Full mouth rehabilitation with fixed prostheses by increased vertical occlusal dimension using 3D printed splint in a patient with excessive tooth wear / 대한치과보철학회지

Severe wear of the anterior teeth facilitates the loss of anterior guidance, which protects the posterior teeth from wear during excursive movement. Additionally, when treating patients with collapsed occlusion due to multiple tooth loss and tooth wear, it is important to determine the presence of vertical dimension loss through accurate clinical and radiographic examinations and diagnostic wax-up. The patient of this case is a 44-year-old female patient who complained of overall tooth wear and loss of posterior teeth due to bruxism and clenching habits, visited the hospital with the address of restoring masticatory function and improving aesthetic appearance through prosthetic treatment. Through model analysis and diagnostic wax-up, an increase in vertical dimension was determined, and full mouth restoration with fixed prostheses was planned. The degree of adaptation to the vertical dimension was confirmed step by step using an occlusal splint designed with CAD (Computer aided design) software and 3-D (3-Dimensional) printed, and then restored with provisional restoration and after a 4-month adaptation period, the entire dentition was restored with metal ceramic crowns and implants. Through this procedure, satisfactory treatment results were obtained in terms of function and aesthetics.

Creation of the dental virtual patients with dynamic occlusion and its application in esthetic dentistry / 대한치과보철학회지

Digital technology is gradually expanding its field and has a great influence on various fields of dentistry. Recently in digital dentistry, the importance of superimposing various 3-dimensional (3D) image data is emerging, in order to utilize gathered data effectively for diagnosis and prosthesis fabrication. Integrating data from facial scans, intraoral scans, and mandibular movement recordings can create a virtual patient. A virtual patient is formed by integrating digital 3D diagnostic data such as intraoral and extraoral soft tissues, residual dentition, and dynamic occlusion, and the results of prosthetic treatment can be evaluated virtually. The patients in this case report were a 37-year-old female whose chief complaint is that the appearance of the existing prosthesis was distorted and a 55-year-old female patient whose anterior prosthesis needed to be refabricated after the endodontic treatment. 3D facial scans were obtained from each patient, and the patient’s mandibular movements were recorded using ARCUS Digma 2 (KaVo Dental GmbH, Biberach an der Riss, Germany). The collected data were integrated on computer-aided design (CAD) software (Exocad dental CAD; exocad GmbH, Darmstadt, Germany) and transferred to a virtual articulator to create a digital virtual patient. The temporary fixed prostheses were designed, restored, and evaluated, and it was reflected into the final restorations. With the aid of the virtual dental patient, accuracy and predictability could be increased throughout treatment, simplifying the occlusal adjustment and clinical evaluation with improved esthetic outcomes.

A study on the shear bond strength between 3D printed resin and provisional resin after thermal cycling

Purpose@#In this study, we intended to study the change in bond strength according to the thermal cycling of provisional resin and 3D printed resin for making provisional restoration. Materials and Methods: Through DLP method, 3D printed resin powder was used to produce 3D printed resin samples. The samples were grouped into eight groups, according to types of provisional resin (PMMA, bis-acryl resin) which is to be bonded on the samples and numbers of thermal cycling (control, 2,000, 3,000, 5,000 cycles). Shear bond strength of the bonded samples was measured on the universal testing machine. @*Results@#As the number of thermal cycling increased, the shear bond strength of PMMA and bis-acryl resin for 3D printed resins decreased except between 3,000 cycles and 5,000 cycles in PMMA groups. In the PMMA group, there were significant differences in shear bond strength between less number than 3,000 cycles (P 0.05). In the bis-acryl resin group, there were significant differences in shear bond strength between control and 2,000 cycles, control and 3,000 cycles, and control and 5,000 cycles (P 0.05). @*Conclusion@#The shear bond strength between 3D printed resin and provisional resin tended to decrease after thermal cycling.

