restorations and verified in the patient's mouth and the final restorations were delivered. Clinical follow up examination held 3 months after temporary restoration owing to changes in vertical dimension revealed proper function in mastication without evidence of temporo-mandibular joint (TMJ) disorders. This clinical report presents successfully restoring severe attrition case with increasing vertical dimension resulting in satisfaction in esthetics and function.

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

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.358-394
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• 1995

The author studied the actual conditions on the production of dental prosthesis made in laboratories, and also studied interrelationships between dentists and laboratory technicians in both personal and technical aspects. Two hundred-eighty four technicians, work in dental laboratories presently, were surveyed via mail and direct contact during the period from June 1 to June 30 and August 27 to August 28 in 1994 respectively. The obtained results were as follows : 1. Among the respondents, 90.5% we re working in commercial dental laboratories and their laboratories were mainly located in the Seoul area(40.9%, P<0.05). The numbers of employees in these laboratories were less than 10 persons(70.0%, P<0.01), and 75.9% of these laboratories have been in operation less than 15 years. 2. Most laboratory procedures were accomplished according to established disciplines. However, procedures such as die trimming in fixed restorations and the qualifications of the people designing removable partial dentures were not. Other problem areas were boxing of the working cast, the person determining the posterior palatal seal area, selection and arrangement of artificial teeth, occlusion rim correction and laboratory remounting of the processed denture in complete denture restorations. 3. Only half of the requesting dentists could send work authorizations to the laboratories with their work and even so, its contents were quite lacking. Consequently, there must be some standards in writing work authorization. 4. Technicians most desired clean and accurate impressions in fixed and removable dentures, and enough tooth reduction in porcelain fused to metal restorations. 5. For the establishment of better relationships between dentist and dental technician, the respondents desired the establishment of equal footing first(33.5%), and frequent conversations and muture understanding second(25.9%).

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.76-83
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• 2012

PURPOSE. Zirconia has been used in clinical dentistry for approximately a decade, and there have been several reports regarding the clinical performance and survival rates of zirconia-based restorations. The aim of this article was to review the literatures published from 2000 to 2010 regarding the clinical performance and the causes of failure of zirconia fixed partial dentures (FPDs). MATERIALS AND METHODS. An electronic search of English peer-reviewed dental literatures was performed through PubMed to obtain all the clinical studies focused on the performance of the zirconia FPDs. The electronic search was supplemented by manual searching through the references of the selected articles for possible inclusion of some articles. Randomized controlled clinical trials, longitudinal prospective and retrospective cohort studies were the focuses of this review. Articles that did not focus on the restoration of teeth using zirconia-based restorations were excluded from this review. RESULTS. There have been three studies for the study of zirconia single crowns. The clinical outcome was satisfactory (acceptable) according to the CDA evaluation. There have been 14 studies for the study of zirconia FPDs. The survival rates of zirconia anterior and posterior FPDs ranged between 73.9% - 100% after 2 - 5 years. The causes of failure were veneer fracture, ceramic core fracture, abutment tooth fracture, secondary caries, and restoration dislodgment. CONCLUSION. The overall performance of zirconia FPDs was satisfactory according to either USPHS criteria or CDA evaluations. Fracture resistance of core and veneering ceramics, bonding between core and veneering materials, and marginal discrepancy of zirconia-based restorations were discussed as the causes of failure. Because of its repeated occurrence in many studies, future researches are essentially required to clarify this problem and to reduce the fracture incident.

