Single-implant Restorations Research Articles

Evaluation of Prosthodontic Complications in Screw-Retained and Cement-Retained Crowns in Dental Implants: An Original Research

ABSTRACT Aim: Single-tooth implant restorations, whether screw-retained or cement-retained, are essential for prosthodontic rehabilitation despite having low design flexibility, cosmetic appeal, and high 5-year survival rates. Materials and Methods: A study involving 14 patients with missing mandibular first molars used 28 implants and cement-retained and screw-retained prostheses. Patients had a single edentulous gap, adequate dental hygiene, and sufficient bone volume at the implant site. The study adhered to the Helsinki Declaration, followed WHO 2007 safety guidelines, and evaluated soft tissue, bone height, and bone loss. Data analysis included the Student’s t-test and Mann–Whitney U-test. Results: In patients between the ages of 17 and 46, single-implant restorations were compared with cement- and screw-retained at 6 months. Abutment screw loosening and peri-implant soft-tissue traits did not differ significantly from one another. Conclusion: The study compared screw- and cement-retained implant restorations in 28 single-tooth implant-supported prostheses over a 6-month functional loading period, finding no significant improvement in either approach.

Digital versus Traditional Workflow for Immediate Loading in Single-Implant Restoration: A Randomized Clinical Trial.

Simple SummaryImmediate loading is nowadays a diffused technique in implantology. At the same time, digital dentistry is rapidly spreading, especially in what concerns prosthetic rehabilitation. The present study aimed to compare, through a randomized clinical trial design, the analogical vs. the traditional workflow. Single-implant restorations have been run in 50 patients, with a 12-month maximum period of follow-up after implant placement. Data were analyzed through radiological, clinical, and customer satisfaction evaluation. Importantly, and surprisingly enough, no statistically significant differences emerged between the two kinds of workflow. When assessing customer satisfaction, however, patients clearly and significantly preferred the comfort of the digital vs. traditional workflow.The purpose of this randomized controlled trial was to compare the immediate-loading protocol, in single restorations in the esthetic zone, by comparing the digital workflow in a test group (TG) vs. the analogical workflow in a control group (CG). A total of 50 patients were enrolled, requiring single hopeless tooth extraction. Twenty-five patients (TG) were randomly assigned to the immediate-loading protocol using the digital workflow, and twenty-five patients (CG) were assigned to the conventional workflow. Clinical and radiographic parameters were evaluated at the time of implant insertion (baseline) and after 3, 6 and 12 months, respectively. A clinician blind to conditions measured the Pink Esthetic Score (PES), as well as patient satisfaction. At 12-month follow-up, a cumulative survival rate of 100% was reported for all implants. No failures or biological complications were observed. No statistically significant differences were detected in the mean values of marginal bone loss and PES between the TG (0.12 ± 0.66 mm for MBL, 7.75 ± 0.89 for PES) and the CG (0.15 ± 0.54 mm for MBL, 7.50 ± 0.89 for PES). In 11 cases of TG, and 10 cases of CG, a one-year follow-up period showed an increased marginal bone level. No statistically significant differences were found in the mean total PES between test (7.75 ± 0.89) and control (7.5 ± 0.81) conditions. Furthermore, a customer satisfaction survey showed that patients preferred the digital workflow over the conventional workflow procedure (97.6 ± 4.3 vs. 69.2 ± 13.8). Digital workflow was more time-efficient than conventional workflow (97.2 ± 7.3 vs. 81.2 ± 11.3). Within the limitations of this study, no statistically significant differences were found between digital and traditional workflow.

Initial Change in the Occlusal Force and Occlusal Contact Area Following Single Molar Implant Restoration.

The occlusal force and occlusal contact area may be used to evaluate oral function following restoration of a missing tooth. This study aimed to monitor the initial changes in these factors after single molar implant restoration. Patients who underwent single implant restoration between December 2018 and September 2019 were recruited for this study. Occlusal force was measured before, immediately after, and 1 month after prosthesis placement. The occlusal contact area was evaluated immediately and 1 month after the placement. Data were grouped by sex, restored tooth, and restored side for analysis. In most groups, occlusal force was significantly increased 1 month after the placement compared with that before placement (P < .05), and the change was more significant in the first molar group than in the second molar group. There was a significant difference in the occlusal contact area of the implant prosthesis immediately and 1 month after placement when a thickness of 9 μm was used. The occlusal contact area of the natural tooth in the mesial side was significantly increased 1 month after placement (P < .05). Occlusal force was significantly increased 1 month after implant restoration, and restoration of the first molar had the most significant effect on the occlusal force. Occlusal contact areas may differ according to the occlusal indicator used in the clinical setting because the changes were significant with only 0 to 9 μm.