The comparisons of layers and the effect of additional firings on flexural strength and translucency of 5Y-ZP

Purpose@#The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. @*Materials and Methods@#Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900°C using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. Oneway ANOVA, Tukey HSD test were performed (α = 0.05). @*Results@#There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. @*Conclusion@#Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

Cr-Co removable partial denture treatment fabricated by selective laser melting: a case report

Compared to conventional method, if metal framework of removable partial denture is fabricated by selective laser melting, various laboratory works are omitted, saving time and simplifying the process. In addition, metal framework with homogeneous density can be obtained, expecting excellent mechanical properties, especially resistance to fatigue fracture. In these cases, impression were taken using conventional methods in partial edentulous patients, master casts were fabricated and scanned to obtain digital data. After designing the metal frameworks on the scanned data, removable partial dentures were fabricated using selective laser melting methods. Through these procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

Full mouth rehabilitation of iatrogenic attrition patient / 대한치과보철학회지

Physiologic tooth attrition is accepted as a natural change. But when pathologic changes, such as loss of occlusal vertical dimension, masticatory pain, loss of masticatory function, and loss of esthetics occur, restorative measures should be taken by dentist. A patient visited the clinic with the chief complaint of ‘My lower teeth bite the palate and it hurts’. It was diagnosed as iatrogenic attrition of lower natural dentition caused by inappropriate upper restorations, resulting in traumatic overbite. Through model analysis and diagnostic wax up, increase in vertical dimension was decided. Upper and lower dentitions were restored with new prostheses. After restoration, satisfactory outcomes were achieved both in functional and esthetic aspects

Full mouth rehabilitation of iatrogenic attrition patient / 대한치과보철학회지

Physiologic tooth attrition is accepted as a natural change. But when pathologic changes, such as loss of occlusal vertical dimension, masticatory pain, loss of masticatory function, and loss of esthetics occur, restorative measures should be taken by dentist. A patient visited the clinic with the chief complaint of ‘My lower teeth bite the palate and it hurts’. It was diagnosed as iatrogenic attrition of lower natural dentition caused by inappropriate upper restorations, resulting in traumatic overbite. Through model analysis and diagnostic wax up, increase in vertical dimension was decided. Upper and lower dentitions were restored with new prostheses. After restoration, satisfactory outcomes were achieved both in functional and esthetic aspects

Bonding of conventional provisional resin to 3D printed resin: the role of surface treatments and type of repair resins

PURPOSE@#This study evaluated the shear bond strength between 3D printed provisional resin and conventional provisional resin depending on type of conventional provisional resin and different surface treatments of 3D printed resin. @*MATERIALS AND METHODS@#Ninety-six disc-shaped specimens (Ø14 mm × 20 mm thickness) were printed with resin for 3D printing (Nextdent C&B, Vertex-Dental B. V., Soesterberg, Netherlands). After postprocessing, the specimens were randomly divided into 8 groups (n=12) according to two types of conventional repair resin (methylmethacrylate and bis-acryl composite) and four different surface treatments: no additional treatment, air abrasion, soaking in methylmethacrylate (MMA) monomer, and soaking in MMA monomer after air abrasion. After surface treatment, each repair resin was bonded in cylindrical shape using a silicone mold. Specimens were stored in 37°C distilled water for 24 hours. The shear bond strength was measured using a universal testing machine at a crosshead speed of 0.5 mm/min. Failure modes were analyzed by scanning electron microscope. Statistical analysis was done using one-way ANOVA test and Kruskal-Wallis test (α=.05). @*RESULTS@#The group repaired with bis-acryl composite without additional surface treatment showed the highest mean shear bond strength. It was significantly higher than all four groups repaired with methylmethacrylate (P.05). Failure mode analysis showed that cohesive failure was most frequent in both methylmethacrylate and bis-acryl composite groups. @*CONCLUSION@#Our results suggest that when repairing 3D printed provisional restoration with conventional provisional resin, repair with bis-acryl composite without additional surface treatment is recommended.

Study of the fracture resistance of zirconia on posterior fixed partial dentures based on inter-abutment distance

Purpose@#Zirconia fixed partial dentures with mandibular 2nd premolar and 2nd molar as abutments are fabricated and then the effects of inter-abutment distance on fracture resistance of zirconia fixed partial dentures is studied. @*Materials and Methods@#The materials used in this study are Cameleon S zirconia block and S2 zirconia block, which are divided into CS Group and S2 Group applying different inter-abutment distance for each material, and the sintered zirconia fixed partial denture was luted to the epoxy resin die using a temporary luting cement, and then the fracture resistance was measured by placing a 6 mm diameter hardened steel ball on the occlusal surfaces of the pontics and applying pressure at a cross head speed of 1.0 mm/min on a universal testing machine with a load cell of 5.0 kN. @*Results@#The fracture resistance of zirconia fixed partial dentures is not significantly affected by inter-abutment distance The fracture resistance of zirconia fixed partial dentures in CS Group was significantly higher in 15 mm of inter-abutment distance than in 13 mm and 17 mm of inter-abutment distance (P 0.05). @*Conclusion@#The fracture resistance of zirconia fixed partial dentures with mandibular 2nd premolar and 2nd molar as abutments does not significantly affected by the inter-abutment distance.

