Survival and complication rates of tooth- and implant-supported restorations after an observation period up to 36 years.

BACKGROUND: Tooth- and implant-supported fixed dental prostheses are well-documented and aesthetic treatment alternatives, and after a comprehensive periodontal treatment, a protocol with a good long-term prognosis if the maintenance program is strictly followed. AIM: To reexamine a pre-existing patient cohort in order to obtain estimated long-term survival and complication outcomes of fixed dental prostheses. MATERIALS AND METHODS: For this study, patients treated with fixed dental prostheses between 1978 and 2002 were reexamined between 2019 and 2020. The restorations were divided in single crowns and fixed dental prostheses supported by teeth (TSC, FPTDP) and implants (ISC, FPIDP). Survival and complication rates were obtained. Kaplan-Meier functions were used to model complication probabilities, and average hazard ratios of different strata were compared using weighted Cox regression. RESULTS: The mean observation time of 40 patients and 223 reconstructions was 20.3 (±9.7, 1.2-36.2) years. The estimated survival rates were 84% (CI: 77%-92%) for TSC, 63% (CI: 51%-79%) for FPTDP, 87% (CI: 71%-100%) for ISC, and 64% (CI: 34%-100%) for FPIDP after 25 years. Biological complications included carious lesions (10.6%), periodontitis (7.9%), and peri-implantitis (6.8%). Technical complications included chipping (20.2%) and loss of retention (10.8%). CONCLUSION: Biological complications lead to abutment loss in more than two-thirds of cases, regardless of the type of abutment (tooth or implant). Technical complications are less associated with abutment loss than biological complications.

Scan accuracy and time efficiency of different implant-supported fixed partial denture situations depending on the intraoral scanner and scanned area: An in vitro study.

STATEMENT OF PROBLEM: The type of intraoral scanner (IOS), region of the implant, and extent of the scanned area have been reported to affect scan accuracy. However, knowledge of the accuracy of IOSs is scarce when digitizing different partially edentulous situations either with complete- or partial-arch scans. PURPOSE: The purpose of this in vitro study was to investigate the scan accuracy and time efficiency of complete- and partial-arch scans of different partially edentulous situations with 2 implants and 2 different IOSs. MATERIAL AND METHODS: Three maxillary models with implant spaces at the lateral incisor sites (anterior 4-unit), right first premolar and right first molar sites (posterior 3-unit), or right canine and right first molar sites (posterior 4-unit) were fabricated. After placing implants (Straumann S RN) and scan bodies (CARES Mono Scanbody), models were digitized by using an optical scanner (ATOS Capsule 200MV120) to generate reference standard tessellation language (STL) files. Complete- or partial-arch scans (test scans) of each model were then performed by using 2 IOSs (Primescan [PS] and TRIOS 3 [T3]) (n=14). The duration of the scans and the time needed to postprocess the STL file until the design could be started were also recorded. A metrology-grade analysis software program (GOM Inspect 2018) was used to superimpose test scan STLs over the reference STL to calculate 3D distance, interimplant distance, and angular (mesiodistal and buccopalatal) deviations. Nonparametric 2-way analysis of variance followed by Mann-Whitney tests with Holm correction were used for trueness, precision, and time efficiency analyses (α=.05). RESULTS: The interaction between IOSs and scanned area only affected the precision of the scans when angular deviation data were considered (P≤.002). Trueness of the scans was affected by IOSs when 3D distance, interimplant distance, and mesiodistal angular deviations were considered. The scanned area affected only 3D distance deviations (P≤.006). IOSs and scanned area significantly affected the precision of scans when 3D distance, interimplant distance, and mesiodistal angular deviations were considered, while only IOSs significantly affected buccopalatal angular deviations (P≤.040). Scans from PS had higher accuracy when 3D distance deviations were considered for the anterior 4-unit and posterior 3-unit models (P≤.030), when interimplant distance deviations were considered for complete-arch scans of the posterior 3-unit model (P≤.048), and when mesiodistal angular deviations were considered in the posterior 3-unit model (P≤.050). Partial-arch scans had higher accuracy when 3D distance deviations of the posterior 3-unit model were considered (P≤.002). PS had higher time efficiency regardless of the model and scanned area (P≤.010), while partial-arch scans had higher time efficiency when scanning the posterior 3-unit and posterior 4-unit models with PS and the posterior 3-unit model with T3 (P≤.050). CONCLUSIONS: Partial-arch scans with PS had similar or better accuracy and time efficiency than other tested scanned area-scanner pairs in tested partial edentulism situations.