Microbial communities of titanium versus zirconia abutments on implant-supported restorations: Biodiversity composition and its impact on clinical parameters over a 3-year longitudinal prospective study.

Shifts in microbial communities are common over time, but they may disturb the host-microbiome homeostasis and result in inflammation of the peri-implant issues if a dysbiotic biofilm is established. Considering that different oral substrate surfaces may have a relevant impact on the microbial adhesion and colonization, the aim of this study was to investigate the microbial communities of the biofilm formed on single-implant restorations using titanium or zirconia abutments and how they correlate with clinical parameters after 3-years of implant loading. MiSeq sequencing of 16S rRNA amplicons was used to characterize the oral biofilms of individuals (n = 20) who were sampled longitudinally during 3 years of masticatory loading. Bioinformatics analysis and multivariate statistical analysis were used to evaluate the microbial diversity and clinical outcomes. Microbiomes of both abutment materials presented high alpha-diversity indices during all the experimental period, irrespective of the time of sampling. Microbial communities of titanium and zirconia were quite different over time, differing about 30% after 3 years of functional loading. Similarity of microbiomes between tested abutments and contralateral teeth was also low, ranging between 45% and 50% after 3 years of investigation. Periodontal pathogens commonly associated with peri-implantitis were found in both groups. Furthermore, both abutment materials presented strong correlations of diversity indices and microbial taxa with clinical outcomes. The type of abutment substrate significantly influenced diversity and clustering of communities during 3 years of functional loading. The time of sampling had no effect on the variables. Large correlations were found between microbial findings and clinical outcomes.

Abutment Screw Loosening in Single Implant Restorations: Evaluation of Fracture Strength of Implant-Supported Cement-Retained Monolithic Zirconia Restorations Repaired with Porcelain and Composite Resin

Aim: To assess the fracture strength of repaired implant-supported cement-retained monolithic zirconia restorations with porcelain and composite resin. Materials and methods: Nighty monolithic zirconia crowns were cemented over the implant abutments, and divided into three groups (n = 30): control, screw access hole preparation in the crown and its restoration with composite resin (HC), and screw access hole preparation in the crown and its restoration with feldspathic porcelain (HP). Fracture strength was measured by a universal testing machine. Data were analyzed (α 0.05). Conclusion: Repaired implant-supported monolithic zirconia crowns with feldspathic porcelain provided a fracture strength comparable to that in the control group.

Computer-Aided Crown Design Using Digital Scanning Technology for Immediate Postextraction Single-Implant Restorations Supported by Conical Indexed Abutments.

Conical retention with antirotational features (Acuris abutment) has been recently proposed for restorations of healed single implants. The conometric abutments use the retentive force of the coping-abutment system to retain the prosthetic crown without the use of cement or screws. This retentive force must be overcome to obtain detachment of the relined provisional crown in immediate restorations. The present article describes the use of digital scanning technology to virtually plan computer-guided implant placement and restoration with conical indexed abutments in postextraction sites. Importing the scan data of both matrix and patrix abutments that are seated on the definitive cast into the computer-aided design software provides a workflow to preoperatively mill a crown that perfectly fits the abutment into the postextraction site. This technique simplifies the provisional crown relining onto the conometric indexed abutment and reduces the intraoperative time.

Esthetic Improvement of the Maxillary Anterior Teeth during the Ten Years after Single-Implant Restoration Replacing an Ankylosed Maxillary Central Incisor in a Class II Malocclusion

This case report illustrates the long-term changes of an adult Class II malocclusion treated with premolar extraction and a single-implant restoration replacing an ankylosed upper central incisor. A 20-year-old female showing Class II malocclusion with maxillary protrusion and ankylosed upper central incisor due to previous trauma visited the clinic. To improve the occlusion, first premolars of the maxillary and mandibular arch were extracted followed by comprehensive orthodontic treatment. After orthodontic treatment, the ankylosed upper incisor was extracted and replaced with a dental implant. Overall, the occlusion was stably maintained during the 10 years of retention. Interestingly, the interdental papilla between the implant and the adjacent central incisor and the gingival soft tissue continued to remodel over time improving the micro-esthetics of the maxillary incisor region as well as the occlusion.