Comparative study of surface modification on bond strength of polyetherketoneketone adhesively bonded to resins for temporary restoration

Purpose@#The purpose was to compare shear bond strength (SBS) of three types of resin for temporary restoration to polyetherketoneketone (PEKK) depending on surface modification. @*Materials and Methods@#Sixty disks made from PEKK were air-abraded with 110 μm alumina particles (Cobra, Renfert GmbH, Hilzinge, Germany) and thirty specimens were divided into two groups each:PEKK without Visio.link (Bredent, Senden, Germany)(U) and with Visio.link (P). Resins for temporary restoration (polymethylmethac-rylate; PMMA, polyethylmethacrylate; PEMA, bis-acryl composite resin) in the shape of a square with one side 3.2 mm were bonded to PEKK twenty respectively and classified into six groups (UM, UE, UC, PM, PE and PC). All specimens were stored in distilled water at 37°C for 24 hours. SBS of each group was measured at a crosshead speed of 2 mm/min in universal testing machine. SBS was compared using one-way ANOVA and a Tukey HSD test (P = 0.05). @*Results@#Group UM and group UE showed a significant difference in SBS with group UC (P < 0.05). Group PC showed a significant increase in SBS than group UC (P < 0.05). @*Conclusion@#It is recom-mended to apply Visio.link to PEKK for adhering bis-acrylic composite resin, but not for PMMA and PEMA in clinical practice.

Accuracy of dies fabricated by various three dimensional printing systems: a comparative study

Purpose@#The aim of this study was to compare the accuracy of dies fabricated using 3D printing system to conventional method and to evaluate overall volumetric changes by arranging the superimposed surfaces. @*Materials and Methods@#A mandibular right first molar from a dental model was prepared, scanned and fabricated with composites of polyetherketoneketone (PEKK). Master dies were classified into 4 groups. For the conventional method, the impression was taken with polyvinylsiloxane and the impression was poured with Type IV dental stone. For the 3D printing, the standard die was scanned and converted into models using three different 3D printers. Each of four methods was used to make 10 specimens. Scanned files were superimposed with the standard die by using 3D surface matching software. For statistical analysis, Kruskal-Wallis test and Mann-Whitney U test were done (P < 0.05). @*Results@#Compared to the standard model, the volumetric changes of dies fabricated by each method were significantly different except the models fabricated by conventional method and 3D printer of Stereolithography (P < 0.05). The conventional dies showed the lowest volumetric change than 3D printed dies (P < 0.05). 3D printed dies fabricated by Stereolithography showed the lowest volumetric change among the different 3D printers (P < 0.05). @*Conclusion@#The conventional dies were more accurate than 3D printed dies, though 3D printed dies were within clinically acceptable range. Thus, 3D printed dies can be used for fabricating restorations.

Comparative study of surface modification on bond strength of polyetherketoneketone adhesively bonded to resins for temporary restoration

Purpose@#The purpose was to compare shear bond strength (SBS) of three types of resin for temporary restoration to polyetherketoneketone (PEKK) depending on surface modification. @*Materials and Methods@#Sixty disks made from PEKK were air-abraded with 110 μm alumina particles (Cobra, Renfert GmbH, Hilzinge, Germany) and thirty specimens were divided into two groups each:PEKK without Visio.link (Bredent, Senden, Germany)(U) and with Visio.link (P). Resins for temporary restoration (polymethylmethac-rylate; PMMA, polyethylmethacrylate; PEMA, bis-acryl composite resin) in the shape of a square with one side 3.2 mm were bonded to PEKK twenty respectively and classified into six groups (UM, UE, UC, PM, PE and PC). All specimens were stored in distilled water at 37°C for 24 hours. SBS of each group was measured at a crosshead speed of 2 mm/min in universal testing machine. SBS was compared using one-way ANOVA and a Tukey HSD test (P = 0.05). @*Results@#Group UM and group UE showed a significant difference in SBS with group UC (P < 0.05). Group PC showed a significant increase in SBS than group UC (P < 0.05). @*Conclusion@#It is recom-mended to apply Visio.link to PEKK for adhering bis-acrylic composite resin, but not for PMMA and PEMA in clinical practice.

