The fracture strength and the failure mode of lithium disilicate or resin nano ceramics as a crown, overlay, or endocrown restoration on endodontically treated teeth.

INTRODUCTION: Different materials and restorative concepts have been proposed over the years to restore endodontically treated teeth (ETT). Monolithic ceramic and composite restoration can be lute to the tooh, without the use of a post. However, little is known how the material stiffness and presence of a composite core will affect the survival and failure mode. The objective of this in-vitro study was to evaluate the fracture strength and failure mode of endodontically treated molars, restored with ceramic or hybrid composite monolithic restoration, in the presence of absence of a composite core. MATERIALS AND METHODS: Sixty depulped molars were restored with a lithium-disilicate (e.max CAD) or hybrid composite (Cerasmart) restoration. Both materials were used in a monolithic approach, but with 3 different designs: (a) monolithic endocrown, (b) crown with a separate composite core, and (c) overlay without core buildup or pulpal extension. Ten sound teeth were used as control group. All groups were thermocycled (10,000 cycles), subsequently loaded in a chewing simulator (100,000 cycles) and finally loaded until fracture. RESULTS: Peak fracture loads and failure modes were registered. No significant differences were seen between the groups in terms of fracture load. Failure modes were statistically significantly different among groups with significant correlation between restoration type and material. (p < 0.001 and p = 0.033, respectively). No group presented significantly higher fracture resistance. Although ceramic crowns and overlays presented the highest repairability, all restored ETT were within the range of the intact tooth' fracture strength. CONCLUSION: No restoration presented significant different fracture loads. However, the type of restoration and material choice were correlated to the fracture mode.

Fabrication, workflow and delivery of reconstruction: Summary and consensus statements of group 4. The 6th EAO Consensus Conference 2021.

OBJECTIVES: To report assessments of four systematic reviews (SRs) on (i) clinical outcomes of all-ceramic implant-supported crowns (iSCs), (ii) production time, effectiveness, and costs of computer-assisted manufacturing (CAM), (iii) computer-assisted implant planning and surgery (CAIPS) time and costs, and (iv) patient-reported outcome measures (PROMS). MATERIAL AND METHODS: An author group consisting of experienced clinicians and content experts discussed and evaluated the SRs and formulated consensus on the main findings, statements, clinical recommendations, and need for future research. RESULTS: All four SRs were conducted and reported according to PRISMA and detailed comprehensive search strategies in at least three bibliometric databases and hand searching. The search strategies were deemed reproducible. Variation was noted regarding language restrictions and inclusion of grey literature, but the search comprehensiveness appeared persuasive. The SRs included bias risk assessments of the primary studies, and their study methodology impacted the interpretations of the extracted data. CONCLUSIONS: (i) There is limited evidence (49 NRCT) showing that veneered and monolithic all-ceramic iSCs have excellent outcomes observed up to 3 years. (ii) There is no evidence evaluating production time and effectiveness comparing subtractive and additive CAM of implant models, abutments and crowns. (iii) There is limited evidence (4 RCT) that CAIPS involves more time and costs when considering the entire workflow and for diagnostics, manufacturing, and insertion of the restoration. Time seems to be the decisive factor for higher costs. (iv) Patients' comfort increases when optical compared to conventional impressions are used for fabricating iSCs and short-span FPDs (2 RCT, 5 NRCT).

Accuracy of digital impressions of multiple dental implants: an in vitro study.

