Maxillary and mandibular overdentures retained by two unsplinted narrow-diameter titanium-zirconium implants - A clinical pilot study.

OBJECTIVES: To evaluate the survival rates and marginal bone loss of narrow-diameter titanium-zirconium implants supporting complete maxillary and mandibular overdentures up to 3 years after loading. MATERIALS AND METHODS: Ten completely edentulous patients who were dissatisfied with their complete dentures were enrolled. Two narrow-diameter implants were placed in the canine region of the maxilla and mandible. After second-stage surgery, implant-supported overdentures (palatal-free) attached by parallel alignable stud-attachments were placed. Patients were followed periodically for up to 36 months. Standardized radiographs were taken at baseline, 12 and 36 months to analyze mean marginal bone level changes around the implants. RESULTS: The Kaplan-Meier survival rates were 100% for mandibular and 68.0% (SE ± 10.9%) for maxillary implants at 36 months (p = .008). Six maxillary implants failed after loading; no mandibular implants were lost. Five implants failed due to loss of osseointegration. One implant fractured. The mean marginal bone level changes around the analyzed implants (n = 28, 9 patients) were -0.71 ± 0.82 mm in the mandible and -2.08 ± 1.52 mm in the maxilla at the 36-month follow-up. The difference in marginal bone level changes between the maxilla and mandible was significant (p = .019) at the 12- and 36-month follow-ups. CONCLUSION: Two narrow-diameter titanium-zirconium implants with stud-attachments showed a highly satisfactory outcome in the mandible. The maxillary implants showed a high failure rate and significantly more bone loss over time than the mandibular implants. The minimal concept of two implants and an overdenture should be limited to the edentulous mandible.

Functionalization of a zirconia surface by covalently immobilized fibronectin and its effects on resistance to thermal, acid, and mechanical exposure.

Silane chemistry has emerged as a powerful tool for surface modification, offering a versatile means to enhance the properties of various substrates, such as dental implant abutment materials. In this study, we investigated the stability of the 3-aminopropyldiisopropylethoxysilane (APDS) layer on yttria-partially stabilized zirconia (Y-TZP) surfaces after mechanical, acid, and thermal treatment in order to simulate fluctuations within the oral cavity. To accomplish that, the viability of human gingival fibroblasts on APDS-modified surfaces after applied treatment strategies was assessed by live/dead staining. Moreover, the hydrolysis stability and enzymatic degradation resistance of crosslinked fibronectin to the APDS layer was examined by immunostaining and western blot. The results revealed that the applied modifications were not affected by the different treatment conditions and could withstand the fluctuations in the oral cavity. Furthermore, crosslinked fibronectin on silanized Y-TZP was stable against hydrolysis over 21 days and enzymatic degradation. We thus can conclude that the proposed functionalization method has high potential to tolerate harmful effects within the oral cavity and remains unchanged on the surface.

Assessment and evaluation of a serious game for teaching factual knowledge in dental education.

OBJECTIVES: A serious game application was developed to train factual knowledge and for self-assessment. The aim of the present study was to compare the effects of a game application (intervention group) or paper scripts (control group) on knowledge acquisition and to evaluate the acceptance of the new application among dental students. METHODS: The 4th semester students of the second preclinical prosthodontics course were randomly assigned to one of the two groups (n = 58/51) for two consecutive years. The study was conducted in two phases: First, all participants took a pretest, with the intervention group using the game application and the control group receiving the same set of questions in a paper script. In the second phase, all participants took a post-test. After the post-test, both groups had access to the application for another three weeks. After that, all participants completed standardized questionnaires and a scale to evaluate the usability of the system. Usage statistics were also tracked. Differences between groups were evaluated together and for both years separately in terms of pretest and posttest scores and learning success. RESULTS: There was no significant difference between the groups with regard to the posttest and learning success. A significant improvement in knowledge between pretest and posttest (p < 0.05) was demonstrated in both groups. Each student played approximately 350 questions. Participants rated the application with the German school grade "good". Participants appreciated the application and rated it positively. They stated that the game motivated them to learn and that they spent more time with the learning content. CONCLUSION: Due to the positive perception achieved through the game, this application is able to motivate students to learn. The learning effect achieved is similar to learning on paper.

Effect of Er,Cr:YSGG laser with a side-firing tip on decontamination of titanium disc surface: an in vitro and in vivo study.