Persistence of Porphyromonas gingivalis is a negative predictor in patients with moderate to severe periodontitis after nonsurgical periodontal therapy.

OBJECTIVES: The aim of this study was to evaluate the quality of prediction for stable results after nonsurgical periodontal therapy by several microbiological variables of the subgingival biofilm and biomarkers of gingival crevicular fluid or oral lavage. MATERIAL AND METHODS: Forty-six individuals with moderate or severe chronic periodontitis receiving nonsurgical periodontal therapy were monitored for clinical variables, selected microorganisms, and biomarkers at baseline and 3 and 6 months thereafter. Logistic regression analysis and general linear model (GLM) were applied for analysis of variance and covariance. RESULTS: At 6 months, 20 patients showed a high response (HR) to treatment (at least 60 % of reduction of numbers of sites with PD >4 mm), whereas 26 did not (low response, LR). All clinical variables were significantly improved at 3 and 6 months within each group (p < 0.001, each compared with baseline). Modeling the impact of Porphyromonas gingivalis, Treponema denticola, and median of MMP-8 on to the response to treatment as continuous variables by GLM showed a significant influence of these variables (p = 0.045) with the strongest influence of P. gingivalis (p = 0.012) followed by T. denticola (p = 0.045) and no association with MMP-8 (p = 0.982). Samples tested positively for P. gingivalis decreased only in HR (3 months: p = 0.003; 6 months: p = 0.002). Calprotectin levels in GCF were lower in the HR group compared with the LR group at 3 months (p = 0.008) and at 6 months (p = 0.018). CONCLUSION: Persistence of P. gingivalis combined with a high GCF level of calprotectin may have a negative predictive value on response to periodontal therapy. CLINICAL RELEVANCE: Microbiological diagnostics for P. gingivalis before and 3 months after SRP may have a predictive value on response to periodontal therapy. The combination with MMP-8 in oral lavage or preferably calprotectin in GCF might give additional information.

Soft Loading Protocol of Short Strategic Implants in Posterior Mandibles Supporting Removable Bilateral Free-End Prostheses: 1-year Results of a Prospective Cohort Study.

PURPOSE: To evaluate 1-year survival and success rates of 6-mm short implants placed in mandibular molar sites with two different abutments (dome/ball) retaining existing removable partial dentures (RPDs). MATERIALS AND METHODS: In 19 patients, 38 implants of 6-mm length were placed bilaterally. After 4 months, each participant received the dome abutment, which 2 months later was exchanged with the ball abutment. Clinical data were recorded at abutment connection (4 months postsurgery) and at 6 and 12 months postsurgery, including probing depth, bleeding on probing, presence of plaque, and standardized radiographs. Implant success was assessed using the following criteria: presence of pain, mobility, radiographic bone loss, probing depth, and the presence of exudate. For descriptive analyses, mean and SD values were calculated. Paired sample t tests and linear regressions with a significance level of α < .05 were applied to analyze the evolution of peri-implant parameters and the influence of implant placement depth. RESULTS: The overall mean marginal bone level alteration (DMBL) was 1.05 ± 0.69 mm. A statistically significant marginal bone loss over time was observed at the mesial and distal aspects of all implants (P < .05). The implant survival rate was 100%. No implants showed pain, exudate, mobility, or probing depth > 7 mm. Three implants were classified as having satisfactory survival due to a DMBL > 2 mm (resulting success rate: 92.1%). No influence of implant placement depth was found. CONCLUSION: These short-term results suggest that short implants can be used in mandibular molar sites for additional posterior support of free-end RPDs. However, in individual cases, DMBL > 2 mm may occur.

Effect of intraoral scanner and fixed partial denture situation on the scan accuracy of multiple implants: An in vitro study.