INTRODUCTION: Studies demonstrated that the accuracy of intra-oral scanners can be compared with conventional impressions for most indications. However, little is known about their applicability to take impressions of multiple implants. AIM: The aim of this study was to evaluate the accuracy of four intra-oral scanners when applied for implant impressions in the edentulous jaw. MATERIAL AND METHODS: An acrylic mandibular cast containing six external connection implants (region 36, 34, 32, 42, 44 and 46) with PEEK scanbodies was scanned using four intra-oral scanners: the Lava C.O.S. and the 3M True Definition, Cerec Omnicam and 3Shape Trios. Each model was scanned 10 times with every intra-oral scanner. As a reference, a highly accurate laboratory scanner (104i, Imetric, Courgenay, Switzerland) was used. The scans were imported into metrology software (Geomagic Qualify 12) for analyses. Accuracy was measured in terms of trueness (comparing test and reference) and precision (determining the deviation between different test scans). Mann-Whitney U-test and Wilcoxon signed rank test were used to detect statistically significant differences in trueness and precision respectively. RESULTS: The mean trueness was 0.112 mm for Lava COS, 0.035 mm for 3M TrueDef, 0.028 mm for Trios and 0.061 mm for Cerec Omnicam. There was no statistically significant difference between 3M TrueDef and Trios (P = 0.262). Cerec Omnicam was less accurate than 3M TrueDef (P = 0.013) and Trios (P = 0.005), but more accurate compared to Lava COS (P = 0.007). Lava COS was also less accurate compared to 3M TrueDef (P = 0.005) and Trios (P = 0.005). The mean precision was 0.066 mm for Lava COS, 0.030 mm for 3M TrueDef, 0.033 mm for Trios and 0.059 mm for Cerec Omnicam. There was no statistically significant difference between 3M TrueDef and Trios (P = 0.119). Cerec Omnicam was less accurate compared to 3M TrueDef (P < 0.001) and Trios (P < 0.001), but no difference was found with Lava COS (P = 0.169). Lava COS was also less accurate compared to 3M TrueDef (P < 0.001) and Trios (P < 0.001). CONCLUSIONS: Based on the findings of this in vitro study, the 3M True Definition and Trios scanner demonstrated the highest accuracy. The Lava COS was found not suitable for taking implant impressions for a cross-arch bridge in the edentulous jaw.

Long-term retrospective follow-up of turned and moderately rough implants in the edentulous jaw.

AIM: To compare the long-term clinical outcome of turned vs. moderately rough implants. MATERIALS AND METHODS: Patients treated with implants in the edentulous mandible and/or maxilla were invited for a clinical examination. After prosthesis removal, the pocket depth was measured and the bleeding scored. Also, a new radiograph was taken for bone loss evaluation. Patients were also requested to rate their satisfaction with the treatment. RESULTS: One hundred and ninety-seven implants in 33 patients were evaluated. After a mean follow-up of 172 months (SD 42, range 120-252), the mean loss was 1.61 mm (SD 1.35, range 0.00-8.25). Bone loss was higher in the maxilla compared to the mandible (P < 0.001), and at implants, that was restored on implant level (P = 0.003). Multivariate analyses demonstrated a significant effect of implant surface roughness and time of loading on bone loss. Smoking, on the other hand, did not affect the outcome. Mean pocket probing depth was 3.64 mm (SD 0.96, range 1.25-7.25). A total of 4.1% of the implants demonstrated signs of peri-implantitis. The overall patient satisfaction rate was 98.5%. CONCLUSION: Implant treatment in the edentulous jaw has a predictable long-term outcome with limited complications.

Fracture resistance of hybrid ceramic abutments with different restoration lengths: A pilot study.

AIM: In this pilot study, the fracture resistance of hybrid abutments with different restoration lengths was investigated. MATERIALS AND METHODS: Sixteen monolithic zirconia restorations of an upper right incisor were designed to fit a titanium base abutment. Eight central incisors had a crown length of 8 mm (T1) and the other half a length of 12 mm (T2). All crowns were cemented on the titanium base using a resin cement. After cementation, the samples were placed in a thermocycler for 5000 cycles. Fracture strength was measured using a universal test machine. Deformations and fractures of the samples were investigated. RESULTS: The mean fracture resistance of T1 was 515 N (SD 96 N, 339-650) and 305 N (SD 57 N, 234-408) for T2 (p < 0.001). Both groups showed deformation of the titanium base, with no significant difference between both groups (p = 0.200). A difference in fracture type (p = 0.013) was observed, with significantly more screw fractures occurring in group T1 (p = 0.026). CONCLUSION: Within the limitations of this study, hybrid restorations with standard titanium base abutments can withstand forces that have been associated with chewing, irrespective of the crown length. However, the shorter crowns demonstrated more fatal fractures.

Complications and Patient Satisfaction in Fully Edentulous Patients Treated with a Digital and Conventional Complete Denture, A Cross-Over Clinical Study.

