Interproximal contact loss between implant-supported prostheses: a clinical report / 대한치과보철학회지

Interproximal contact loss (ICL) is the most frequent complication in partially edentulous patients treated with implant-supported prostheses. However, in most cases, ICL occurs between the implant prosthesis and the natural tooth due to the movement of the natural tooth. There are several causes of ICL that occur between an implant prosthesis and a natural tooth. There are only a few reported cases of ICL occurring between implant prostheses, and explaining the causes of ICL between implant prostheses and natural teeth is challenging. This clinical report describes cases of ICL between implant prostheses and discusses its causes and countermeasures.

Aesthetic restoration using liner-treated lithium disilicate laminate veneers in discolored teeth after endodontic treatment : A case report / 대한치과재료학회지

Improvements in the mechanical and optical properties of ceramic materials and the development of dentin adhesives have resulted in more successful results in anterior teeth restorations. Among them, porcelain laminate veneer (PLV) can achieve aesthetic improvement in a conservative way while minimizing tooth reduction. A female patient in her 20s visited for aesthetic improvement of the maxillary anterior teeth. The patient's chief complaint was aesthetic improvement of tooth discoloration after trauma and endodontic treatment, and a PLV restoration was decided to reflect the patient’s demand for minimal tooth reduction. IPS e.max Press, a lithium disilicate-based ceramic with high light transmittance and high strength, was chosen for porcelain laminate veneer. Inner surface of the veneer was treated with liner in order to block discoloration of the abutment teeth while maintaining translucency in the incisal edge. The patient was satisfied with the aesthetic result.

Aesthetic restoration of maxillary central incisor with discoloration using lithium disilicate treated with liner: A case report / 대한치과재료학회지

Lithium disilicate gradation block that have been recently introduced and used in dental clinics have superior light transmittance compared to zirconia-based restorations, so that when applied to anterior restorations, better esthetic results are expected. In addition, it has the advantage that the flexural strength is sufficient and chemical bonding with resin cement is possible. However, high transparency could be a disadvantage in the restoration of abutment teeth with severe discoloration, and various methods have been tried to compensate for this. In this study, in the restoration of central incisors with severe discoloration of the abutment, the inner surface of the crown made of lithium disilicate-based polychromatic blocks was treated with a liner to block the discoloration, and thus aesthetically satisfactory results were obtained.

Rehabilitation with orthognathic surgery and orthodontic treatment in patient with severe occlusal disharmony:A case report / 대한치과보철학회지

The occlusal treatment including prosthetic treatment should be considered when the pathologic symptom was observed with the excessive discrepancy between the centric relation occlusion (CRO) and the maximum intercuspal position (MIP). Through careful diagnosis, the malocclusion and interarch relationship can be analyzed, and occlusal adjustment, restorative treatment, orthodontic therapy, or orthognathic surgery can be performed depending on the degree of disharmony. The patient in this case report complained the unstable occlusion and loss of masticatory function that had been occurring for several years. At the time of the visit, the patient showed severe occlusal disharmony, with only the upper right second molar contacting the lower jaw at the maximum intercuspal position. Based on the analysis of the occlusion, it was difficult to solve the problem with just occlusal adjustment or restorative treatment. In addition, the patient had the skeletal class II malocclusion between the upper and lower jaws. Therefore, for resolving the severe skeletal class II malocclusion, pre- and post-orthodontic treatment, bilateral sagittal split ramus osteotomy (BSSRO) was performed. After that, the occlusal adjustment was performed for stable occlusion, and the missing teeth area was restored with dental implants. During the follow-up period, a periodic follow-up visits and additional occlusal adjustments were performed to achieve a stable centric occlusion and harmonious anterior and lateral guidance. As a result, the final prosthodontic treatment was completed, and the patient’s masticatory function was restored.