PURPOSE: To evaluate the effectiveness of an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser with side-firing tip in decontamination of titanium (Ti) disc. METHODS: In the first test series, 29 Ti-discs were contaminated with Staphylococcus aureus and treated as follows: positive control (no treatment); Perioflow; Laser A (0.75 W, 100 Hz), Laser B (1.5 W, 30 Hz); Laser C (no radiation, 60% water); and Laser D (no radiation, 50% water). For bacterial quantification, colony forming units (CFU, vital cells only) and quantitative PCR (qPCR, vital and devital cells) were performed. In a second test series, 92 Ti-discs were used, contaminated with in vivo-grown biofilm and treated as follows: positive control (no treatment); Perioflow; Laser E (1.5 W, 30 Hz), and Laser F (no radiation, 50% water). Considering the different and unknown culture conditions, quantification of bacteria was performed by broad-spectrum bacterial qPCR only. Based on the assumption that all cells of an organism contain an equivalent complement of genetic information, genome equivalent (GE) determination ensured the detection of the different intact and semi-intact genomes, regardless of type of bacterial species and vitality, circumvent the inherent bias of cultures. RESULTS: The GE values were significantly reduced by all interventions in both test series, compared to the positive control group (p < 0.001). In the first test series with S. aureus as model organism, Perioflow yielded a lower GE than the Laser groups A-D (all p < 0.025). The number of CFUs was significantly reduced in the intervention groups compared to the positive control (p < 0.001), except for Laser A (p = 0.157) and Laser D (p = 0.393). In the second test series, none of the pairwise comparisons of the intervention conditions showed a significant difference (Perioflow vs. Laser E: p = 0.732; Perioflow vs. Laser F: p = 0.590; Laser E vs. Laser F: p = 0.379). CONCLUSION: The Er,Cr:YSGG laser with side-firing tip and Perioflow were equally capable of effectively decontaminating a Ti-disc surface. It is assumed that the bacterial reduction was largely due to the mechanical effect of the air and water stream.

HOW TO IDENTIFY SUBGROUPS IN LONGITUDINAL CLINICAL DATA: TREATMENT RESPONSE PATTERNS IN PATIENTS WITH A SHORTENED DENTAL ARCH.

BACKGROUND: When dental patients seek care, treatments are not always successful,that is patients' oral health problems are not always eliminated or substantially reduced. Identifying these patients (treatment non-responders) is essential for clinical decision-making. Group-based trajectory modeling (GBTM) is rarely used in dentistry, but a promising statistical technique to identify non-responders in particular and clinical distinct patient groups in general in longitudinal data sets. AIM: Using group-based trajectory modeling, this study aimed to demonstrate how to identify oral health-related quality of life (OHRQoL) treatment response patterns by the example of patients with a shortened dental arch (SDA). METHODS: This paper is a secondary data analysis of a randomized controlled clinical trial. In this trial SDA patients received partial removable dental prostheses replacing missing teeth up to the first molars (N = 79) either or the dental arch ended with the second premolar that was present or replaced by a cantilever fixed dental prosthesis (N = 71). Up to ten follow-up examinations (1-2, 6, 12, 24, 36, 48, 60, 96, 120, and 180 months post-treatment) continued for 15 years. The outcome OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP). Exploratory GBTM was performed to identify treatment response patterns. RESULTS: Two response patterns could be identified - "responders" and "non-responders." Responders' OHRQoL improved substantially and stayed primarily stable over the 15 years. Non-responders' OHRQoL did not improve considerably over time or worsened. While the SDA treatments were not related to the 2 response patterns, higher levels of functional, pain-related, psychological impairment in particular, and severely impaired OHRQoL in general predicted a non-responding OHRQoL pattern after treatment. Supplementary, a 3 pattern approach has been evaluated. CONCLUSIONS: Clustering patients according to certain longitudinal characteristics after treatment is generally important, but specifically identifying treatment in non-responders is central. With the increasing availability of OHRQoL data in clinical research and regular patient care, GBTM has become a powerful tool to investigate which dental treatment works for which patients.

Long-term outcome of the IMZ implant system: a retrospective clinical study with a follow-up between 23 and 34 years.