PURPOSE: The objective of this clinical study was to evaluate comfort, satisfaction, chewing ability and complications with digital complete dentures (DCD) and conventional complete dentures (CCD). MATERIALS AND METHODS: For 16 edentulous patients, two sets of upper and lower dentures were fabricated by students in a university dental clinic. The impression for the DCD was done using indirect scanning of the cast. When the patients were pain free, each set of dentures was worn for four weeks. OHIP-14 and a DSI (Denture Satisfaction Index)were used to measure patient satisfaction and chewing ability respectively. Both questionnaires were administered before fabrication and after wearing each set. Adjustments made during the follow up period were included. At the end of the study, patients could express which set of dentures they preferred. The 25 dental students involved in fabricating the dentures, were questioned in terms of discomfort, preference and future use for both techniques. RESULTS: OHIP-14 showed significantly higher scores for the DCD for the domain concerning psychological discomfort. DSI showed no significant difference for both sets of dentures. In terms of complications, a significant difference was found for occlusion. The DCD required more occlusal adjustments. A minority of the patients (37.5%) chose the DCD as their favourite set. The students preferred the wax try-in and workflow of the CCD. CONCLUSIONS: The CCD and DCD showed differences in patient satisfaction. Chewing ability was comparable for both sets of dentures. More occlusal complications were seen in the DCD. Both students and patients preferred the CCD.

Proof of Concept of a New 3D-Guided System for a Single Implant Overdenture in the Mandible: An In Vitro Study.

PURPOSE: To evaluate the precision and efficiency of a novel guide system for single implant placement in the mandibular symphyses and to evaluate whether the outcome is affected by the level of operator experience. MATERIALS AND METHODS: A total of 90 implants were placed in three different mandibular cast types (Cawood and Howell class III, IV, and V). For each model, a complete denture was 3D printed. A polyether ether ketone rail with a guide sleeve was embedded in the middle of the denture. To determine the ideal implant position, the sleeve could be moved in a buccolingual direction. Adjustment of implant angulation was possible, and an angle correction of 0, 12, or 24 degrees was available. A total of 30 clinicians were divided into three groups: group 1 (experienced, n = 10), group 2 (beginner, n = 10), and group 3 (inexperienced, n = 10). Each clinician was asked to plan and perform a guided flapless implant placement in the mandibular symphysis. Two preoperative CBCT scans were taken; the first was to verify the planning, and the second was to adjust the planning if needed. Finally, a postoperative CBCT scan was taken to compare the planning to the final implant position. RESULTS: Based on the first CBCT, the clinicians adjusted their planning by an average of 1.66 ± 1.65 mm coronally, 2.41 ± 2.44 mm apically, and by a mean angular correction of 6.08 ± 0.77 degrees. After implant placement, the mean deviation from the planned implant position was 0.87 ± 0.58 mm at the coronal aspect and 0.98 ± 0.64 mm at the apical aspect. The mean angular deviation was 6.05 ± 0.71 degrees. Overall, there were no significant differences in coronal and apical deviation (P > .05) based on the level of experience. In terms of angulation, a significant difference was found in both planning (P = .049) and placement (P = .038) between beginners and experienced clinicians. CONCLUSIONS: Guided implant placement of a single implant in the mandibular symphysis using a removable denture with guide sleeve had an acceptable level of accuracy. Clinicians with limited experience spent more time on the procedure, resulting in less angular deviation during implant planning and placement compared to experienced clinicians.

Radiographic evaluation of modern oral implants with emphasis on crestal bone level and relevance to peri-implant health.

Implant stability and maintenance of stable crestal bone level are prerequisites for the successful long-term function of oral implants, and continuous crestal bone loss constitutes a threat to the longevity of implant-supported prosthetic constructions. The prevalence/incidence and reasons for crestal bone loss are under debate. Some authors regard infection (i.e. peri-implantitis) as the cause for virtually all bone loss, while others see crestal bone loss as an unavoidable phenomenon following surgery and implant loading. Irrespective of the cause of continuous crestal bone loss, correct usage and scientifically sound interpretation of radiographs are of utmost importance for evaluation of oral implants. The periapical radiographic technique is currently the preferred method for evaluating implant health based on bone loss, and digital radiographs allow easy standardization of the image contrast. It is suggested that baseline radiographs should be taken at the time the transmucosal part pierces the mucosal tissues and annually thereafter. The number of unreadable radiographs should be presented in scientific publications to give insights into the quality of the radiographic examination. It is suggested that not only mean values, but also the range of bone levels, should be presented to describe the proportion of implants that show continuous crestal bone loss. In the absence of other clinical symptoms, bleeding on probing around implants seems to be a weak indicator of ongoing or future loss of crestal bone. According to recent longitudinal studies on modern implant surfaces peri-implantitis defined as 'infection with suppuration associated with clinically significant progressing crestal bone loss' occurs with a prevalence of less than 5 % in implants with 10 years in function.

Alterations in soft tissue levels and aesthetics over a 16-22 year period following single implant treatment in periodontally-healthy patients: a retrospective case series.