A comparative study of impression methods using stock tray and intraoral scanner in a completely edentulous / 대한치과보철학회지

In complete denture fabrication, accurate preliminary impressions are crucial for obtaining an accurate final impression. However, it can be challenging in cases of atypical arch shapes. This case report compares diagnostic casts made with a stock tray and an intraoral scanner (IOS) in a patient with an atypical arch shape.A 58-year-old edentulous male patient with long, narrow, atypical arches was referred to the Oral and Maxillofacial Surgery department for complete denture fabrication. Compared to the diagnostic cast obtained using IOS with adequately captured anatomical parameters, the primary model obtained using a stock tray showed prominent overextended flanges on the labial and buccal sides of the maxillary arch and less prominent overextended flanges in the mandibular arch with pressure spots in the posterior palatal seal area. The custom tray fabricated from such a model required additional adjustment resulting in increased chair time during the final impression procedure.

Occlusal rehabilitation of post-traumatic malocclusion patient after reduction of panfacial fracture, using selective occlusal adjustment and implant prostheses on centric relation: a case report

Invasive or non-invasive reduction of fractures could be conducted as treatments of traumatic maxillofacial bone fractures.But when suboptimal reduction or malunion of maxillofacial bone fracture occurs, malocclusion could occur as a result of the lost relationship of the mandible and midface. This malocclusion is called post-traumatic malocclusion and orthognathic surgery, orthodontic treatment, selective grinding and prosthetic reconstruction are suggested as treatments for post-traumatic malocclusion after securement of stable TMJ. Stable TMJ is essential for occlusal rehabilitation to prevent occlusal change and relapse of malocclusion. Centric relation and adapted centric posture are suggested as start points of occlusal rehabilitation because they are most stable TMJ position. This case report presents a case in which post-traumatic malocclusion occurred after reduction of panfacial fracture. To rehabilitate full mouth occlusion, selective grinding and prosthetic reconstruction of implant supported fixed prostheses were conducted in centric relation and showed satisfying results in functional and occlusal aspects.

Effect of abutment neck taper and cement types on the amount of remnant cement in cement-retained implant restorations:an in vitro study

PURPOSE@#The present study aims to analyze the effect of abutment neck taper and types of cement on the amount of undetected remnant cement of cement-retained implant prostheses. @*MATERIALS AND METHODS@#Three neck taper angles (53°, 65°, 77°) and three types of cement (RMGI: resin-modified glass ionomer, ZPC: zinc phosphate cement, ZOE: zinc oxide eugenol cement) were used. For each group, the surface percentage was measured using digital image and graphic editing software. The weight of before and after removing remnant cement from the abutment-crown assembly was measured using an electronic scale. Two-way ANOVA and Duncan & Scheffe’s test were used to compare the calculated surface percentage and weight of remnant cement (α = .05). @*RESULTS@#There were significant differences in remnant cement surface percentage and weight according to neck taper angles (P .05). The wide abutment with a small neck taper angle showed the most significant amount of remnant cement. And the types of luting cement did not influence the amount of residual cement. @*CONCLUSION@#To remove excess cement better, the emergence profile of the crown should be straight to the neck taper of the abutment in cement-retained implant restoration.

Prosthetic rehabilitation by obturator considering the biomechanics in partially edentulous patient after maxillectomy

Patients who went through maxillectomy can have severely impaired swallowing, mastication, and pronunciation functions because of palatal defects. Leakage occurs through the nasal cavity while eating, chewing becomes difficult due to the loss of teeth and alveolar ridges, and oral and nasal passages are not separated, leading to hyper-nasal sound, and significantly reducing the quality of life. To prosthetically reconstruct the defect, the weight of the obturator should be reduced as much as possible to minimize dropout because of gravity, and the bulb of the obturator should be properly extended into the defect to get additional retention and stability. In this case of a partially edentulous patient who underwent additional maxillary resection because of tumor recurrence, a metal framework was designed by applying the basic design principles of removable partial dentures. An obturator with improved retention, stability, and support was fabricated through functional impressions. The patient was satisfied with the improved facial expression, mastication, swallowing, and pronunciation, and showed stable occlusion and oral hygiene management during the follow-up period.