BACKGROUND: Accuracy of intraoral implant scans may be affected by the region of the implant and the type of the intraoral scanner (IOSs). However, there is limited knowledge on the scan accuracy of multiple implants placed for an implant-supported fixed partial denture (FPD) in different partially edentulous situations when digitized by using different IOSs. PURPOSE: To investigate the effect of IOS and FPD situation on the scan accuracy of two implants when partial-arch scans were performed. MATERIALS AND METHODS: Tissue level implants were placed in 3 maxillary models with implant spaces either at right first premolar and right first molar sites (Model 1, 3-unit FPD), at right canine and right first molar sites (Model 2, 4-unit FPD), or at lateral incisor sites (Model 3, 4-unit FPD). Reference standard tessellation language (STL) files of the models were generated by using an optical scanner (ATOS Capsule 200MV120). Two IOSs (CEREC Primescan [CP] and TRIOS 3 [TR]) were used to perform partial-arch scans (test-scans) of each model (n = 14), which were exported in STL format. A metrology-grade analysis software (GOM Inspect 2018) was used to superimpose test-scan STLs over the reference STL to calculate 3D distance, inter-implant distance, and angular (mesiodistal and buccopalatal) deviations. Trueness and precision analyses were performed by using bootstrap analysis of variance followed by Welch tests with Holm correction (α = 0.05). RESULTS: Trueness of the scans was affected by IOS and FPD situation when 3D distance deviations were considered, while inter-implant distance, mesiodistal angular, and buccopalatal angular deviations were only affected by the FPD situation (p < 0.001). Scan precision was affected by the interaction between the IOSs and the FPD situation when 3D distance and buccopalatal angular deviations were concerned, while IOSs and FPD situation were effective when all deviations were concerned (p≤ 0.001). When 3D distance deviations were considered, CP scans had higher accuracy TR scans in Models 1 and 3 (p ≤ 0.002), and the Model 1 scans had the highest accuracy (p < 0.001). When inter-implant distance deviations were considered, Model 1 scans had the highest accuracy with CP and higher accuracy than Model 2 when TR was used (p ≤ 0.030). When mesiodistal angular deviations were considered, Model 1 scans had the highest accuracy (p ≤ 0.040). When buccopalatal angular deviations were considered, Model 1 scans had the highest accuracy among models when CP was used (p ≤ 0.020). CONCLUSIONS: Posterior 3-unit fixed partial denture implant scans, CP scans, and combination of these two factors had accuracy either similar to or better than their tested counterparts.

In vitro scan accuracy and time efficiency in various implant-supported fixed partial denture situations.

OBJECTIVES: To compare the accuracy and time efficiency of different digital workflows in 3 implant-supported fixed partial denture situations. METHODS: Three partially edentulous maxillary models with 2 implants (Model 1: implants at lateral incisor sites; Model 2: implants at right canine and first molar sites; Model 3: implants at right first premolar and first molar sites) were digitized (ATOS Capsule 200MV120, n=1) for reference scans. Test scans were performed for direct (Primescan (DDW-P) and Trios 3 (DDW-T)) and indirect (IDW) digital workflows (n=14). For IDW, stone casts (type IV) were obtained from vinylsiloxanether impressions and digitized (S600 Arti). The scan/impression and post processing times were recorded. Reference and test scans were superimposed (GOM Inspect) to calculate 3D point, inter-implant distance, and angular deviations. Kruskal-Wallis and Mann-Whitney tests were used for trueness and precision analyses (α=.05). RESULTS: Tested workflows affected trueness (P≤.030) and precision (P<.001) of scans (3D point, inter-implant distance, and angular deviations) within models. DDW-P had the highest accuracy (3D point deviations) for models 1 and 3 (P≤.046). IDW had the lowest accuracy for model 2 (P<.01). DDW-P had the highest accuracy (inter-implant distance deviations) for model 3 (P≤.048). Direct digital workflow mostly led to lower angular deviations (P≤.040), and higher precision for models 2 (mesiodistal direction) and 3 (P<.001). The time for direct digital workflow was shorter (P<.001), DDW-P being more efficient than DDW-T (P=.008). CONCLUSION: Direct digital workflow was more accurate and efficient than indirect digital workflow in tested partial edentulism situations with 2 implants. CLINICAL SIGNIFICANCE: Tested intraoral scanners can be recommended for accurate and efficient impressions of anterior and posterior 3- or 4-unit implant-supported fixed partial dentures.