• The Journal of Korean Academy of Prosthodontics
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• v.18 no.1
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• pp.37-47
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• 1980

The purpose of this study was to investigate the stresses in different proximal margins and to measure, quantitatively, the effect of different modifications in the design of preparations on the stresses using two-dimensional photoelasticity. Photoelastic stress analysis is based on the phenomenon, exhibited by most transparent solids, of becoming birefringent, or doubly refracting, when strained. Two birefringent materials were used in this study, PSM-1 and PSM-5 in .standard sheet ($10'{\times}10'{\times}\frac{1}{4}'$ thickness), PSM-1(polyester) was used for constructing the substructure, and PSM-5(epoxy resin) was used in making the restorations to be investigated. Two birefringent materials were used in the construction of composite photoelastic model. Seven variable models were constructed. The peripheral dimensions of all model were constant and the models represent an occlusomesial section of a lower posterior molar. Model 1 represents the knife edge margin (shoulderless), Model 2 represents the chamfer, Model 3 represents a rounded shoulder(no sharp angle between the axial wall and gingival floor), Model 4 represents a flat shoulder (axial wall is a $90^{\circ}$ angle to the gingival wall), Model 5 represents $+15^{\circ}$ angulation, Model 6 has a $-15^{\circ}$ angulation, and Model 7 is the same as Model 4 except that it has a $45^{\circ}$ bevel. Improved artificial stone was used to represent dental cement in luting the composite photoelastic model. Static loading procedures(100 pounds) were used at preplanned sites. The results were as follows; 1. The stresses in the proximal portion of all tested models were compressive in nature when the proximal shoulders were loaded vertically on the same proximal marginal ridge. 2. The round and chamfered preparations were the optimum designs in proximoocclusal restorations. They showed the lowest stress concentration factor, i.e. 2.16 and 2.23, respectively. The knife edged shoulder had the highest value, K=5.39. Round type shoulder geometry experiments reduced the stress concentration factor (S.C.F.) 3. The gingival portion of proximal shoulder geometry was a critical location for stress concentration.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.258-272
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• 1998

This investigation evaluated patients who received Steri-Oss implants from the Dental Hospital of Chosun University during the period from March 1989 to August 1997. 346 fixtures of 127 patients were included in this study. The results were as follows ; 1.The follow-up period was defined as the period between the surgical placement of the implants and the last follow-up examination. The mean follow-up period was $2.17{\pm}1.21$ years. 2.The period between fixture installation and second surgery was $0.71{\pm}0.44$ years in the maxilla and $0.46{\pm}0.21$ years in the mandible. 3.The number of fixtures which were installed in the upper jaw(112) was less than that in the lower jaw(234) and in the posterior region(260) was more than in the anterior region(86). 4.The length of fixture which was most frequently used was 12 mm and least was 8mm. Screw implants were installed more than cylindrical implants. 3.8mm implant was the most common implans, followed by 4.5mm and 3.25mm. 5.The number of augmentation cases was more than that of non-augmentation cases and the rate of augmentation cases in the maxilla was more than that in the mandible. 6.Implant restorations for partial edentulos patients(94cases) were more than single- tooth implant restorations(33cases) or implant restorations for complete edentulos patients(10cases). 7.Free-standing prostheses for partially edentulous patients were more commom than any other type of connection between implants and natural teeth. 8.Plaque Index($0.95{\pm}0.74$) and Gingival Index($0.31{\pm}0.52$) were very similar around the natural teeth and reflected an acceptable level of plaque and gingivitis control. Mean value for keratinized mucosa index($1.93{\pm}1.20$) remained fairly constant around level 2(1-2 mm keratinized epithelium). 9.Patients were generally satisfied with implant in terms of comfort, function, speech and esthetics. 10.There was not a statistically significant differences in overall survial rate between implants placed in the maxilla (91.5%) and those placed in the mandible (93.8%). Fourteen implants lost before the prosthetic rehabilitation and eleven implants lost following variable periods in function after the prosthetic phase of the treatment. 11.Cause of implant failures was exfoliation or removal of fixture due to non-osseointegration before the prosthetic rehabilitation or due to fracture of fixture, masticatory pain after the prosthetic rehabilitation. 12.The survival rate of Steri-Oss implants using the Kaplan-Meier statistical analysis was 93.8% at 2 year and 86.6% at 5 year, In all cases, implant losses occured predominantly in the healing period. There was a steep decline in the rate of implant loss after the first year. 13.The survival rate of Steri-Oss implants in the anterior region was 94.8% at 2 year and 94.8% at 5 year and that in the posterior region was 92.8% at 2 year and 75.9% at 5 year. In conclusion, this study revealed a number of parameters and guidelines for achieving an optimal success rate in osseointegration.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.618-629
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• 1998

