The International Journal of Prosthodontics, 05/2020

Purpose: The aim of the present study was to assess the perceptibility and acceptability threshold values for color differentiation at the restoration and mucosa levels. Materials and Methods: One restored single-tooth implant and the contralateral reference tooth were spectrophotometrically assessed in 20 patients. Perceptibility and acceptability were evaluated by dentists, dental technicians, and laypeople. Results: Dental technicians had the highest sensitivity in the perception of tooth color differences (ΔE = 2.7), followed by dentists (ΔE = 3.3) and laypeople (ΔE = 4.4). Acceptability threshold values were generally higher than perceptibility threshold in all groups. Dental technicians exhibited the highest sensitivity in the perception of mucosa color differences (50% perceptibility at ΔE = 2.65), followed by dentists (ΔE > 3.7) and laypeople (ΔE > 6). Conclusion: Color differences were tolerated with varying degrees among the three groups. Laypeople accepted higher color differences at the mucosa level.

Purpose: To describe and analyze the restorative complications of long-span (> three units) implantsupported dental prostheses (LIDPs) in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. Materials and Methods: Private dental practitioners providing implant treatment were invited to enroll in this study, which was conducted through a dental practice-based research network. Clinical records of the implant treatments, which were provided during the specified period, were accessed for data collection. LIDPs included implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs). Descriptive statistics and generalized linear mixed modeling were used for data analysis. Results: The range of observation time for 627 LIDPs was 3 to 72 months (mean ± SD: 3.22 ± 1.49 years). For fixed prostheses, the complication with the highest annual rate was veneer fracture (acrylic: 21%; ceramic: 2.9%), followed by loss of retention for cement-retained IFPDs (14.7%). For mandibular IODs, the highest annual complication rate was for retention complications, whereas for maxillary IODs, it was for acrylic veneer fracture (11.5% and 6.4%, respectively). The peak incidence of complications was during the first year of function in fixed protheses and in IODs. Acrylic veneer fracture in IFCDs and IOD base fracture were more common in patients with preoperative clinician-reported attrition (estimated odds ratios [ORs] = 4.5 and 11.3, respectively; P < .05). Ceramic veneer fracture in fixed protheses and acrylic veneer fracture in IODs were reported more commonly for maxillary compared to mandibular prostheses (ORs = 5 and 22, respectively; P < .05). Mandibular IODs had more frequent retention complications when supported by two compared to four implants (OR = 5.9, P < .05). Conclusion: Restorative complications were observed in all categories of LIDPs at various annual rates. Clusters of these complications occurred during the first year of prosthesis function. Patient- and prosthesis-related variables influenced the incidence rate of some of these complications.

Purpose: To assess the clinical outcomes of single-retainer resin-bonded fixed dental prostheses (RBFDPs) and the profilometric changes of pontic sites after a mean of 10 years in function. Materials and Methods: Ten patients (mean age 32.4 years) who had received an RBFDP replacing a single anterior tooth were recalled after 10 years. Five patients had received a subepithelial connective tissue graft (SCTG) at the pontic site. The clinical assessment comprised the following parameters: probing depth, bleeding on probing, modified plaque control record, gingival recession, measurement of the width of keratinized mucosa, and intraoral photographs and radiographs. The modified criteria of the United States Public Health Services evaluation system were applied. Additionally, patient satisfaction was recorded. Data were analyzed descriptively, and the 10-year RBFDP survival rates were calculated using Kaplan-Meier analysis. Results: The RBFDP survival rate after a mean follow-up of 10.0 years (range 7.4 to 13.3 years) was 100%. Neither technical failures nor biologic complications were observed. All abutment teeth remained vital, and no secondary caries were detected. Between baseline and follow-up examinations, the profilometric changes at the pontic sites were minimal, exhibiting a loss of –0.03 ± 0.10 mm (no SCTG) and 0.00 ± 0.37 mm (SCTG). Conclusion: The present study exhibited high survival rates and low complication rates of the restorations, as well as excellent profilometric stability of the pontic sites over 10 years. The use of an RBFDP is a viable long-term treatment option for replacing a single anterior tooth.

Purpose: To compare clinical and esthetic outcomes between immediately loaded single implants placed with and without a fully guided surgical procedure. Materials and Methods: Patients with a missing maxillary tooth (second premolar to second premolar) were considered for inclusion in this 1-year prospective nonrandomized study. Exclusion criteria were general health contraindications for oral surgery besides the need for bone grafting or ridge augmentation. One group received digital implant planning, fully guided surgery, and immediate loading (DIL). The other group received freehand surgery and immediate loading (IL). Outcome measures were implant survival, marginal bone loss, soft tissue changes, papilla index, pink and white esthetic scores (PES and WES, respectively), and patient-reported outcome measures (PROMs). Results: Two of 21 implants failed in the DIL group soon after placement, resulting in a 1-year implant survival rate of 90.5%, while no implants failed in the IL group. Significantly higher papilla index scores and lower soft tissue changes were found for the DIL group compared to the IL group. No differences were found after 1 year regarding marginal bone loss, PES, WES, or PROMs. Conclusion: Within the limitations of this study, immediate loading in combination with fully guided surgery might negatively affect implant survival. Immediate loading, fully guided surgery, and a digital workflow appear to have a positive effect on early soft tissue adaptation.