PURPOSE: Long term studies on single implants are scarce and merely focus on clinical response parameters, complications and bone remodelling. The objective of this retrospective case series was to assess alterations in soft tissue levels and aesthetics over a 16-22 year period in periodontally-healthy patients. MATERIAL AND METHODS: Patients who had received a single turned implant in the anterior maxilla/mandible at the Dental Specialist Clinic in Malmö between 1987 and 1993 were invited for a re-examination on the basis of a number of inclusion criteria. Both neighbouring teeth had to be present at re-examination and baseline clinical photographs (within the first year of function) had to be available for soft tissue evaluation. These photographs were superimposed onto final clinical photographs to assess longitudinal soft tissue alterations. RESULTS: Twenty-one patients (nine females; mean age 23, range 16-41) treated with 24 single implants met the criteria for soft tissue evaluation. Peri-implant soft tissue levels (papillae, midfacial level) remained stable over a 16-22 year observation period (p ≥ 0.372). However, neighbouring teeth demonstrated midfacial recession and eruption pointing to a major distortion with the implant crown (> 1 mm) in 5/24 (21%) and 10/24 (42%) of the cases, respectively. Baseline aesthetics was considered poor (mean Pink Esthetic Score 7.42, mean White Esthetic Score 5.43), yet a significant time effect could not be demonstrated (p ≥ 0.552). Implant and tooth bone loss was low (mean 0.6 mm and 0.4 mm, respectively) over a 16-22 year period. CONCLUSIONS: This limited case series demonstrated stable peri-implant soft tissue levels and aesthetics in the long term following single implant treatment in periodontally-healthy patients. However, midfacial recession and eruption may be expected at neighbouring teeth.

The histological evaluation of osseointegration of surface enhanced microimplants immediately loaded in conjunction with sinuslifting in humans.

OBJECTIVE: The aim was to investigate histomorphometrically whether or not implant surface nanotopography improves the bone response under immediate loading simultaneous to sinus grafting. MATERIALS AND METHODS: Dual acid-etched titanium microimplants with/without crystalline surface deposition of calcium phosphate particles were placed in bilateral sinuslift areas grafted with a mixture of iliac crest bone and BioOss. Surface topography of microimplants was characterized using interferometry. Loaded microimplants (MsL) were immobilized in a provisional bridge supported by four normal size implants. Some patients had unloaded microimplants as controls (MsU). Biopsies were trephined after 2 or 4 months and histomorphometric analysis of bone area (BA) and bone-to-implant contact (BC) was performed. Nonparametric methods for dependent data were used to compare effect of surface modification, and healing time (2 vs. 4 months). RESULTS: A total of 53 biopsies were available from 13 patients. A total of 4/28 and 1/11 MsL failed after resp. 2 and 4 months vs. 0/6 and 1/5 MsU. Many loaded biopsies were damaged at the apical portion and showed no bone adhesion. MsL decreased in BA from coronal to apical from 2 to 4 months; Coronal > Middle (P = 0.047), Coronal > Apical (P < 0.001) and Middle > Apical (P < 0.001). This gradual decrease was not observed for BC; Coronal < Middle and Middle > Apical (P < 0.001). Only the middle part showed significant bone contact after 2 months. For MsL there was no statistically significant difference between surface or time indicating that improvement of osseointegration over time due to maturation of the graft was poor. The MsU did not show any difference between Osseotite and Nanotite for BIC and BA (P > 0.05) but doubled both their BA and BIC (P < 0.05) between 2 and 4 months. CONCLUSIONS: Osseointegration in sinus-grafted bone mixed with BioOss was poor irrespective of healing time or nanotopographical surface modification. The apex of MsL showed minimal bone contact suggesting that the graft does not add to the loading capacity. Surface enhancement was not beneficial despite the enlarged surface area. Overloading, most critical coronally of an implant, increases risks for implant failure and jeopardizes bone healing especially under immediate loading conditions with high load.

Comparison of histological and three-dimensional characteristics of porous titanium granules and deproteinized bovine particulate grafts used for sinus floor augmentation in humans: a pilot study.

PURPOSE: Slow-resorbing deproteinized bovine bone grafts have presented high success rates when used for sinus augmentation. However, histologic evaluation shows that this material is eventually excreted as a result of a foreign body reaction. The purpose of this study was to compare and to evaluate the performance of a recently introduced particulate porous graft material, consisting of pure titanium granule (PTG) to the deproteinized bovine bone grafts, when used as a sinus augmentation material. MATERIALS AND METHODS: To understand the histological aspects of PTG, deproteinized bovine particulates (Bio-Oss) and PTG were placed contralaterally as sinus grafting materials in 2 patients. After 9 months, biopsies were performed for histologic and 3-dimensional analysis. RESULTS: Both materials were in contact with newly formed bone. The Bio-Oss showed signs of foreign body reaction. In contrast, bone filled the space between the single PTG particulates, and no foreign body reaction was observed. CONCLUSIONS: From a bone formation perspective, PTG grafts were comparable with the commonly used Bio-Oss grafts and may be regarded as a possible alternative for permanent grafting in sinus augmentation.

