• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.463-476
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• 2010

Inadequate or unstable posterior support cause extrusion of antagonistic teeth and overloading of remaining teeth. Extrusion of antagonistic teeth result in collapsed occlusal plane and decreased prosthetic space. Also, overloading of remaining teeth increase occlusal wear or anterior extrusion of anterior teeth, which is resulting in loss of anterior guidance, disharmony of occlusion and decreased prosthetic space. In this case, careful evaluation of OVD(occlusal vertical dimension) is the general first trial to regain appropriate function and esthetics. Simultaneously, adequate anterior guidance and harmonious occlusal plane should be established in the repeatable reference position of the mandible. We report this case because severely worn dentition achieved functional and esthetic results from full mouth rehabilitation with increased vertical dimension and use of centric relation.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.477-482
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• 2010

In a case of multiple posterior teeth loss, antagonistic teeth extrude to the edentulous space and compensatory occlusion on the remained anterior teeth leads to occlusal trauma. Extrusion of antagonistic teeth breaks down occlusion plane and loss of posterior support bring about severe wear of remained teeth. In this situation, it is needed to restore remained teeth and edentulous space by increasing vertical dimension to obtain prosthodontic rehabilitation space and to correct occlusion plane. In this case report, the patient had a masticatory problem with loss of posterior teeth support and an esthetic problem of shortened anterior teeth. Before the tooth preparation for the prosthodontic restoration, the patient used removable device for 2 months to increase vertical dimension reversibly. After that, he got provisional fixed restoration with irreversible tooth reduction and used it for 3 months. It had spent 5 month to evaluate the adaptation state on final restoration with incresed vertical dimension. The increasing amount was 3 mm, which was relatively in less degree and masticatory system adapted to the increased vertical dimension without any pathologic changes. Final restoration was made to have equal-intensity contacts on all teeth in a verifiable centric relations and immediate disclusion of all posterior contacts the moment the mandible moves in any direction from centric relation. In addition, metal occlusion surface on posterior teeth was applied to prevent excessive muscle activation, occlusal trauma and the porcelain fracture.

• Tribology and Lubricants
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• v.15 no.2
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• pp.164-170
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• 1999

Gerotor is widely used as a hydraulic pump or motor, by virtue of its volume changing ability. Performance deterioration of a gerotor hydraulic motor mainly due to the wear come from the contact between inner rotor with trochoidal curve and outer rotor with circular arc profile. This research covers the basic investigation about the contact forces of a gerotor hydraulic motor using analytic method. The influence of the eccentricity and the radius of circular arc teeth on the contact stress was evaluated.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.3
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• pp.224-233
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• 2024

The patient was a 69-year-old male who had decreased VDO and overbite of the anterior teeth due to severe teeth wear. Complete mouth rehabilitation was planned to restore esthetics and function. Due to the presence of a subgingival finish line, poor fit of the margin of the temporary crown, and insufficient oral hygiene management, gingival overgrowth and bleeding occurred in many teeth, and inaccurate impressions were taken. After dividing each arch and taking partial impressions, a transfer coping was made using pattern resin on each working model die, and after being placed on the abutment teeth, a master cast was made through pick-up impression taking to produce prosthesis. In this case, the final prosthesis produced on the second master cast were fitted in terms of proximal contact, marginal fit, vertical occlusal dimension, facial appearance, esthetics, and occlusion. After complete mouth rehabilitation, the patient was satisfied with function and esthetic appearance.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.93-100
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• 2018

PURPOSE. The purpose of this study was to determine the changing frequency of a diamond bur after multiple usages on 3 different surfaces. MATERIALS AND METHODS. Human premolar teeth (N = 26), disc shaped direct metal laser sintered CoCr (N = 3) and zirconia specimens (N = 3) were used in this study. Groups named basically as Group T for teeth, Group M for CoCr, and Group Z for zirconia. Round tapered black-band diamond bur was used. The specimens were randomly divided into three groups and placed with a special assembly onto the surveyor. 1, 5, and 10 preparation protocols were performed to the first, second, and third sub-groups, respectively. The subgroups were named according to preparation numbers (1, 5, 10). The mentioned bur of each group was then used at another horizontal preparation on a new tooth sample. The same procedure was used for CoCr and zirconia disc specimens. All of the bur surfaces were evaluated using roughness analysis. Then, horizontal tooth preparation surfaces were examined under both stereomicroscope and SEM. The depth maps of tooth surfaces were also obtained from digital stereomicroscopic images. The results were statistically analyzed using One-Way ANOVA, and the Tukey HSD post-hoc tests (${\alpha}=.05$). RESULTS. All of the groups were significantly different from the control group (P<.001). There was no significant difference between groups Z5 and Z10 (P=.928). Significant differences were found among groups T5, M5, and Z5 (P<.001). CONCLUSION. Diamond burs wear after multiple use and they should be changed after 5 teeth preparations at most. A diamond bur should not be used for teeth preparation after try-in procedures of metal or zirconia substructures.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.300-307
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• 2018