Esthetic considerations for anterior implant-supported prostheses:focus on surgical and prosthetic treatment

As the increased certainty of osseointegration, new parameters are now being used to assess implant success. Accordingly, patients’ and clinicians’ high demands and expectation for esthetics have expanded and implant-supported restorations show better esthetic outcomes. The pre-implant treatment planning process, the implant surgical steps and the post-surgery prosthetic process can affect all esthetic outcomes. Prevention of esthetic implant failures can be achieved by appropriate treatment at each stage, considering the 3 factors of alveolar bone, soft tissue, and implants. It is necessary to achieve the esthetic implant prostheses followings: minimal invasive surgery, bone augmentation, ideal 3-dimensional implant position, peri-implant soft tissue management, and provisional restorations to optimize peri-implant soft tissue architecture.

Full-mouth rehabilitation with increasing minimum vertical dimension in the patient with severely worn dentition and deep bite / 대한치과보철학회지

Full-mouth rehabilitation with increasing vertical dimension can be used for patients with severely worn teeth. In severely worn teeth also, the alveolar process can be elongated to compensate for the reduced vertical dimension, and the patient’s vertical dimension of occlusion can be kept constant. However, full-mouth rehabilitation with increasing vertical dimension must be carefully chosen, because the vertical dimension can be reduced by tooth wear. It is important to establish a treatment plan with the systematic diagnosis of the change in the vertical dimension and gain space for the prosthesis. It is necessary to change the vertical dimension to secure the restoration space and select the minimum vertical dimension elevation for the esthetic and functional goal. In this case report, the patient complained of difficulty during chewing due to a worn dentition and wanted esthetic improvement of the short mandibular anterior teeth. After systematic evaluation and diagnosis, we performed full-mouth rehabilitation with minimum vertical dimension elevation to obtain the space for restoration. This resulted in a stable and harmonious occlusion, and the functional and esthetic problems of the patient were solved after treatment. The patient was satisfied with the results of the treatment and maintained stable occlusion during the follow-up period.

Application of various digital technique on full mouth rehabilitation: A case report / 대한치과보철학회지

Based on rapid improvement in digital fields, many advanced digital technologies are utilized in prosthodontic treatment. Especially, intraoral scanners and 3D printing technology are commonly used, and facial scanning technology is recently being attempted to be part of these digital routines. This case report aims to introduce a digital procedure using the intraoral scanner, facial scanner, and 3D printing technology to create definitive restorations, which are esthetic and harmonious with patient’s face. From thoroughly evaluated full-mouth provisional restoration which was manufactured and fitted conventionally, definitive prostheses were fabricated using various digital technique. Stable occlusion with functionally and aesthetically satisfying results were achieved.

The Effect of N-acetyl cysteine (NAC) loading on the bone formation surrounding sandblastedand large-grit and acid-etched implants in the dog: A pilot study / 대한치과보철학회지

The aim of the present study was to investigate the effects of N-acetyl cysteine (NAC) loading on the bone formation surrounding sandblasted, large-grit and acidetched(SLA) implants. Materials and methods: Implantation of NAC loaded SLA implants (NSI group) and SLA implants (SI group) was performed bilaterally in themandible of 4 adult beagle dogs (each group, n = 8). The animals were sacrificed after a healing period of 3 and 6 weeks, respectively (n = 2 animal each). Dissected blockswere processed for histomorphometrical analysis. Bone to implant contact percentage (BIC%) and bone volume (BV%) were assessed histomorphometrically. Results:BIC% of NAC loaded SLA implants were about 50% higher than that of SLA implants at 3 weeks of bone healing, but not significantly (51.79 vs 35.43%; P=.185). BV% ofNAC loaded SLA implants were significantly higher than that of SLA implants at 3 weeks of bone healing (45.09 vs 37.57 %; P=.044). At 6 weeks of bone healing, BIC%and BV% of two experimental groups were similar (P>.05). Conclusion: Within the limits of the present study, NAC loading have a positive effects on the early bone formationsurrounding SLA implants. So, it might be concluded that NAC loading enhance the osseointegration and shorten the healing time after implantation of the SLAimplants. (J Korean Acad Prosthodont 2020;58:77-85)