Histomorphometry and bone mechanical property evolution around different implant systems at early healing stages: an experimental study in dogs.

PURPOSE: Commercial implants differ at macro-, micro-, and nanolevels, which makes it difficult to distinguish their effect on osseointegration. The aim of this study was to evaluate the early integration of 5 commercially available implants (Astra OsseoSpeed, Straumann SLA, Intra-Lock Blossom Ossean, Nobel Active, and OsseoFix) by histomorphometry and nanoindentation. MATERIALS AND METHODS: Implants were installed in the tibiae of 18 beagle dogs. Samples were retrieved at 1, 3, and 6 weeks (n = 6 for each time point) and were histologically and nanomechanically evaluated. RESULTS: The results presented that both time (P < 0.01) and implant system and time interaction (P < 0.02) significantly affected the bone-to-implant contact (BIC). At 1 week, the different groups presented statistically different outcomes. No significant changes in BIC were noted thereafter. There were no significant differences in rank elastic modulus (E) or in rank hardness (H) for time (E: P > 0.80; H: P > 0.75) or implant system (E: P > 0.90; H: P > 0.85). CONCLUSIONS: The effect of different implant designs on osseointegration was evident especially at early stages of bone healing.

Accuracy of a chairside reverse scanbody workflow for a complete arch implant-supported prosthesis using four intraoral scanners versus a desktop scanner.

OBJECTIVES: The aim of this study was to evaluate the accuracy of a chairside reverse scanbody workflow for a complete arch implant-supported prosthesis using four intraoral scanners (IOSs) and a desktop scanner. MATERIAL AND METHODS: A complete arch implant-supported interim prosthesis was designed and milled in polymethylmethacrylate. Six reverse scanbodies (ScAnalog) were connected to the implant-prosthetic connections and twenty scans were made extraorally using four IOS devices (TRIOS 3, TRIOS 5, Primescan v.5.2, Medit i700W) and one desktop scanner (E4 RED). A coordinate machine (ATOS Q GOM) was used to assess the milling distortion. The scanbody positions were compared to the reference CAD design using metrology software. Linear and angular measurements per implant-prosthetic connection were considered for trueness and precision. Data were analyzed using one-way ANOVA and Bonferroni test. RESULTS: Trueness values were 118.14 ± 25.49 µm for TRIOS 3, 84.62 µm ±19.10 for TRIOS 5, 106.39 ± 27.58 µm for Primescan v.5.2, 120.25 ± 27.44 µm for Medit i700W and 65.36 ± 4.66 µm for E4 RED. Significant differences in mean trueness values were found among IOS and E4 RED. Precision values were 108 ± 55 µm for TRIOS 3, 86 ± 55 µm for TRIOS 5, 104 ± 55 µm for Primescan v.5.2, 90 ± 54 µm for Medit i700W and 18 ± 11 µm for E4 RED. Significant differences in precision were found between IOS and E4 RED. CONCLUSIONS: A chairside reverse scanbody workflow with IOS remains less accurate compared to similar workflow with a desktop scanner. CLINICAL SIGNIFICANCE: A chairside reverse scanbody workflow is a valuable alternative but the IOS device should be selected with caution because in the present study, only TRIOS5 was capable to achieve an accuracy below the clinical acceptable thresholds. The use of a desktop scanner remains the best choice for this clinical workflow. Additionally, the milling distortion of the interim prosthesis plays a major role in this reverse scanbody workflow and should be kept as low as possible.

Five years clinical outcome of maxillary mini dental implant overdenture treatment: A prospective multicenter clinical cohort study.

