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    Influence of digital implant analog design on the positional trueness of an analog in additively manufactured models: an in-vitro study
    (John Wiley and Sons Inc, 2022) Mata-Mata, Severino J.; Dönmez, Mustafa Borga; Meirelles, Luiz; Johnston, William Michael; Yılmaz, Burak
    Background: Limited evidence exists regarding the accuracy of implant analog position in printed models, particularly when implant analogs with varying designs are used. Purpose: To evaluate the effect of digital implant analog (DIA) design on the trueness of their position in additively manufactured digital implant models (DIMs) and to compare with that of a conventional implant analog in a stone cast. Materials and Methods: A dentate maxillary model with a conventional implant analog (Nobel Biocare Implant Replica 4.3 mm CC RP) at left second premolar site was digitized by using a laboratory scanner (3Shape D2000) and a (SB) scan body to generate the master standard tessellation language (STL) file (M0). 12 custom trays were fabricated on M0 file and conventional polyvinylsiloxane impressions of the model were made. All impressions were poured after inserting conventional implant analogs (Nobel RP Implant Replica) (Group A). Model was then digitized with an intraoral scanner (TRIOS 3) and the same SB, and DIMs with three different DIA designs (Nobel Biocare [Group B], Elos [Group C], and NT-trading [Group D]) were generated (Dental System-Model Builder). 12 DIMs of each design were additively manufactured and corresponding DIAs were inserted. All models were digitized by using the same laboratory scanner and SB, and these STLs were transferred to a 3D analysis software (Geomagic Control X), where the STL files of the models were superimposed over M0. Linear and 3D deviations at three selected points on SB (implant-abutment connection, most cervical point on SB, and most coronal point on SB) as well as angular deviations on two planes (buccolingual and mesiodistal) were calculated. Analysis of variance (ANOVA) and Bonferroni corrected t-tests were used to analyze the trueness of implant analog positions (? = 0.05). Results: The interaction of main effects significantly affected linear (p < 0.001) and angular deviations (p = 0.020). At point 1, group D had higher deviations than groups A and B (p ? 0.015). In addition, groups A and D had higher deviations than group B at point 4 (p < 0.001). While group C had similar linear deviations to those of other groups at point 1 and point 4 (p ? 0.192), the differences among test groups at point 2 were nonsignificant (p ? 0.276). Group B had lower angular deviations than groups C (p = 0.039) and D (p = 0.006) on buccolingual plane. Conclusions: Analog design affected the trueness of analog position as proprietary, pressure/friction fit DIA (group B) had higher linear trueness than screw-retained DIA (Group D) and conventional implant analog (group A). In addition, pressure/friction fit DIA had the highest angular trueness among tested DIAs.
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    Prosthetic complications with monolithic or micro-veneered implant-supported zirconia single-unit, multiple-unit, and complete-arch prostheses on titanium base abutments: a single center retrospective study with mean follow-up period of 72.35 months
    (WILEY, 2022) Saponaro, Paola C.; Karasan, Duygu; Dönmez, Mustafa Borga; Johnston, William Michael; Yılmaz, Burak
    Background The influence of prosthetic design on prosthetic complications when monolithic or micro-veneered zirconia prostheses are supported with titanium base (ti-base) abutments is not well-known. Purpose The purpose of this single center, retrospective study was to assess the prevalence of prosthetic complications with monolithic or micro-veneered single-unit, multi-unit, and complete-arch zirconia prostheses supported with ti-base abutments (implant level or multi-unit abutment level). Material and Methods This study retrospectively evaluated the electronic health record (EHR) of participants who received either monolithic or micro-veneered implant-supported single-unit, multi-unit, and/or complete-arch prostheses supported by ti-base or zirconia-ti-base hybrid abutments delivered between the years 2010 and 2021. Data were analyzed by using logistic regression and Exact Mantel-Haenszel chi-square test (alpha = 0.05) to assess the clinical performance of prostheses and complications including crown decementation, feldspathic porcelain chipping, prosthesis fracture, zirconia-ti-base hybrid abutment decementation, abutment screw loosening, screw fracture, abutment fracture, implant loss, and prosthesis remake. Results The study included 94 participants (50 female, 44 male) with a mean age of 59.5 years (range: 24-101 years of age). The retrospective EHR evaluation yielded 82 single-unit, 51 multi-unit, and 20 complete-arch prostheses on 325 implants. Among 153 prostheses delivered, 108 were micro-veneered (47 single-unit, 41 multi-unit, and 20 complete-arch prostheses) and 45 were monolithic. The average duration was 72.35 months (6.02 years) with a follow-up period of 5-132 months. From the time of insertion to the time of EHR review, of 153 prostheses, 78.43% did not exhibit any prosthetic complication. However, 33 prostheses (21.57%) from 29 participants (30.85%) had at least one prosthetic complication. Only four patients (4.25%) experienced two or more prosthetic complications. Prosthetic design affected the probability of having a complication (p = 0.005); complete-arch prostheses had higher probability (p <= 0.028). Single-unit prostheses had lower probability of complication than multi-unit prostheses (p = 0.005). The most commonly observed complication was fracture of veneering material (5.88%) followed by prosthetic screw loosening (4.57%) and decementation between the zirconia and the ti-base abutment (2.61%). Micro-veneered complete-arch prostheses had higher probability of having chipping than that of not having (p < 0.001), and other micro-veneered prosthetic designs had similar probability of chipping with that of complete-arch prostheses (p >= 0.082). Frequency of chipping was affected by veneering (p < 0.001). Monolithic prostheses had lower probability of chipping than micro-veneered prostheses, regardless of the prosthetic design (p < 0.001). Conclusions The frequency of prosthetic complications varied depending on prosthetic design. Complete-arch prostheses had the highest probability of complications while the single-unit prostheses had the lowest. Micro-veneered prostheses had higher probability for chipping than monolithic prostheses. Probability of chipping was similar for micro-veneered single-unit, multi-unit, and complete-arch zirconia prostheses.