• Journal of International Society for Simulation Surgery
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• v.2 no.1
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• pp.1-6
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• 2015

Purpose Bisphophonate-related osteonecrosis of the jaw (BRONJ) is an emerging problem. Extensive osteonecrosis of the jaw needs free flap reconstruction. Free fibular flap is the most useful flap for maxilla-mandibular hard and soft tissue reconstruction. The advantages of fibular free flap are simultaneous soft and hard tissue reconstruction and placing implant in reconstructed mandible and maxilla. In this study, four consecutive BRONJ patients who underwent fibula free flap reconstruction using simulation surgery were reviewed. Materials and Methods Four BRONJ patients who underwent free fibula reconstruction between May 2006 and September 2014 were included in this study. Male to female ratio was 1:3 and average age was 67.3 years old (62-70). All patients need mandibular bone reconstruction. Three patients suffered from osteoporosis and one male patient had multiple myeloma. Postoperative flap survival, functional reconstruction, esthetic results, food taking were evaluated. Results Three osseous flaps and one osteocutaneous flap were used. All the fibular flaps were survived and patients were recovered without complications. Oro-cutaneous fistula was resolved after operation. All patients were satisfied with the esthetic results. Patients reported improved solid food intake after operation with partial denture. One fully edentulous patient had semi-fluid diet after operation. Conclusion Treatment of the BRONJ is difficult due to lack of standard protocol. Fibular free flap using simulation surgery is the workhorse flap for mandibular hard and soft tissue reconstruction, especially in stage III BRONJ patient. In this study, functional and esthetic results were successful in all patients. Normal diet was possible with partial dentures.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.354-361
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• 2011

There are still many limitations on fabricating dentures using digital method while computerized production of fixed prostheses utilizing intraoral scanner and CAD/CAM technology has propagated rapidly. Recently the digital solution of fabricating removable partial denture by applying haptic input device, electronic surveying, and rapid prototyping was introduced. In this case presentation, five patients were treated with surveyed crown and removable partial dentures by this digital solution. Fit of dentures was excellent except for one case which showed morphological difference between the actual teeth and that of master cast by the erroneous impression process. There also was not any problem of stability and retention after adaptation in the clinical setting.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.118-125
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• 2013

PURPOSE. The purpose of this study was to evaluate the effect of the span length on the fit of zirconia framework fabricated using CAD/CAM system. MATERIALS AND METHODS. Abutments for single, 4-unit and 6-unit fixed partial prostheses were fabricated. Ten zirconia frameworks were fabricated for each group. The marginal and internal gap were presented by means of replica technique and measured by measuring microscope ($AXIO^{(R)}$, Carl Zeiss, Rochester, NY) and software (I-$solution^{(R)}$, IMT i-solution Inc., Vancouver, BC, Canada). The results were statistically analyzed by multivariate analysis test and Dunnett T3 test for post hoc test (${\alpha}$=.05). RESULTS. There were statistically significant differences at 2, 4, 7, 8 points (mesio-distal section) and b, d, e, f, g (labio-lingual section). In some marginal reference points of 6-unit group (P<.05), the marginal gap were larger than 120 ${\mu}m$. CONCLUSION. Span length of zirconia core may have an influence on marginal and internal fit. Within the limitation of this study, the increase of span length of zirconia framework of 6 or more-unit fixed partial denture may decrease the marginal and internal fit.

• The Journal of Advanced Prosthodontics
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• v.13 no.5
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• pp.304-315
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• 2021

PURPOSE. Esthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue. MATERIALS AND METHODS. PEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05). RESULTS. The retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively). CONCLUSION. Thermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.354-361
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• 2022

The development of digital technology is causing great changes in dentistry. This digital workflow combines various 3D data in the prosthetic treatment area for diagnosis and prosthetic manufacturing. The planned diagnosis and the fabrication of prosthesis in a virtual patient formed by synthesizing digital data can simulate the results of prosthetic treatment more intuitively than conventional methods, thereby increasing the predictability of aesthetic prosthetic treatment. In this case report, functionally and aesthetically satisfied clinical results were obtained by fabricating a fixed partial dentures through a digital workflow on congenital missing teeth in the maxillary anterior region.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.85-90
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• 2009

STATEMENT OF PROBLEM. Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE. The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS. Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS. Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P <.05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P>.05). Group V had the highest mean MPa (N/$mm^2$) (P <.05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION. Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P>.05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P<.05).

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.5
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• pp.429-440
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• 2002

Current dental restorations present a relatively weak resistance to fracture. Owing to their unique mechanical properties, fibre-reinforced polymers are now being considered. Unidirectional or woven continuous fibres, made of glass, polyethylene, carbon or Kevlar, have been evaluated. This study focused on the use of glass fibre knitted fabrics to reinforce acrylate resins, in order to investigate the possibility to construct single crowns as well as three unit bridges. Some points affecting the final composite system were tested ; 1) static strength, with focus on the stress transfer under a occlusal contact point ; 2) modelling of a three nit bridge ; 3) fatigue strength as a posterior three unit bridge material. The study demonstrated that knitted fabric reinforcements are showing an interesting compromise between stiffness, static strength for single crown. For three unit bridge applications in the posterior arch, however knitted glass fabric reinforcements were not strong enough in fatigue An additional reinforcement in the posterior arch fixed partial denture design was recommended.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.4
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• pp.301-307
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• 2006

The subgingival fracture near the alveolar bone is difficult to treat. This fractured tooth will be treated by many methods. First approach is to preserve the fractured tooth. Periodontal surgery has been used to lengthen the clinical crown, thereby allowing the tooth to be restored. Another method is erupting the tooth with orthodontic eruption (forced eruption) or surgical extrusion. Second approach is the restoration after extraction of the subgingivally fractured tooth. This is restorative with conventional fixed partial denture or implant. This article presents the variable restorative approach of subgingivally fractured upper incisor.

• Journal of the korean academy of Pediatric Dentistry
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• v.7 no.1
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• pp.41-45
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• 1980

The term "Oligodontia" or "Hypodontia" have been used to describe variable degrees of reduction in number of teeth. Oligodontia may occur alone or as a result of some syndrome. Although the teeth are derived in part from ectoderm, the current opinion of reason of oligodontia should be reserved for those disorders in which there is abnormal development of one or more ectodermal tissues. 7 year 5 months old female was refered to the department of pedodontics, college of dentistry Yonsei university for evaluation and replacement of absent teeth. She had no special inf.ectious disease in her childhood, and her parents were healthy. She had no special syndrome of ectodermal disorders except the saddle nose, yellow and fine hair, and notched upper anterior central incisor. Panex radiogram was showing 6 anterior primary teeth, 2 permanent first molars and 2 unerupted first bicuspid in mandible. Another permanent teeth were absent. and normal number of primary and permanent teeth in maxilla. Lateral cephalogram showed no special abnormality in growth pattern. We had evaluated lower anterior decayed teeth with jacket resin and chrome steel crown and removable partial denture at missing area. We had got good results for rehabilitation of function and aesthetic.