BACKGROUND: The long-term clinical outcome of mini dental implants (MDIs) to support an overdenture is underreported especially in severely atrophic maxillae and when installed flaplessly. PURPOSE: The current report is a 5-years follow-up of the previously published 2- and 3-years clinical outcome of MDIs supporting a maxillary overdenture in narrow alveolar ridges. MDI survival, marginal bone level, peri-implant health, technical complications, and oral health related quality of life (OHIP) and respective changes over time are reported. MATERIALS AND METHODS: Subjects aged 50 years or older, in need of improvement of maxillary denture retention, were included. The MDIs were 2.4 mm diameter one-piece tapered implants, Class 4 pure Titanium, and lengths 10 or 11.5 mm. Under local anesthesia, 5-6 MDIs were placed in atrophic maxillae with a free-handed flapless approach. One week postoperative the denture was adapted with a retentive soft reliner. The final prosthetic connection was established after 6 months with a metal-reinforced horse-shoe denture. Clinical outcome after 5 years was assessed with probing pocket depts (PPD), bleeding on probing (BoP), and additional cone beam computed tomography (CBCT) MDI bone level measurements were performed. Oral Health-Related Quality of Life (OHRQoL) investigated with OHIP-14 was assessed preoperative, during provisional loading, and after final prosthetic connection up to 5 years. RESULTS: Initially, 31 patients (14 females and 17 males) with mean age 62.30 underwent treatment. In the provisional loading interval, 16 patients encountered 32/185 MDIs failures, resulting in a failure of 17.3%; 170 MDIs were functionally loaded in 29 patients. Additionally, 14 implants were lost in three patients, all of whom had had already previous failures. Reimplantation of 17 MDIs were performed during the provisional loading and 2 MDI after functional loading. After 5 years, the absolute implant failure rate was 46/204 (22.5%), corresponding to a cumulative failure rate of 23.2%. Prosthetic failure was observed in four patients due to implant loss and in two patients related to excessive one-piece implant ball attachment wear, making the 5-years prosthetic success 80.0%. The mean PPD and absence/presence of BoP for 149 implants at 5 years was 4.3 and 0.2 mm, respectively. Average mesial-distal-vestibular-palatal bone loss in the interval 2-5 years was 0.08 mm. No statistically significant difference in marginal MDI bone loss between male or female (p = 0.835), smoking and nonsmoking (p = 0.666) was observed. The five-years total measured CBCT interdental bone level (mesial and distal) correlates with the 5-years PPD (Pearson 0.434; p = 0.01). After 5 years, OHRQoL with the treatment procedure was assessed in 27/31 participants. Decreasing mean total OHIP-14 scores with improved OHRQoL, was observed in 27/31 participants, with values of 21.3 at baseline to 15.6 at the time of provisional loading which significantly (p = 0.006) decrease to 7.3 at the final prosthetic connection. The next 3-5 years further decrease was observed with 6.5 and 4.96, respectively. CONCLUSIONS: Maxillary MDIs for overdentures are an accessible and acceptable treatment option. Although after 5 years between one fifth and one fourth of the MDIs were lost, prosthetic success remains 80.0% and high OHRQoL could be achieved.

The effect of smoking on survival and bone loss of implants with a fluoride-modified surface: a 2-year retrospective analysis of 1106 implants placed in daily practice.

AIM: To compare the survival and peri-implant bone loss of implants with a fluoride-modified surface in smokers and nonsmokers. MATERIALS AND METHODS: Patient files of all patients referred for implant treatment from November 2004 to 2007 were scrutinized. All implants were placed by the same experienced surgeon (B. C.). The only inclusion criterion was a follow-up time of at least 2 years. Implant survival and bone loss were assessed by an external calibrated examiner (S. V.) comparing digital peri-apical radiographs taken during recall visits with the post-operative ones. Implant success was determined according to the international success criteria (Albrektsson et al. 1986). Survival of implants installed in smokers and nonsmokers was compared using the log-rank test. Both nonparametric tests and fixed model analysis were adopted to evaluate bone loss in smokers and nonsmokers. RESULTS: One-thousand one-hundred and six implants in 300 patients (186 females; 114 males) with a mean follow-up of 31 months (SD 7.15; range 24-58) were included. Nineteen implants in 17 patients failed, resulting in an overall survival rate of 98.3% at the implant level and 94.6% at the patient level. After a follow-up period of 2 years, the cumulative survival rates was 96.7% and 99.1% with the patient and implant as the statistical unit, respectively. Implant survival was significantly higher for nonsmokers compared with smokers (implant level P=0.025; patient level P=0.017). The overall mean bone loss was 0.34 mm (n=1076; SD 0.65; range 0-7.1). Smokers lost significantly more bone compared with nonsmokers in the maxilla (0.74 mm; SD 1.07 vs. 0.33 mm; SD 0.65; P<0.001), but not in the mandible (0.25 mm; SD 0.65 vs. 0.22 mm; SD 0.5; P=0.298). CONCLUSION: The present study is the first to compare peri-implant bone loss in smokers and nonsmokers from the time of implant insertion (baseline) to at least 2 years of follow-up. Implants with a fluoride-modified surface demonstrated a high survival rate and limited bone loss. However, smokers are at a higher risk of experiencing implant failure and more prone to show peri-implant bone loss in the maxilla. Whether this bone loss is predicting future biological complications remains to be evaluated.