Purpose: To investigate the three-point flexural strength of a novel CAD/CAM fiber-reinforced composite (FRC) material following different aging conditions. Materials and Methods: The specimens were randomly assigned to one of five groups based on aging condition: (1) control (no treatment); (2) short-term water storage; (3) thermal degradation with autoclaving; (4) chemical degradation with hydrochloric acid; and (5) chemical degradation with citric acid (n = 10 per group). The specimens in the control group received no treatment. Following each treatment protocol, the three-point bending test was used to calculate the flexural strength. Data were statistically analyzed (α = .05), and scanning electron microscopy (SEM) analysis of the specimens was conducted. Results: No significant differences in flexural strength were observed among the groups (P = .199). In addition, no distinct morphologic differences were detected in the SEM images of the specimens. Conclusion: The flexural strength of this novel CAD/CAM FRC material was unaffected by different aging methods.

Purpose: To establish the most effective cementation protocol for bonding zirconia crowns to Ti-Base CAD/CAM abutments in terms of abutment height, cement type, and surface pretreatment. Materials and Methods: Zirconia crowns were designed to fit abutments of 2.5-mm (short) and 4.0-mm (tall) height. The retention of conventional resin cement with a universal adhesive (RelyX Ultimate, 3M ESPE) was compared to self-adhesive resin cement (RelyX U200, 3M ESPE) following different surface pretreatments (n = 10/ group): (1) no treatment (NT); (2) Ti-Base abutment surface blasting with alumina particles (SB); (3) zirconia crown tribochemical surface blasting with silica-coated alumina particles (TBS); and (4) a combination of SB + TBS. Pull-out testing was performed in a universal testing machine. Data were statistically evaluated using a linear mixed model following least significant difference post hoc test. Results: Pull-out data as a function of Ti-Base height demonstrated higher retention for tall compared to short abutments (P < .001). Ultimate outperformed U200 cement (data collapsed over height and pretreatment) (P < .001). Analysis of pretreatment depicted higher retention for SB + TBS, followed by SB, TBS, and NT (P < .04). The interaction between Ti-Base height and cement type highlighted the superior adhesive strength of Ultimate compared to U200 for both heights (P < .001). Irrespective of type of pretreatment, surface pretreatment improved the retention for U200 cement and short Ti-Base (P < .03 compared to NT). In contrast, higher retention was demonstrated for SB + TBS, followed by SB, TBS, and NT, for Ultimate cement combined with tall Ti-Base (P < .02) (data collapsed over height and cement, respectively). Conclusion: There was a direct relationship among Ti-Base height, micromechanical and/or chemical pretreatment, and conventional adhesive bonding in improving the retention of zirconia crowns.

Purpose: To evaluate the shear bond strength (SBS) and color stability (ΔE) of four ceramic veneers (VITA VM 9; VITA VM 13; VITA VMK 95; and IPS e.max Ceram) following repair with three different self-adhesive composite resins (Fusio Liquid Dentin; Constic; and Vertise Flow) and BISCO Intraoral Repair Kit + Filtek Supreme (BC + FS). Materials and Methods: A total of 96 specimens were prepared per ceramic material, and each ceramic group was divided into subgroups according to testing method (32 specimens for color stability analysis and 64 specimens for SBS testing). ΔE and SBS (SBS1 = non-aged, SBS2 = thermally aged) values of the repaired specimens were calculated. One specimen from each of the thermally aged groups was investigated under scanning electron microscopy (SEM). Two-way ANOVA was used to analyze the mean ΔE, SBS1, and SBS2 values. The differences between SBS1 and SBS2 values were analyzed using independentsamples t test. Results: The lowest ΔE values were calculated for Constic (P ≤ .05). The SBS2 values among all groups were lower than the SBS1 values (P ≤ .05). The lowest SBS2 values were observed for Vertise Flow (2.3 ± 1.47 MPa) (P ≤ .05) and were below the acceptable limit of 5 MPa. Conclusion: All of the investigated repair materials in combination with the ceramic veneers exhibited ΔE values that were higher than the clinically acceptable limits. Thermal aging negatively affected the SBS values in all groups (P ≤ .05). All tested self-adhesive composite resins, with the exception of Vertise Flow, could be used instead of a repair kit with flowable composite resin, especially in noncooperative patients, for the purpose of repairing chipping fractures for VITA VM 9, VITA VM 13, and VITA VMK 95 (P > .05).