Integration of Intraoral Scanner-based Mandibular Movement Data for An Anterior Single-implant Restoration

Integration of Intraoral Scanner-based Mandibular Movement Data for An Anterior Single-implant Restoration

The Use of Angulated Screw Channel Abutment System for Anterior Single-Implant Restorations: A Clinical Report

The purpose of this clinical report is to explain the use and advantages of hybrid abutment crowns supported by ti-base abutments with Angulated Screw Channel (ASC) for anterior single-implant restorations. ASC system abutments have recently released to market as a solution of visible screw access problem in the esthetic zone. Moreover, using hybrid abutment consists of ti-base abutment with ASC system and esthetic materials may be a new method to combine esthetic and mechanical strength advantages for anterior single implant restorations. The use of ASC system with hybrid abutment crown design may allow clinicians to obtain optimal esthetics and mechanical strength in the case of over-angulated implants.

Relationship between Implant Length and Implant Stability of Single-Implant Restorations: A 12-Month Follow-Up Clinical Study.

Background and Objectives: Implant stability in vivo is contingent on multiple factors, such as bone structure, instrument positioning and implant surface modifications, implant diameter, and implant length. Resonance-frequency analysis is considered a non-invasive, reliable, predictable, and objective method by which to evaluate implant stability, due to its correlation with bone-to-implant contact. The purpose of this study was to evaluate the effect of implant length on the primary and secondary stability of single-implant crown rehabilitations, as measured by resonance-frequency analysis at different times. Materials and Methods: Implants of 10 and 11.5 mm were placed, and the resonance frequency was measured at the time of surgery (T0), as well as at 3 (T1), 6 (T2), and 12 (T3) months post-surgery. Results: A total of 559 implants were placed in 195 patients. Significant differences were observed when comparing the implant stability quotient (ISQ) values at T1, with values for 10-mm implants being greater than those for 11.5-mm implants (p = 0.035). These differences were also observed when comparing ISQ values for buccal and lingual areas. At T0, T2, and T3, no significant differences in ISQ values were observed. The use of 10-mm implants in the anterior maxilla yielded significantly greater values at T0 (p = 0.018) and T1 (p = 0.031) when compared with 11.5-mm implants. Significant differences in measurements were observed only for buccal areas (p = 0.005; p = 0.018). When comparing the sample lengths and sex, women with 11.5-mm implants showed significantly lower results than those with 10-mm implants (p < 0.001). Conclusions: There is a direct relationship between implants of a smaller length and greater ISQ values, with this relationship being most evident in the maxilla and in women.

Finite element analysis of narrow dental implants

Narrow-diameter implants (NDIs) traditionally have been associated to higher rates of failure in comparison with regular-diameter implants (RDIs) and wide-diameter implants (WDIs), since they generate a more unfavorable stress distribution in peri-implant bone. However, it is well known that the load sharing effect associated with prostheses supported by multiple implants (also called splinted prostheses) affords mechanical benefits. The present study involves finite element analysis (FEA) to determine whether the risks linked to NDIs could be mitigated by the mechanical advantages afforded by the splinting concept. For this purpose, a three-dimensional (3D) model of a real maxilla was reconstructed from computed tomography (CT) images, and different implants (NDIs, RDIs and WDIs) and prostheses were created using computer-aided design (CAD) tools. Biting forces were simulated on the prostheses corresponding to three different rehabilitation solutions: single-implant restoration, three-unit bridge and all-on-four treatment. Stress distribution around the implants was calculated, and overloading in bone was quantified within peri-implant volumes enclosed by cylinders with a diameter 0.1mm greater than that of each implant. The mechanical benefits of the splinting concept were confirmed: the peri-implant overloaded volume around NDIs splinted by means of the three-unit bridge was significantly reduced in comparison with the nonsplinted condition and, most importantly, proved even smaller than that around nonsplinted implants with a larger diameter (RDIs). However, splinted NDIs supporting the all-on-four prosthesis led to the highest risk of overloading found in the study, due to the increase in compressive stress generated around the tilted implant when loading the cantilevered molar.

Encode Protocol Versus Conventional Protocol for Single-Implant Restoration: A Prospective 2-Year Follow-Up Randomized Controlled Trial.