Reliability and Time Efficiency of Digital vs. Analog Bite Registration Technique for the Manufacture of Full-Arch Fixed Implant Prostheses.

OBJECTIVE: Information about full-digital protocols for bite registration with intraoral scanners on multiple implants in the edentulous jaw is scarce. The purpose of this comparative in vivo study was to investigate the reliability and time efficiency of a novel full-digital bite registration technique for the manufacture of full-arch maxillary fixed implant prostheses. MATERIAL AND METHODS: In ten patients, a full-arch maxillary fixed implant prosthesis was manufactured on multi-unit abutment level through an analog prosthetic workflow. The bite registration was performed with use of a screw-retained polymethyl methacrylate (PMMA) verification jig with detachable wax rim. To articulate the definitive edentulous maxillary implant cast in centric relation at the appropriate occlusal vertical dimension (OVD) to the mandibular antagonist cast, a type II articulator (Artex, Amann Girrbach) was used. Three to six months later, a full-digital bite registration was performed with use of dual-function scan bodies and bilateral connected bite pillars. The bite pillars screwed into the scan bodies were used to adjust and articulate the edentulous maxillary implant arch to the mandibular antagonist arch at the defined OVD. Treatment time for analog and digital bite registration technique was measured in each patient. The reliability of the digital bite registration technique was evaluated by 3D comparison of two sets of stereo lithographic (STL) files obtained from each patient. The three-dimensional deviation was defined along the X-, Y- and Z-axes (Geomagic Control X, 3D Systems Inc., Rock Hill, SC, USA). RESULTS: The treatment time for digital bite registration using dual-function scan bodies and bite pillars was significantly shorter than analog bite registration with verification jig and wax rim (60.30%, SD 5.72%). Minor differences between the two techniques were observed with a linear deviation range of 1115 µm (SD 668 µm) overall, 46.2 µm (SD 731.3 µm) along the X-axis, -200.3 µm (SD 744.3 µm) along the Y-axis and 67.1 µm (SD 752.2 µm) along the Z-axis. Bilateral balanced contacts were registered in all patients during full-digital bite registration. CONCLUSIONS: The novel digital bite registration technique with dual-function scan bodies and bite pillars allows for a full-digital workflow for full-arch implant supported restorations. The digital bite workflow was 60% faster, and the overall deviation was around 1 mm, which can be considered clinically acceptable.

In Vitro Accuracy of Digital and Conventional Impressions for Full-Arch Implant-Supported Prostheses.

The aim of this study was to evaluate the accuracy of full-arch digital impressions when compared to conventional impressions, when performed on the abutment or implant level. METHODS: One resin cast with six implants and another cast with six abutments were scanned with Primescan v5.1 (PS51), Primescan v5.2 (PS52), Trios 3 (T3), and Trios 4 (T4). Additionally, conventional impressions (A) were made, poured in gypsum, and digitized using a lab scanner (IScan D104i). A coordinate machine (Atos, GOM, Braunschweig, Germany) was used to generate the reference scan of both casts. For all scans, the position of the implants was calculated and matched with the reference scan. Angular and coronal measurements per implant were considered for trueness and precision. RESULTS: For the implant-level model, PS52 performed significantly better in terms of trueness and precision compared to all other impressions, except for the angular trueness of A (p = 0.072) and the coronal trueness of PS51 (p = 1.000). For the abutment-level model, PS52 also performed significantly better than all other impressions, except for the coronal trueness and precision of A (p = 1.000). CONCLUSIONS: Digital impressions for full-arch implant supported prostheses can be as accurate as conventional impressions, depending on the intra-oral scanner and software. Overall, abutment level impressions were more accurate compared to implant level impressions.

A Completely Digital Workflow for Nanoceramic Endocrowns: A 5-Year Prospective Study.

