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PURPOSE@#. This study aims to clinically compare the fitness and trueness of zirconia crowns fabricated by different combinations of open CAD-CAM systems. @*MATERIALS AND METHODS@#. Total of 40 patients were enrolled in this study, and 9 different zirconia crowns were prepared per patient. Each crown was made through the cross-application of 3 different design software (EZIS VR, 3Shape Dental System, Exocad) with 3 different processing devices (Aegis HM, Trione Z, Motion 2). The marginal gap, absolute marginal discrepancy, internal gap(axial, line angle, occlusal) by a silicone replica technique were measured to compare the fit of the crown. The scanned inner and outer surfaces of the crowns were compared to CAD data using 3D metrology software to evaluate trueness. @*RESULTS@#. There were significant differences in the marginal gap, absolute marginal discrepancy, axial and line angle internal gap among the groups (P .05). @*CONCLUSION@#. All 9 groups showed clinically acceptable level of marginal gaps ranging from 74.26 to 112.20 μm in terms of fit comparison. In the comparison of trueness, no significant difference within each group was spotted. Within the limitation of this study, open CAD-CAM systems used in this study can be assembled properly to fabricate zirconia crown. [J Adv Prosthodont 2023;15:155-70]
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PURPOSE@#This prospective clinical study was conducted to evaluate the clinical usefulness of the freely detachable zirconia ball- and spring-retained implant prosthesis (BSRP) through a comparative analysis of screw- and cement-retained implant prosthesis (SCRP). @*MATERIALS AND METHODS@#A multi-center, randomized, prospective clinical study evaluating the clinical usefulness of the detachable zirconia ball- and spring-retained implant prostheses was conducted. Sixty-four implant prostheses in 64 patients were examined. Periodic observational studies were conducted at 0, 3, 6, and 12 months after delivery of the implant prosthesis. Factors such as implant success rate, marginal bone resorption, periodontal pocket depth, plaque and bleeding index, and prosthetic complications were evaluated, respectively. @*RESULTS@#During the 1-year observation period, all implants survived without functional problems and clinical mobility, showing a 100% implant success rate. Marginal bone resorption was significantly higher in the SCRP group than in the BSRP group only at the time of implant prosthesis delivery (P = .043). In all observation periods, periodontal pocket depth was slightly higher in the BSRP group than in the SCRP group, but there was no significant difference (P > .05). The modified plaque index (mPI) scores of both groups were moderate. Higher ratio of a score 2 in modified sulcus bleeding index (mBI) was observed in the BSRP group in the 6- and 12-months observation. @*CONCLUSION@#Within the limitations of this study, the newly developed zirconia ball- and spring-retained implant prosthesis could be considered as an applicable and predictable treatment method along with the existing screw- and cement-retained prosthesis.
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Mini-implant has been reported as an alternative method to conventional diameter implants in the treatment of mandibular anterior region with narrow ridge. However, one-piece type mini-implant showed biological and technical complications, such as peri-implantitis by residual cement and prosthetic detachment. Recently, one-piece type mini-implant with additional retentive structure has been introduced to increase the retention and stability of the mini-implant. The mini-implant is based on spreading the upper retentive structure with a spreader and connected it with the inner surface of the zirconia prosthesis. In two cases, we tried to reduce these complications through the mini-implant on the narrow mandibular anterior region, and it was possible to reduce the overall treatment period through a digital system. In this case report, restoration using the digital mini-implant system showed improvement of patient satisfaction on the aspect of function and esthetic in the narrow mandibular anterior region.