Purpose: To evaluate the effect of cementation protocols on the bonding interface stability and pull-out forces of temporary implant-supported crowns bonded on a titanium base abutment (TiB) or on a temporary titanium abutment (TiA). Materials and Methods: A total of 60 implants were restored with PMMA-based CAD/CAM crowns. Five groups (n = 12) were created: Group 1 = TiB/SRc: crown conditioned with MMA-based liquid (SR Connect, Ivoclar Vivadent); Group 2 = TiB/50Al-MB: crown airborne particle–abraded with 50-μm Al2O3 and silanized (Monobond Plus, Ivoclar Vivadent); Group 3 = TiB/30SiOAl-SRc: crown airborne particle–abraded with 30-μm silica-coated Al2O3 (CoJet, 3M ESPE) and conditioned with MMA-based liquid (SR Connect); Group 4 = TiB/30SiOAl-MB: crown airborne particle–abraded with 30- μm silica-coated Al2O3 (CoJet) and silanized (Monobond Plus); and Group 5 = TiA/TA-PMMA: crown manually enlarged, activated, and rebased with PMMA resin (Telio Lab, Ivoclar Vivadent). Specimens in the TiB groups were cemented using a resin cement (Multilink Hybrid Abutment, Ivoclar Vivadent). After aging (120,000 cycles, 49 N, 1.67 Hz, 5°C to 55°C, 120 seconds), bonding interface failure was analyzed (50x). Pull-out forces (N) (0.5 mm/minute) and modes of failure were registered. Chi-square and Kruskal-Wallis tests were used to analyze the data (α = .05). Results: Bonding failure after aging varied from 0% (Group 5) to 100% (Groups 1, 2, and 4) (P < .001). Mean pull-out force ranged between 53.1 N (Group 1) and 1,146.5 N (Group 5). The pull-off forces were significantly greater for Group 5 (P < .05), followed by Group 3 (P < .05), whereas the differences among the remaining groups were not significant (P > .05). Conclusion: The cementation protocol had an effect on the bonding interface stability and pull-out forces of PMMA-based crowns bonded on a titanium base. Airborne particle abrasion of the crown internal surface and conditioning it with an MMA-based liquid may be recommended to improve retention of titanium base temporary restorations. Yet, for optimal outcomes, conventional temporary abutments might be preferred.

Purpose: To systematically review the literature comparing marginal bone loss (MBL) and pink esthetic scores of implants with convergent or concave transmucosal profiles vs divergent or parallel profiles. Materials and Methods: A PICO question was defined, and an electronic search was carried out in the MEDLINE/PubMed and Cochrane Oral Health Group databases. Studies documenting type of transmucosal profile (either tissuelevel profiles or abutments) and soft and/or hard tissue outcomes of implants were considered eligible. Studies were selected on the basis of the inclusion criteria and quality assessments. A meta-analysis with subgroup analyses was performed. Results: Five papers fulfilled the inclusion criteria, and four were eligible for metaanalysis. Significantly less MBL was found in concave/convergent groups, with a mean difference of 0.772 (95% confidence interval [CI]: 0.450 to 1.095; P < .001). In the subgroup analyses for platform-switching and platform-matching connections, a significant effect in favor of concave/convergent was detected, with a standardized difference in means of 1.135 (95% CI: 0.688 to 1.583, P < .001) when platform switching was considered. No significant effects were found for platform-matching connections. Conclusion: Within the limitations of this review, it is suggested that concave/convergent implant transmucosal profiles result in less MBL. No statistically significant results were obtained for soft tissue–related outcomes or for the platformmatching connection subgroup.

This case history report describes a comprehensive digital workflow for implant treatment and occlusal reconstruction to provide a systematic protocol for implant-supported restorations in edentulous patients. In this case, a restoration-oriented surgical protocol was created using an oral implant planning and design software. The implant surgery was completed under the guidance of a fully guided surgical template. This is the first report of the combined application of computer-aided diagnosis axiograph and neuromuscular evaluation systems in implant-supported occlusal reconstruction. Digital technologies can increase the accuracy, efficiency, and comfort of implant treatment and achieve satisfactory occlusal reconstruction outcomes in edentulous patients.

A 54-year-old woman presented with severe maxillary resorption, which resulted in an unstable maxillary removable denture. Due to poor anatomical conditions, the prosthodontic solution posed for the patient was an implant-supported maxillary overdenture based on four implants. This report presents the detailed workflow for CAD/CAM–fabricated, individually milled zirconia bars and an electroplated superstructure framework for an implant-supported removable overdenture, which enabled good retention and an optimal esthetic result. A critical element in the present case was the production of electroplated secondary elements, which are highly precise, with a homogenous layer of gold. No retention loss was observed after 12 months in use.

A new-generation mini-implant system offers a polyether ether ketone matrix and a new-generation surface technology on its patrix. This clinical report describes the treatment of a patient with a new-generation miniimplant– retained maxillary overdenture.