PURPOSE: To evaluate the radiographic and peri-implant outcomes of intramobile cylinder implants (IMZs) and the feasibility of long-term follow-up studies after nearly 30 years. METHODS: Of the 94 patients treated with IMZ implants between 1981 and 1995, 39 patients were successfully contacted (contact group, CG), of which 15 patients with a total of 32 implants agreed to participate in the present follow-up study (clinical evaluation group, CEG). The overall implant survival rate was calculated. Information on implant status and oral and general health data was collected. Marginal bone level was evaluated and then compared to the patients' baseline data. Possible risk factors for peri-implantitis were also identified. RESULTS: In total, 16 implants in seven patients were lost, amounting to an overall survival rate of 79.5% after 30 years with a mean follow-up time of 24 ± 10 years (CG). Eight patients were treated with bar-retained mandibular overdentures and seven patients had fixed partial dentures. After a mean observation time of 29 ± 3 years, the surviving implants showed a peri-implantitis rate of 9.4% with a mean marginal bone loss of 2.5 ± 1.8 mm (CEG). No significant correlation between peri-implantitis and possible risk factors could be found. CONCLUSIONS: Long-term follow-up studies with acceptable response rates after nearly 30 years are not feasible. Contact was only possible with 41% of the patients. This contact group showed a high implant survival rate. Due to the retrospective study design, additional risk factors could not be considered in a conclusive analysis.

SafetyCrown: a patient-centered, fully digital concept for immediate implant restoration following the one-abutment/one-time concept-a pilot case series of a new treatment concept.

INTRODUCTION: The patient-centered SafetyCrown-workflow enables the immediate restoration of posterior missing teeth and short free-end situations following one-abutment/one-time within three visits and only one surgical approach. This prosthodontic rehabilitation aims to combine the advantages of cemented and screw-retained restorations. REPORT: The concept has been performed with 4 restorations in 3 patients and followed up for up to 1 year (mean: 11.2 months) without technical and/or biological complication. Visit 1: Intraoral optical impression, CBCT, and tooth shade selection. Virtual implant planning is performed, and a surgical guide is printed. After exporting the planned implant position, a tooth-colored abutment is fabricated from zirconia with a 1-mm supragingival cementation line, adhesively bonded to a titanium base. Visit 2: Fully navigated implant placement with insertion of the definitive abutment. Subsequently, optical impressions are prepared for A: immediate restoration using a PMMA crown without functional contacts; B: definitive crown fabricated from monolithic zirconia and individualized. The localization of the screw channel is marked using stain thus permitting precise screw channel access, if necessary. Visit 3: After osseointegration of the implant, the definitive crown is adhesively cemented supragingival. In a retrospective analysis of PROMs ('How stressful was the treatment process […]?' (0 = not stressful at all, 100 = very stressful), mean VAS score for SafetyCrown of 14 (SD 11.7) and 29.8 (SD 23.1) for standard procedure were present. CONCLUSION: The SafetyCrown offers a shortened, patient-oriented concept for implant-supported single-tooth reconstructions omitting second-stage surgery. Clinical performance and hypothesized prosthodontic benefits require confirmation via an RCT.

Effect of different dental implant drilling template designs on heat generation during osteotomy - an in vitro study.

OBJECTIVES: This in vitro study examined the effect of different implant drilling template designs on heat generation during osteotomy and on cooling fluid distribution. MATERIAL AND METHODS: Five different template designs were investigated in a standardized setup against a control group and a negative control group: Occlusal-splint-design (OSD), OSD-covering, OSD-lateral opening, Bar design, and Orientation template. Pilot and one consecutive drill were run at 800 rpm with external irrigation and 2-kg load. Thermocouples recorded temperature changes at depths of 3, 6, and 9 mm in a bovine rib model. In the second experimental setup, the drill channel of one rib sample was perforated, and the irrigation volume passing through the drill channel was collected separately over time. RESULTS: Following mean temperature rises occurred [in °C]: control, 4.9; negative control, 12; OSD, 5.6; OSD-covering, 4.7; OSD-lateral opening, 3.8; Bar design, 5.1; and Orientation template, 4.9. The highest temperature increases were found at a drilling depth of 6 mm (p < .006). The 2.2-mm drill resulted in a significantly higher temperature rise than the 2.8-mm drill (p < .001). The mean volume (ml/min) of irrigation through the drill channel was Control group-flow, 28.5; OSD, 4.1; OSD-covering, 2; OSD-lateral opening; 5.8; bar design, 4; and Orientation template, 24.1. CONCLUSION: Within the limitations, it was shown that fully guided drilling templates reduce the amount of cooling liquid at the point of osteotomy. The template design had an influence on the effective volume of the cooling liquid. However, this did not seem to increase the intraosseous temperature significantly.