Accuracy of dies fabricated by various three dimensional printing systems: a comparative study

Purpose@#The aim of this study was to compare the accuracy of dies fabricated using 3D printing system to conventional method and to evaluate overall volumetric changes by arranging the superimposed surfaces. @*Materials and Methods@#A mandibular right first molar from a dental model was prepared, scanned and fabricated with composites of polyetherketoneketone (PEKK). Master dies were classified into 4 groups. For the conventional method, the impression was taken with polyvinylsiloxane and the impression was poured with Type IV dental stone. For the 3D printing, the standard die was scanned and converted into models using three different 3D printers. Each of four methods was used to make 10 specimens. Scanned files were superimposed with the standard die by using 3D surface matching software. For statistical analysis, Kruskal-Wallis test and Mann-Whitney U test were done (P < 0.05). @*Results@#Compared to the standard model, the volumetric changes of dies fabricated by each method were significantly different except the models fabricated by conventional method and 3D printer of Stereolithography (P < 0.05). The conventional dies showed the lowest volumetric change than 3D printed dies (P < 0.05). 3D printed dies fabricated by Stereolithography showed the lowest volumetric change among the different 3D printers (P < 0.05). @*Conclusion@#The conventional dies were more accurate than 3D printed dies, though 3D printed dies were within clinically acceptable range. Thus, 3D printed dies can be used for fabricating restorations.

Esthetic anterior restoration using 3M Lava™ Esthetic monolithic zirconia

Monolithic zirconia has been widely used in fixed partial dentures due to high strength and fracture toughness. Nevertheless, the usage of monolithic zirconia in anterior restoration was limited because of opacity. Recently, esthetic monolithic zirconia blocks are developed by improving translucency and using various shading systems. Manufacturer introduces 3M Lava™ Esthetic with increased cubic phase and fluorescent ingredients is more esthetic than previous monolithic zirconia. This case report describes favorable anterior restorations using translucent monolithic zirconia.

Comparative study of new bone formation capability of zirconia bone graft material in rabbit calvarial

PURPOSE: The purpose of this study was to compare the new bone formation capability of zirconia with those of other synthetic bone grafts. MATERIALS AND METHODS: Twelve rabbits were used and four 6-mm diameter transcortical defects were formed on each calvaria. Each defect was filled with Osteon II (Os), Tigran PTG (Ti), and zirconia (Zi) bone grafts. For the control group, the defects were left unfilled. The rabbits were sacrificed at 2, 4, and 8 weeks. Specimens were analyzed through micro computed tomography (CT) and histomorphometric analysis. RESULTS: The Ti and Zi groups showed significant differences in the amount of newly formed bone between 2 and 4 weeks and between 2 and 8 weeks (P < .05). The measurements of total bone using micro CT showed significant differences between the Os and Ti groups and between the Os and Zi groups at 2 and 8 weeks (P < .05). Comparing by week in each group, the Ti group showed a significant difference between 4 and 8 weeks. Histomorphometric analysis also showed significant differences in new bone formation between the control group and the experimental groups at 2, 4, and 8 weeks (P < .05). In the comparison of newly formed bone, significant differences were observed between 2 and 4 weeks and between 2 and 8 weeks (P < .05) in all groups. CONCLUSION: Zirconia bone graft material showed satisfactory results in new bone formation and zirconia could be used as a new synthetic bone graft material.

The influence of the number and the type of magnetic attachment on the retention of mandibular mini implant overdenture

PURPOSE: The aim of this study was to compare the retention of mini implant overdenture by the number, the type of magnetic attachment, and the directions of applied dislodging force. MATERIALS AND METHODS: The experimental groups were designed by the number and type of magnetic attachment. Twenty samples were tested with Magden implants. Each attachment was composed of the magnet assembly in overdenture sample and the abutment keeper in a mandibular model. Dislodging forces were applied to the overdenture samples (50.0 mm/min) in 3 directions. The loading was repeated 10 times in each direction. The values of dislodging force were analyzed statistically using SPSS at 95% level of confidence. RESULTS: The retentive force of group 2 was greater than that of group 1 in both types of attachment in every direction (P < .05). Oblique retentive force of flat type magnetic attachment was higher than that of cushion type attachment in both groups (P < .05). In group 1, oblique retentive force showed the highest and anterior-posterior retentive force showed the lowest value in both attachment types (P < .05). In group 2, both types of attachment showed the lowest retentive force with anteriorposterior direction of dislodging force (P <.05). CONCLUSION: Proper retentive properties for implant overdenture were obtained, regardless of the number and type of magnetic attachment. In both types of magnetic attachment, the greater retentive force was attained with more implants. Oblique retentive force of flat type magnetic attachment was greater than that of cushion type. Among all subgroups, anterior-posterior retentive force was the lowest among three different directions of dislodging force.