Effect of attachments and palatal coverage of maxillary implant overdenture on stress distribution: a finite element analysis

Purpose@#The purpose of this study was to evaluate the effect of attachments and palatal coverage on stress distribution in maxillary implant overdenture using finite element analysis. @*Materials and Methods@#Four maxillary overdenture 3-D models with four implants placed in the anterior region were fabricated with computer-aided design. 1) Ball-F: Non-splinted ball attachment and full palatal coverage, 2) Ball-P: Non-splinted ball attachment and U-shaped partial palatal coverage, 3) Bar-F: Splinted milled bar attachment and full palatal coverage, 4) Bar-P: Splinted milled bar attachment and U-shaped partial palatal coverage. Stress distribution analysis was performed with ANSYS workbench 14. 100 N vertical load was applied at the right first molar unilaterally and maximum stress was calculated at the implant, peri-implant bone and mucosa. @*Results@#The use of the ball attachment showed lower maximum stress on implant and peri-implant bone than the use of the milled bar attachment. But it showed contrary tendency in the mucosa. Regardless of attachment, full palatal coverage showed lower maximum stress on implant, peri-implant bone and mucosa. @*Conclusion@#Within the limitation of this study, ball attachment improved stress distribution on implant and periimplant bone rather than milled bar attachment in maxillary implant overdenture. Also, full palatal coverage is more favorable in stress distribution.

Full mouth rehabilitation in patient with loss of vertical dimension and deep bite due to tooth wear / 대한치과보철학회지

Excessive tooth wear can cause irreversible damage to the occlusal surface and can alter the anterior occlusal relationship by destroying the structure of the anterior teeth needed for esthetics and proper anterior guidance. The anterior deep bite is not a morbid occlusion by itself, but it may cause problems such as soft tissue trauma, opposing tooth eruption, tooth wear, and occlusal trauma if there are no stable occlusal contacts between the lower incisal edge against its upper lingual surface. The most important goal of treatment is to form stable occlusal contact in centric relation. In this case report, patients with decrease in vertical dimension and anterior deep bite due to maxillary posterior tooth loss and excessive tooth wear were treated full mouth rehabilitation with increased vertical dimension to regain the space for restoration and improve anterior occlusal relationship and esthetics. The functional and aesthetic problems of the patient could be solved by the equal intensity contact of all the teeth in centic relation (CR), anterior guidance in harmony with the functional movement, and restoration of the wear surface beyond the enamel range.

Retrospective study on survival, success rate and complication of implant-supported fixed prosthesis according to the materials in the posterior area / 대한치과보철학회지

PURPOSE: The purpose of this study was to retrospectively investigate the survival and success rate of implant-supported fixed prosthesis according to the materials in the posterior area. Other purposes were to observe the complications and evaluate the factors affecting failure. MATERIALS AND METHODS: Patients who had been restored implant prosthesis in the posterior area by the same prosthodontist in the department of prosthodontics, dental hospital, Chonbuk National University, in the period from January 2011 to June 2018 were selected for the study. The patient's sex, age, material, location, type of prosthesis and complications were examined using medical records. The Kaplan-Meier method was used to analyze the survival and success rate. The Log-rank test was conducted to compare the differences between the groups. Cox proportional hazards model was used to assess the association between potential risk factors and success rate. RESULTS: A total of 364 implants were observed in 245 patients, with an average follow-up of 17.1 months. A total of 5 implant prostheses failed and were removed, and the 3 and 5 year cumulative survival rate of all implant prostheses were 97.5 and 91.0, respectively. The 3 and 5 year cumulative success rate of all implant prostheses were 61.1% and 32.9%, respectively. Material, sex, age, location and type of prosthesis did not affect success rate (P>.05). Complications occurred in the order of proximal contact loss (53 cases), retention loss (17 cases), peri-implant mucositis (12 cases), infraocclusion (4 cases) and so on. CONCLUSION: Considering a high cumulative survival rate of implant-supported fixed prostheses, regardless of the materials, implant restored in posterior area can be considered as a reliable treatment to tooth replacement. However, regular inspections and, if necessary, repairs and adjustments are very important because of the frequent occurrence of complications