CAD/CAM-fabricated ceramic restorations nowadays are used as alternatives of amlagam and posterior composite resin restorations, especially in the cases of inlay restorations. But the reported results on marginal and internal fit of CAD/CAM-fabricated ceramic inlay have showed considerable difference. In this study, to evaluate the marginal and internal fit of CEREC2-fabricated ceramic inlay restoration and to compare with the fit of gold inlay and amalgam restoration, standardized Class II MO cavities were prepared in forty extracted caries-free human premolars. The teeth with prepared cavities were divided into 4 groups of ten teeth each. In group 1, CEREC2-fabricated ceramic inlays were treated with Scotchbond Multi-Purpose Plus(SMP plus) and cemented with Scotchbond Resin Cement. In group 2, casted gold inlays were cemented in the same method as in group 1. In group 3, casted gold inlays were cemented with zinc-phosphate cement. And in group 4, the prepared cavities were restored with amalgam. Restored teeth were thermocycled, stored in 1% methylene blue for 24 hours, and sectioned faciolingually and mesiodistally using EXAKT. Sectioned surfaces were observed with stereomicroscope and the gaps were measured at 9 points of mesiodistally sectioned surface and 7 points of faciolingually sectioned surface. The measured data were treated by Kruskal-Wallis one way ANOVA and Student-Newman-Keuls test. 1. The differences among measured gaps at each points were statistically significant for 4 experimental groups (P<0.05). 2. There were statistically significant differences in the measured gaps at each points between group 1 and group 2, group 1 and group 3, group 1 and group 4, group 2 and group 4, and group 3 and group 4 (P<0.05). 3. There were not statistically significant differences in the measured gaps at each points between group 2 and group 3 (P>0.05). 4. In the cases of inlay restorations(group 1, group 2, group 3), the gaps at internal line angle(distopulpal, axiogingival, faciopulpal, linguopulpal line angle) had a tendency to increase. In the cases of amalgam restorations(group 4), the gaps at occlusal margin, gingival margin and axiogingival line angle were greater than those at the other parts of cavities. 5. In CEREC2-fabricated ceramic inlays which were treated with Scotchbond Multi-Purpose Plus and cemented with Scotchbond Resin Cement, the mean gaps were $111{\mu}m$ at cavity margins, $168{\mu}m$ at vertical walls of cavities, $225{\mu}m$ at internal line angles and $123{\mu}m$ at cavity floors.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.2
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• pp.149-159
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• 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
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• v.38 no.1
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• pp.9-17
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• 2022

Purpose: The purpose of this study is to investigate how open contacts impact the natural teeth and dental implant prostheses. Materials and Methods: Following criteria were used to select 20 implant crowns with open proximal contacts as the experimental group (Group A): the restorations were delivered in Chosun University Dental Hospital between 2008 and 2018, the restorations are in the posterior region, opposing teeth are fixed dental prostheses, neighboring teeth are sound natural teeth, the patient had been on the maintenance program for at least 3 years. Another 20 implant crowns with closed proximal contacts were selected as the control group (Group B) using the same criteria. Between the two groups, dental caries and food impaction of the neighboring natural teeth and marginal bone-loss of the implants were compared and evaluated. Results: There was no statistically significant difference between Group A and Group B in the occurrence rates of dental caries, food impaction, and marginal bone-loss. The amount of marginal bone-loss, however, revealed statistically significant differences between the two groups, with Group A showing 0.80 ± 0.39 mm loss and Group B showing 1.1 ± 0.43 mm loss. Conclusion: Implant prostheses with open contacts could be clinically considered in select cases as such restorations revealed no harmful effects on neighboring teeth and implant restorations within the perimeters of this study.