The Encode protocol for restoring single dental implants simplifies the implant impression technique by using a specially coded transmucosal healing abutment. It allows recording of the implant position without the removal of the healing abutment. This prospective randomized controlled clinical trial compares the 2-year clinical performance of the Encode and the conventional protocols for restoring single implants. A total of 47 implants were randomly allocated for restoration by the Encode (24 implants) and the conventional (23 implants) protocols. The implants were reviewed after 2 years to evaluate patient satisfaction, esthetics, prosthesis cleansability, mucosal health, bleeding on probing (BoP), metallic discoloration, probing pocket depth (PPD), marginal bone level (MBL), and quality of the proximal and occlusal contacts. In addition, all forms of complications were reported. Twenty Encode and 17 conventional implants were reviewed. The 2 protocols were comparable in all variables. A consistent increase of open proximal contacts was detected for the 2 protocols. Two Encode (10.0%) and 4 conventional (21.1%) crowns had screw loosening that was predominantly associated with cross-pins. This had led to the failure of 2 conventional crowns. Three Encode (15.0%) and 2 conventional (11.8%) crowns displayed ceramic chipping. The Encode and the conventional crowns had survival rates of 100.0% and 89.5%, respectively. From the biologic, prosthetic, and esthetic perspectives, the Encode and the conventional protocols provided a comparable clinical outcome over a 2-year duration.

Artificial intelligence in fixed implant prosthodontics: a retrospective study of 106 implant-supported monolithic zirconia crowns inserted in the posterior jaws of 90 patients

BackgroundArtificial intelligence (AI) is a branch of computer science concerned with building smart software or machines capable of performing tasks that typically require human intelligence. We present a protocol for the use of AI to fabricate implant-supported monolithic zirconia crowns (MZCs) cemented on customized hybrid abutments.MethodsThe study protocol consisted of: (1) intraoral scan of the implant position; (2) design of the individual abutment and temporary crown using computer-aided design (CAD) software; (3) milling of the zirconia abutment and the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the hybrid abutment and the temporary PMMA crown; (5) intraoral scan of the hybrid abutment; (6) CAD of the final crown with automated margin line design using AI; (7) milling, sintering and characterisation of the final MZC; and (8) clinical application of the MZC. The outcome variables were mathematical (quality of the fabrication of the individual zirconia abutment) and clinical, such as (1) quality of the marginal adaptation, (2) of interproximal contact points and (3) of occlusal contacts, (4) chromatic integration, (5) survival and (6) success of MZCs. A careful statistical analysis was performed.Results90 patients (35 males, 55 females; mean age 53.3 ± 13.7 years) restored with 106 implant-supported MZCs were included in the study. The follow-up varied from 6 months to 3 years. The quality of the fabrication of individual hybrid abutments revealed a mean deviation of 44 μm (± 6.3) between the original CAD design of the zirconia abutment, and the mesh of the zirconia abutment captured intraorally at the end of the provisionalization. At the delivery of the MZCs, the marginal adaptation, quality of interproximal and occlusal contacts, and aesthetic integration were excellent. The three-year cumulative survival and success of the MZCs were 99.0% and 91.3%, respectively.ConclusionsAI seems to represent a reliable tool for the restoration of single implants with MZCs cemented on customised hybrid abutments via a full digital workflow. Further studies are needed to confirm these positive results.

An in vitro investigation comparing methods of minimizing excess luting agent for cement-retained implant-supported fixed partial dentures

Statement of problemThe use of cement-retained implant-supported prostheses is a well-established treatment option. Techniques have been proposed to reduce the amount of residual excess cement (REC) around cement-retained single-implant restorations. However, studies evaluating the effectiveness of such techniques related to cement-retained implant-supported fixed partial dentures (CRISFPDs) are lacking. PurposeThe purpose of this in vitro study was to evaluate the effectiveness of various cement application techniques for CRISFPDs. Material and methodsTwo implant analogs were placed in the lateral incisor sites in a maxillary, 3D printed cast with 4 missing incisors. Twenty standardized, removable, printed soft-tissue replicas, 40 milled titanium custom abutments, and 20 milled zirconia CRISFPDs were fabricated. Two cement application techniques, the brush on technique (BOT), and the polyvinyl siloxane index (PI) technique were compared. Two cementation techniques, without bib (control) (n=10) and with a polytetrafluoroethylene (PTFE) bib (test) (n=10), were used. A premeasured amount of interim cement was used to cement the CRISFPDs. The CRISFPDs were retrieved after cementation, and standardized photographs of 4 quadrants of each abutment-CRISFPD assembly were made by using a software program that is used to calculate the ratio between the area covered with REC and the total specimen area. The extension of the REC on both the abutment and soft-tissue replica was measured at sites before and after cleaning the REC. A generalized linear mixed-model procedure was used for statistical analysis (α=.05). ResultsFor cement application, the polyvinyl siloxane (PVS) index technique had significantly less REC than the brush on technique (P<.05). The use of a PTFE bib led to significantly less REC than when no bib was used (P<.05). ConclusionsThe use of the PVS index technique along with a PTFE bib was effective in reducing REC for CRISFPDs.