Efficacy of rehabilitation with different approaches of implant-supported full-arch prosthetic designs: A systematic review.

AIM: To evaluate the efficacy of different types of rehabilitation with fixed or removable full-arch implant-supported prosthesis designs in terms of implant loss and success in patients with at least one edentulous jaw, with tooth loss mainly due to periodontitis. MATERIALS AND METHODS: Clinical studies with at least 12 months reporting on implant loss and implant success were searched. Meta-analysis was conducted to estimate cumulative implant loss considering different prostheses designs. RESULTS: A total of 11 studies with unclear to low risk of bias were included in the analysis. Estimated cumulative implant loss for fixed prostheses within 1 year and 5 years was 0.64% (95% confidence interval [CI]: 0.31%-1.31%) and 1.85% (95% CI: 0.85%-3.95%), respectively. The corresponding values for removable prostheses amounted to 0.71% (95% CI: 0.22%-2.28%) and 4.45% (95% CI: 2.48%-7.85%). Peri-implantitis affected 10%-50% of the patients restored with implant-supported fixed prostheses. CONCLUSIONS: Based on the limited low-quality data, the present analysis points to a low and similar cumulative implant loss within 1 year for patients with tooth loss mainly due to stage IV periodontitis restored with either removable or fixed implant-supported full-arch prosthesis. At 5 years of functioning, there was a tendency for better outcomes using fixed designs.

IMPACT OF SHORTENED DENTAL ARCH ON ORAL HEALTH-RELATED QUALITY OF LIFE.

BACKGROUND: A shortened dental arch (SDA) is an established treatment concept for patients with missing molars. However, little is known regarding long-term course of oral health-related quality of life (OHRQoL) in patients with SDA and the benefits from replacement of missing molars. OBJECTIVE: Purpose of this multi-center randomized clinical trial was to assess OHRQoL over a period of 15 years in patients with molar replacement by a removable partial denture (RPD) compared to patients with a restored SDA without molar replacement. METHODS: Patients at least 35 years of age with all molars missing in 1 jaw and at least the canine and one premolar present on each side were included. Patients received either a precision attachment-retained, RPD for replacement of missing molars (n = 79), or the dental arch ended with the second premolar (SDA) that had to be present or replaced by a cantilever fixed dental prosthesis (n = 71). Follow-up examinations continued for 15 years. OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP). OHIP summary and dimension scores were longitudinally modeled in the statistical analyses to assess course of OHRQoL over time applying an intention-to-treat approach. In addition, scores for the OHRQoL dimensions Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact were analyzed. RESULTS: After an initial improvement in OHRQoL indicated by a mean decrease of 20.0 OHIP points with an effect size of 0.61 in the entire study population, OHRQoL stayed relatively constant over the entire follow-up period. Assuming a constant time and treatment effects over the study period, OHRQoL did not differ statistically significant between the 2 treatments (0.4 OHIP points; 95%-CI: 7.1 - 6.2). OHRQoL after treatment did not change notably over 15 years and was statistically nonsignificant as well (P = .872). Similar findings were observed in all 4 OHRQoL dimensions. CONCLUSIONS: In patients, missing all molars in one jaw OHRQoL improved providing RPD or restoring SDA to a clinically relevant degree. Treatment-related improvement remained mostly stable over a period of at least 15 years. Therefore, patients can be informed that both treatment concepts are equivalent concerning long-term OHRQoL. Accordingly, patients' preferences regarding treatment options should be granted priority in treatment decision making with the SDA treatment option being the default.

Patient-reported outcome measures (PROMs) of implant-supported reconstructions using digital workflows: A systematic review and meta-analysis.