Implant-retained overdenture with CM LOC ® Pekkton® in maxillary edentulous patient

Treatment options for edentulous patients are complete denture and implant prosthesis. A two implant-retained overdenture can be considered the first treatment in the edentulous mandible, but there is no clear consensus of treatment for edentulous maxilla. Implant-retention/support overdenture shows better retention and stability than complete denture and is less expensive and more esthetic than implant-supported fixed prosthesis. CM LOC® Pekkton® attachment is a solitary type attachment and evaluated to have excellent abrasion resistance and retention with a female part made of poly-ether-ketone-ketone. Meanwhile, SR Ivocap system is injection molding method and discussed to show few changes in the vertical dimension of denture and have excellent fracture resistance. In this case, we restored maxillary arch with a four implant-retained overdenture using CM LOC® Pekkton® and SR Ivocap system, and mandibular arch with a removable partial denture. Through this procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

Analysis of maxillofacial prosthetics at university dental hospitals in the capital region of Korea

PURPOSE: The purpose of this study was to investigate the demographic patterns of maxillofacial prosthetic treatment to identify the characteristics and geographic distribution of patients with maxillofacial prosthetics in the capital region of Korea. MATERIALS AND METHODS: This retrospective analytical multicenter study was performed by chart reviews. This study included patients who visited the department of prosthodontics at four university dental hospitals for maxillofacial prosthetic rehabilitation. Patients with facial and congenital defects or with insufficient medical data were excluded. The patients were classified into three categories based on the location of the defect. Patients' sex, age, and residential area were analyzed. Pearson's chi-square test with a significance level of 0.05 was used to analyze the variables. RESULTS: Among 540 patients with maxillofacial prosthetics, there were 284 (52.59%) male patients and 256 (47.41%) female patients. The number of the patients varied greatly by hospital. Most patients were older than 70, and the most common defect was a hard palate defect. Chi-square analysis did not identify any significant differences in sex, age, and distance to hospital for any defect group (P>.05). CONCLUSION: The results of this study indicated that there was imbalance in the distribution of patients with maxillofacial prosthetic among the hospitals in the capital region of Korea. Considerations on specialists and insurance policies for the improvement of maxillofacial prosthetics in Korea are required.

Fixed prostheses fabricated by direct metal laser sintering system: case report

Nowadays, 3 dimentional (3D) printing, especially Direct Metal Laser Sintering (DMLS) system is used in dentistry. DMLS system has recently been introduced for fabrication metal framework for metal ceramic crowns to overcome the disadvantages of the casting method and computer aided design/computer aided manufacturing (CAD/CAM) milling system. DMLS system uses a high-temperature laser beam to selectively heat a substructure metal powder based on the CAD data with the framework design. A thin layer of the beamed area becomes fused, and the metal framework is completed by laminating these thin layers. Utilizing DMLS system to fabricate fixed prostheses is expected to achieve free-from shaping without mold and limitations from cutting tools, fabricate prostheses with complex geometry, prevent distortion and fabrication defects that inherent to conventional fabrication methods. The purpose of this case report is to demonstrate various fixed prostheses such as long span fixed prostheses, post to achieve satisfactory results in functional and esthetic aspects.

Prosthodontic problems and complications associated with osseointegration

Edentulous patients with a severely resorbed mandible or maxilla often experience problems with conventional dentures, such as insufficient stability and retention, together with a decrease in chewing ability. Because of the good prognosis of dental implants, these patients can be successfully treated with implant-retained or implant-supported prosthesis. Ideally, a maximum number of implants of maximum length are placed in appropriate surgically prepared sites that are surrounded by a maximum amount of bone of favorable quality. The implants are favorably aligned faciolingually and mesiodistally to enhance optimal prosthodontic design. This article describes the clinical problems and complications encountered when treating a consecutive number of edentulous patients with osseointegrated implant-supported prostheses.