PURPOSE. To investigate the fatigue and fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic molar crowns on dental implants and human teeth. MATERIALS AND METHODS. Molar crowns (n=48; n=8/group) were fabricated of a lithium-disilicate-strengthened lithium aluminosilicate glass ceramic (N). Surfaces were polished (P) or glazed (G). Crowns were tested on human teeth (T) and implant-abutment analogues (I) simulating a chairside (C, crown bonded to abutment) or labside (L, screw channel) procedure for implant groups. Polished/glazed lithium disilicate (E) crowns (n=16) served as reference. Combined thermal cycling and mechanical loading (TC: $3000{\times}5^{\circ}C/3000{\times}55^{\circ}C$; ML: $1.2{\time}10^6$ cycles, 50 N) with antagonistic human molars (groups T) and steatite spheres (groups I) was performed under a chewing simulator. TCML crowns were then analyzed for failures (optical microscopy, SEM) and fracture force was determined. Data were statistically analyzed (Kolmogorow-Smirnov, one-way-ANOVA, post-hoc Bonferroni, ${\alpha}=.05$). RESULTS. All crowns survived TCML and showed small traces of wear. In human teeth groups, fracture forces of N crowns varied between $1214{\pm}293N$ (NPT) and $1324{\pm}498N$ (NGT), differing significantly ($P{\leq}.003$) from the polished reference EPT ($2044{\pm}302N$). Fracture forces in implant groups varied between $934{\pm}154N$ (NGI_L) and $1782{\pm}153N$ (NPI_C), providing higher values for the respective chairside crowns. Differences between polishing and glazing were not significant ($P{\geq}.066$) between crowns of identical materials and abutment support. CONCLUSION. Fracture resistance was influenced by the ceramic material, and partly by the tooth or implant situation and the clinical procedure (chairside/labside). Type of surface finish (polishing/glazing) had no significant influence. Clinical survival of the new glass ceramic may be comparable to lithium disilicate.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.3
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• pp.146-157
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• 2023

The bite collapses due to posterior teeth loss or wear results in inadequate space for restoration and esthetic concerns. Increasing the occlusal vertical dimension to improve space deficiency rotates the mandible posteriorly, creating a gap between the maxillary and mandibular anterior teeth, leading to loss of anterior guidance. To solve this problem, the prosthodontics or orthodontics treatments are the commonly used methods for proper anterior guidance. However, it is reasonable to assume that the anterior teeth can naturally relapse to their original position when the occlusal force is eliminated. Therefore, this case report aimed to test whether natural relapse could recover the lost anterior guidance to develop a less invasive and more convenient treatment method. Digital superimposition was used to evaluate the changes in anterior teeth alignment to confirm the change of the recovered anterior guidance. The appropriate indications for this new treatment method were defined and applied clinically.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.171-179
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• 2017

Severely worn dentition is frequently multifactorial. It is crucial that the etiology of excessive wear be determined, but accurately diagnosing the factors responsible for tooth wear is often confusing. Before initiating the treatment of these cases, meticulous examination and determining vertical dimension are essential. A 69-year-old male patient had the chief complaint that he has worn dentition and functional and esthetic discomfort. Based on model analysis and diagnostic wax up, new vertical dimension had been determined. Provisional restorations were cemented and after 5 months permanent prostheses were fabricated. This case reports a satisfactory functional and esthetic clinical outcome achieved by restoring the vertical dimension.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.31-39
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• 2018

The collapse of the posterior occlusion destroys the normal occlusal plane and causes excessive wear reducing the vertical dimension. Reduced vertical dimension of occlusion causes not only aesthetic and functional problems but also overloading on the temporomandibular joints and abnormalities of muscle nerve system. In order to improve the collapsed occlusal relationship, it is necessary to consider the change of the vertical dimension. It is necessary to make a precise diagnosis and analysis before the treatment and to evaluate the adaption of patient to the new vertical dimension of occlusion. A patient with excessive overbite often has occlusal problems of tooth wear and tooth eruption. Considering these considerations, overall prosthodontic restoration is required to solve the problem. A patient of 68 year old man in this case who suffered major tooth wear and maxillary posterior teeth loss was treated with elevation of vertical dimension of occlusion by maxillary removable dental prosthesis and mandibular fixed prosthesis.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.3 no.1
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• pp.1-5
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• 2007

Patients of mental disorder have more missing teeth than general population because of the difficulty of oral hygiene management. In addition, especially Down syndrome patients etc., congenital dental problems develop more frequently. Therefore, prosthetic rehabilitation treatments for missing teeth in mental disorder patients are required more urgently. In other words, a removable partial denture may be very difficult for such patients to wear and manage. So in this review article we reviewed implant therapeutic modes for mental disorder patients based on previous reports. It should be understood that implant treatments are not impossible for mental disorder patients, and if implants could be a good method that could provide them good quality care, so implant should be included in treatment plans before surgery. Before surgery it should be evaluated that patients ability to manage themselves their ability to manage themselves should be evaluated and also should be evaluated whether general anesthesia or sedative treatment is required for the treatment, and whether their cooperation is good enough.