OBJECTIVES: To summarize the existing evidence on patient-reported outcome measures (PROMs) of implant-supported restorations fabricated using a digital workflow in comparison to conventional manufacturing procedures. METHODS: A PICO strategy was executed using an electronic and manual search focusing on clinical studies evaluating PROMs of implant-supported restorations. Only clinical trials assessing conventional versus digital workflows for implant-supported restorations were included. PROMS on implant impression procedures and fabrication of final restorations were evaluated using random and fixed effects meta-analyses, while implant planning/placement was reported descriptively. RESULTS: Among 1062 titles identified, 14 studies were finally included, and only seven studies were eligible for meta-analysis. For implant planning and placement, only a qualitative analysis was possible due to heterogeneity between the studies. For impression procedures, the random effects model revealed statistically significant differences in taste, anxiety, nausea, pain, shortness of breath, and discomfort in favor of optical impressions. No significant difference in the subjective perception of the duration of an impression could be reported. For the final fabrication of restorations, no significant difference between veneered and monolithic posterior restorations was found in terms of esthetic, function, and general satisfaction. CONCLUSION: Most of the studies reporting about PROMs were published during the last ten years and limited to implant-supported single crowns in the posterior region. Based on PROMs, no scientifically proven recommendation for guided implant placement could be given at this time. Patients showed high preference for optical impressions, whereas no differences between veneered and monolithic restorations could be reported.

Cemented versus screw-retained posterior implant-supported single crowns: A 24-month randomized controlled clinical trial.

OBJECTIVES: To compare the incidence of biological and technical complications of cemented and screw-retained monolithic lithium-disilicate implant-supported posterior single crowns. MATERIAL AND METHODS: Forty-one subjects with a total of 56 implants received randomly allocated 28 cemented and 28 screw-retained crowns. In the screw-retained group, monolithic lithium-disilicate restorations were luted to titanium bases extraorally. In the cemented group, monolithic lithium-disilicate crowns were cemented on individualized titanium abutments intraorally. All restorations were examined according to modified FDI criteria within 2 weeks of inserting the crowns (baseline) and after 12 (n = 46) and 24 (n = 43) months. Bone loss was evaluated by standardized radiographs at baseline and 12 months. RESULTS: After 12 months, the incidence of mucositis (positive bleeding on probing) was 14.2% (screw-retained) and 17.9% (cement-retained). The gingival and plaque index and a mean marginal bone loss between 0.03-0.15 mm showed no significant difference between the groups. In the cemented group, cement residues were detected at baseline at two restorations (6.9%) by radiographic examination. A complete digital workflow was realized in most cases (85.7%). At 24 months, no restoration had failed, and no chipping of the ceramic had occurred. In the screw-retained group, screw loosening occurred in one implant. In both groups, there was obvious deterioration in the quality of 32% of the occlusal and of 18% of the proximal contact points. CONCLUSIONS: The type of retention mode of monolithic implant-retained lithium-disilicate posterior crowns had no influence on the biological and technical complication rate.

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).

Identification of dental pain sensation based on cardiorespiratory signals.

The aim of this study is to investigate the feasibility of the detection of brief periods of pain sensation based on cardiorespiratory signals during dental pain triggers. Twenty patients underwent dental treatment and reported their pain events by pressing a push button while ECG, PPG, and thoracic effort signals were simultaneously recorded. Potential pain-indicating features were calculated from the physiological data (sample length of 6 s) and were used for supervised learning of a Random forest pain detector. The best feature combination was determined by Feature forward selection. The best feature combination comprises nine feature groups consisting of four respiratory and five cardiac related groups. The final algorithm achieved a sensitivity of 87% and a specificity of 63% with an AUC of 0.828. Using supervised learning it is possible to train an algorithm to differentiate between short time intervals of pain and no pain solely based on cardiorespiratory signals. An on-site and real-time detection and rating of pain sensations would allow a precise, individuum- and treatment-tailored administration of local anesthesia. Severe phases of pain could be paused or avoided, this would allow more comfortable treatment and yield better patient compliance.

Biofunctionalization of Dental Abutment Surfaces by Crosslinked ECM Proteins Strongly Enhances Adhesion and Proliferation of Gingival Fibroblasts.

To ensure the long-term success of dental implants, a functional attachment of the soft tissue to the surface of the implant abutment is decisively important in order to prevent the penetration of bacteria into the implant-bone interface, which can trigger peri-implant disease. Here a surface modification approach is described that includes the covalent immobilization of the extracellular matrix (ECM) proteins fibronectin and laminin via a crosslinker to silanized Ti6Al4V and Y-TZP surfaces. The surface properties are evaluated using static contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The interaction of human gingival fibroblasts (HGFs) with the immobilized ECM proteins is verified by analyzing the localization of focal contacts, cell area, cell morphology, proliferation rate, and integrin expression. It is observed in the presence of fibronectin and laminin an increased cellular attachment, proliferation, and integrin expression of HGFs accompanied by a significantly higher number of focal adhesions. The presented approach holds great potential to enable a stronger bond between soft tissue and implant abutment surface. This could potentially help to prevent the penetration of bacteria in an in vivo application and thus reduce the risk of periimplant disease.