Full mouth rehabilitation of fully edentulous patient with implant-supported fixed prosthesis preceding bone graft: A case report / 대한치과보철학회지

Prosthetic treatment using implants in fully edentulous patients includes implant-supported fixed prosthesis, implant hybrid prosthesis, implant retained- or supported-overdenture and implant supported fixed prosthesis has advantages such as psychological stability, pronunciation. If an implant supported fixed prosthesis is planned, the implants should be placed in consideration of pronunciation, esthetics, and oral hygiene. For this, clinical and radiological diagnosis is indispensable. When placing the prosthetic driven implant at the site determined from the diagnosis, a sufficient amount of alveolar bone and soft tissue support are required. If these requirements found to be insufficient, a wide range of bone grafting should be performed in advance. In this case, a fully edentulous patient with severe alveolar bone resorption due to periodontal disease was treated with a full mouth rehabilitation using implant-supported fixed prosthesis preceding maxillary sinus graft and alveolar bone augmentation. We report this patient were satisfied with esthetic and function.

Three-year follow-up of full mouth rehabilitation with anterior implant surveyed bridges and distal extension removable partial denture / 대한치과보철학회지

In partial edentulous patients, implant-assisted removable partial denture which provide additional retention and support by placing a small number of implants in strategic positions might be suitable treatment. This case of patient with loss of maxillary posterior teeth and moderate to severe wear of residual dentition, three implants were placed in the maxillary anterior edentulous area and then surveyed bridges were made including remaining anterior natural teeth. Posterior edentulous area was restored with distal extension removable partial denture (RPD). In addition, the worn mandibular natural teeth were restored with fixed prostheses. As a result, reduced vertical dimension and collapsed occlusal plane were rehabilitated, and improved functionally and aesthetically. The purpose of this case was to report the results of three-year follow-up of full mouth rehabilitation with anterior implant surveyed bridges and distal extension RPD.

The effect of heat to remove cement on implant titanium abutment and screw / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. MATERIALS AND METHODS: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to 450℃ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. RESULTS: The mean removal torque value was 27.84 ± 1.07 Ncm in the control group and 26.55 ± 1.56 Ncm in the experimental group and showed statistically significant difference (P .05). CONCLUSION: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

Strategic serial extractions and immediate implantation for interdental papilla preservation: A case report / 대한치과보철학회지

Maintaining the blood supply of the interdental alveolar bone is crucial for preserving the interdental papilla. Rebuilding the interimplant papilla between adjacent implants is more difficult than rebuilding the interdental papilla between the natural tooth and implant. Therefore, preserving the interimplant tissue is necessary when adjacent implants are closely placed. In this case report, three effective methods for maintaining the surrounding tissue, namely strategic serial extraction, immediate implantation, and provisionalization of adjacent maxillary central incisors, were performed. The marginal gingiva and interimplant papilla were well maintained for 24 months.

Influence of nano-structured alumina coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements

PURPOSE: The purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements. MATERIALS AND METHODS: A total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength (P<.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used. RESULTS: Groups treated with the nanostructured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating. CONCLUSION: Nano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured resin cements.