PURPOSE: To evaluate the success of monolithic endocrowns fabricated using a digital workflow. MATERIALS AND METHODS: Twenty-three patients requiring restoration of devitalized molars or premolars were included in the study. The preparation was scanned using an intraoral scanner (Cerec Bluecam, Dentsply Sirona), and a monolithic restoration was made from a nanoparticle resin-based hybrid composite (#10 Cerasmart [CS]; #10 Lava Ultimate [LU], 3M Espe) or a polymer-infiltrated ceramic (#10 Vita Enamic [VE]). At the time of placement and after 6 months, 1 year, and 5 years of function, radiographs were taken to evaluate the marginal integrity of the restorations, and clinical pictures were taken to assess the quality of the restoration using the USPHS criteria. RESULTS: After 5 years, the restorative success rate was 70.8%, the restorative survival rate was 87.5%, and the tooth survival was 91.6%. Four chippings (two LU, two CS), three fractures (three LU), and two debonding of the restorations (two CS) occurred. Also, two teeth were extracted after 5 years of follow-up (two VE) because of secondary caries and a root fracture. The USPHS ratings were high, except for color match, which was rated the lowest at all time intervals. CONCLUSION: Nanoceramic endocrowns made using a completely digital workflow have an acceptable survival rate after 5 years. However, the complication rate was high.

Accuracy of Guided Implant Surgery Using an Intraoral Scanner and Desktop 3D-Printed Tooth-Supported Guides.

PURPOSE: The increasing popularity of desktop 3D printers makes guided surgery more accessible. The aim of this in vitro study was to evaluate the accuracy of single-tooth guided implant surgery by means of a 3D-printed tooth-supported guide. MATERIALS AND METHODS: Fifteen implants were virtually planned to replace a missing first mandibular molar, using planning software for guided implant surgery (Exoplan, Exocad). A tooth-supported guide was designed and manufactured using a desktop 3D printer (Asiga MAX UV). The implants were placed fully guided in resin casts, and a digital impression was taken to register their position. This scan was compared with the virtual implant position in the planning software, and the internal fit of the guides was evaluated using metrology software. One planning was executed six times for measuring precision. RESULTS: For trueness, the mean angular deviation was 2.63 degrees (SD: 1.69 degrees; range: 0.38 to 5.99 degrees), the mean coronal deviation was 0.52 mm (SD: 0.25; range: 0.09 mm to 1.07 mm), and the mean apical deviation was 0.90 mm (SD: 0.47; range: 0.14 to 1.74 mm). The absolute apical mean deviation in the buccolingual direction (x-axis) was 0.70 mm (SD: 0.42, 0.12 to 1.65 mm; P < .001); in the mesiodistal direction (y-axis), it was 0.34 mm (SD: 0.26; range: 0.01 to 0.80 mm; P = .650); and in the vertical direction (z-axis), it was 0.32 mm (SD: 0.27; range: 0.02 to 1.00 mm; P = .010). The mean internal fit of the guides was 79.5 µm (SD: 19.6 µm; range: 51 to 118 µm). CONCLUSION: Desktop 3D-printed tooth-supported guides demonstrate an acceptable fit and acceptable level of accuracy for single implant placement.

A wide-body implant as an alternative for sinus lift or bone grafting.

PURPOSE: The aim was to evaluate the outcome of a short wide-body implant in the atrophic posterior jaw without a grafting procedure. MATERIALS AND METHODS: Patients treated with a tapered wide-body implant measuring 8 to 9 mm in width and 7 to 9 mm in length (Max implant; Southern Implants, Irene, South Africa) were recalled to scrutinize implant survival. Preoperative cone beam computed tomography images were analyzed to measure bone height in reference to the mandibular canal and sinus floor. RESULTS: There were 57 implants inserted in 18 men and 24 women after a 2-stage procedure and delayed loading. The mean follow-up was 15 months (SD, 10; range, 1-32 months), with 63.2% of the implants having at least 1 year of follow-up and 26.3% having at least 2 years' follow-up. Forty-six implants were inserted in the posterior maxilla and eleven in the mandible. Fifteen were placed in an extraction socket and forty-two in healed bone. Thirteen implants were supporting a single crown. Two implants failed, resulting in a survival rate of 96.5%, with rates of 90.9% and 97.8% for mandible and maxilla, respectively. This was not affected by gender, jaw, immediate or delayed placement, implant diameter and length, or the use of a bone substitute. The mean preoperative bone height was 7.21 mm in maxilla and 8.76 mm in mandible. In 41 cases implant length surpassed available bone height. CONCLUSIONS: Despite the compromised bone condition and height, the survival rate of 96.5% is comparable to normal implants and, therefore, placing a wide-body implant may be an alternative to avoid grafting procedures. This is probably related to the enlarged implant surface area and the good primary stability.