Rehabilitation of shortened dental arches: A fifteen-year randomised trial.

BACKGROUND: Few long-term studies on treatments in the shortened dental arch (SDA) are available. OBJECTIVE: The objective of this trial was to analyse the long-term success of two different treatment concepts. METHODS: Patients over 35 years of age with missing molars in one jaw and at least the canine and one premolar present on both sides were eligible. In the partial removable dental prosthesis (PRDP) group (N = 81), molars and missing second premolars were replaced by a precision attachment retained prosthesis. In the SDA group (N = 71), the dental arch ended with the second premolar that had to be present or replaced by a cantilever fixed dental prosthesis. Follow-up examinations were carried out over 15 years. RESULTS: A comprehensive outcome variable comprised four failure categories for which Kaplan-Meier survival (success) analyses were conducted. Half of the patients exhibited a continuous preservation of the per protocol prosthetic status that remained totally unaffected by complications for more than 10 years. The event-free success rates for moderate or worse failure implied a loss of the per protocol prosthetic status. The respective survival rates fell below 50% at 14.2 years in the PRDP group and 14.3 years in the SDA group. In none of the analyses, a significant group difference was found. CONCLUSIONS: In patients with an SDA condition, changes in the prosthetic status have to be expected. The affected proportion increases almost linearly from shortly after treatment and comprises the majority after 15 years. The influence of the examined treatments on success appears to be low.

5-year randomized multicenter clinical trial on single dental implants placed in the midline of the edentulous mandible.

OBJECTIVES: This multicenter randomized controlled clinical trial was conducted to investigate whether the loading protocol of single dental implants placed in the midline of edentulous mandibles will influence the implant survival or prosthetic maintenance. MATERIALS AND METHODS: In total, 158 patients were randomly assigned either to the immediate loading group (n = 81) or to the delayed loading group (n = 77). All implants were loaded with an overdenture retained by a ball attachment. RESULTS: After 5 years, 102 patients attended the follow-up investigation. Immediately loaded single implants in the midline of the edentulous mandible revealed a statistically significant lower survival rate than implants loaded conventionally over an observation period of 5 years. In the immediate loading group, 9 implants failed within the first three months of implant loading. No further implant loss was recorded for this group. Two implants failed in the delayed loading group, whereas one implant had to be removed during second-stage surgery and the second five years after implant loading. Non-inferiority of the survival rate of the midline implant of the immediate loading group, compared with the delayed loading group, could not be shown (p = .79, CI immediate loading: 74.9%; 100.0%, CI delayed loading: 73.0%; 100.0%). The observed difference in implant survival between the two treatment groups over time was statistically significant. CONCLUSIONS: The results of the present study indicate that immediate loading of a single mandibular implant in the edentulous mandible should be considered only in exceptional cases.

From a CAD/CAM-milled, allogeneic bone block to an implant-supported fixed partial denture with angulated screw channel: a case report.

Augmentation of alveolar ridge defects is a technique-sensitive procedure in dental implantology. Depending on the size of the defect, it may be necessary to use autogenous bone blocks. However, patients may be against these blocks as these procedures are surgically invasive.
Case report: This report describes the restoration of a partially edentulous mandible, which suffered a major bone defect from the right canine to the third molar site after multiple implant losses. The use of a CAD/CAM allogeneic cancellous bone block from a living donor bone was planned for the reconstruction of the alveolar ridge at the defected site. A CBCT scan was taken and the virtual planning of the bone augmentation and placement of four implants was performed. The milled bone block was fixed for augmentation and the implants were placed using a CBCT-generated surgical guide. After osseointegration, a CAD/CAM-fabricated screw-retained metal-ceramic implant fixed partial denture with angulated screw channels was delivered.
Results: The use of CAD/CAM-milled, allogeneic bone block resulted in a time-efficient and simplified reconstruction of the defect because no donor site was used, and the fit of the block on the native bone was uneventful and fast. At the 1-year follow-up, an average peri-implant vertical soft tissue decrease of 1 mm on buccal and 0.3 mm on lingual sites was observed and the peri-implant tissues were healthy.
Conclusions: The long-term success of this CAD/CAM cancellous bone block needs to be evaluated in well-designed clinical studies.