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PURPOSE@#The purpose of this study was to investigate changes in retention and wear pattern of Locator® and ADD-TOC attachments on a digital milled bar by performing chewing simulation and repeated insertion/removal of prostheses in fully edentulous models. @*MATERIALS AND METHODS@#Locator (Locator®; Zest Anchors Inc., Escondido, CA, USA) was selected as the control group and ADD-TOC (ADDTOC; PNUAdd Co., Ltd., Busan, Republic of Korea) as the experimental group. A CAD-CAM milled bar was mounted on a master model and 3 threaded holes for connecting a bar attachment was formed using a tap. Locator and ADD-TOC attachments were then attached to the milled bar. Simulated mastication and repeated insertion/removal were performed over 400,000 cyclic loadings and 1,080insertions/removals, respectively. Wear patterns on deformed attachment were investigated by field emission scanning electron microscopy. @*RESULTS@#For the ADD-TOC attachments, chewing simulation and repeated insertion/removal resulted in a mean initial retentive force of 24.43 ± 4.89 N, which were significantly lower than that of the Locator attachment, 34.33 ± 8.25 N (P < .05). Amounts of retention loss relative to baseline for the Locator and ADD-TOC attachments were 21.74 ± 7.07 and 8.98 ± 5.76 N (P < .05). @*CONCLUSION@#CAD-CAM milled bar with the ADD-TOC attachment had a lower initial retentive force than the Locator attachment. However, the ADD-TOC attachment might be suitable for long-term use as it showed less deformation and had a higher retentive force after simulated mastication and insertion/removal repetitions.
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PURPOSE: This study was undertaken to compare fracture and flexural strength of provisional restorative resins fabricated by additive manufacturing, subtractive manufacturing, and conventional direct technique. MATERIALS AND METHODS: Five types of provisional restorative resin made with different methods were investigated: Stereolithography apparatus (SLA) 3D printer (S3Z), two digital light processing (DLP) 3D printer (D3Z, D3P), milling method (MIL), conventional method (CON). For fracture strength test, premolar shaped specimens were prepared by each method and stored in distilled water at 37℃ for 24 hours. Compressive load was measured using a universal testing machine (UTM). For flexural strength test, rectangular bar specimens (25 × 2 × 2 mm) were prepared by each method according to ISO 10477 and flexural strength was measured by UTM. RESULTS: Fracture strengths of the S3Z, D3Z, and D3P groups fabricated by additive manufacturing were not significantly different from those of MIL and CON groups (P>.05/10=.005). On the other hand, the flexural strengths of S3Z, D3P, and MIL groups were significantly higher than that of CON group (P<.05), but the flexural strength of D3Z group was significantly lower than that of CON group (P<.05). CONCLUSION: Within the limitation of our study, provisional restorative resins made from additive manufacturing showed clinically comparable fracture and flexural strength as those made by subtractive manufacturing and conventional method.
Assuntos
Dente Pré-Molar , Mãos , Métodos , Impressão Tridimensional , ÁguaRESUMO
The propose of this study was to quantify the changes of soft tissue profile following orthodontic treatment and to evaluate the relationship of those to the skeletal elements. Pre-and post-treatment lateral cephalometric head films of 40 cases(20 extraction cases, 20 non-extraction camas) were traced, and the changes following treatment were measured and quantified by digital subtraction method, and statisticall analyzed. The obtained results were as follows; 1. in extraction group, the change of upper lip area(UL) was 558.60+/-355.17 pixels, that of lower lip area(LL) was 941.15+/-364.07 pixels. But, in non-extraction group the change of uper lip area(UL) was 125.65+/-404.16 pixels, that of lower lip area(LL) was 104.05+/-440.93 pixels, which was significantly lesser than those in extraction group. 2. In extraction group, there was significant correlationship between upper lip area change(UL) and difference of upper incisor point(deltaUIP). Lower lip area change(LL) was significantly correlated with difference of upper incisor(deltaUIP), difference of Frankfort upper incisor angle(deltaFUIA) or difference of interincisal angle(deltaIIA). 3. In extraction group, the ratio of difference of upper incisor point(deltaUIP) to difference of labrale superius(deltaLS) was 1.68; difference of lower incisor point(deltaLIP) to difference of labrale inferius(deltaLI) was 1.19; difference of upper incisor point(deltaUlP) to increment in upper lip thickness(deltaTUL) was 1.95. 4. In non-extraction group, there was a significant cortelationship between upper lip area change(UL) and difference of upper incisor point(deltaUIP).