Positional changes of the anterior maxillary teeth adjacent to single implants during 11 years + a case report

Background Single-implant treatment introduces a new biomechanical situation in the dentate patient. Various levels of infraposition of single-implant restorations have been observed in long-term follow-up studies, but little knowledge is available on the biological mechanism behind this pattern. Another post-treatment complication that has been reported increasingly during the last decade is the loss of the proximal contact point between the restored implant's crown and the adjacent natural teeth. Aim/Hypothesis To assess of tooth movements adjacent to single-implant crown in a long-term study, and to discuss these changes in relation to changes after 11 years. Material and Methods A 19-year-old healthy female, non-smoker patient was treated with one single implant in the upper central incisor after trauma. The results of the measurements of the casts and photographs were compared with clinical photographs taken at the time of treatment (2008), after 6 years (2014), and after 11 years (2019) in function. Results The clinical photographs showed obvious signs of implant infraposition after 6 years. New crowns were made in the incisor region after 6 years (2014), but signs of infraposition were again present at the final examination (2019). The small measured vertical eruption of the teeth was less than the observed clinical infraposition of the implant crowns, indicating that the vertical position of the palatal may have changed in relation to the implants as well. The vertical step measured on radiograph and photograph varied approximately 1.0 mm. Conclusion and Clinical Implications Single-implant restoration in the anterior upper jaw may present small degrees of infraposition in long-term perspectives. Obvious dentofacial changes may take place in adult patients. The clinician should carefully consider these potential changes in the treatment-planning phase, especially in young patients but also in adults of any age, with respect to the tendency of these changes to reduce with age.

Fracture Resistance of Titanium, Zirconia, and Ceramic-Reinforced Polyetheretherketone Implant Abutments Supporting CAD/CAM Monolithic Lithium Disilicate Ceramic Crowns After Aging.

The purpose of this study was to compare the fracture resistances and the fracture types of titanium, zirconia, and ceramic-reinforced polyetheretherketone (PEEK) implant abutments supporting CAD/CAM monolithic lithium disilicate ceramic crowns after in vitro dynamic loading and thermocycling aging. Three implant abutment (SKY Implant) groups-titanium (group Ti, control); zirconia with titanium base (group Zr); and ceramic-reinforced PEEK (BioHPP) with titanium base (group RPEEK); n = 12 each-were used. Thirty-six CAD/CAM monolithic lithium disilicate crowns (IPS e.max CAD) in the form of a maxillary central incisor were cemented with Panavia V5 on the abutments. The specimens were subjected to dynamic loading and thermocycling. Fracture resistances of the restorations were tested with a universal testing machine (0.5 mm/min), and their fracture patterns were analyzed. One-way ANOVA and Tukey post-hoc test were used for statistical analyses (α = .05). All samples survived after aging. The fracture strength values (mean ± standard deviation) of the groups were as follows: group Ti, 787.8 ± 120.9 N; group Zr, 623.9 ± 97.4 N; and group RPEEK, 602.9 ± 121 N. The fracture strengths were significantly higher in group Ti compared to groups Zr and RPEEK (P = .001). No significant difference was observed between groups Zr and RPEEK. Failures generally occurred due to fracture of the screw in group Ti, abutment and crown in group Zr, and crown in group RPEEK. Ceramic-reinforced PEEK abutments may be an alternative to zirconia abutments with a titanium base for single-implant restorations in the anterior region. However, there is need for further in vitro and clinical studies to evaluate the long-term performance of ceramic-reinforced PEEK abutments.

Functional implant prosthodontic score of a one-year prospective study on three different connections for single-implant restorations

Aim The aim of this prospective clinical trial was to analyze, using the Functional Implant Prosthodontic Score (FIPS), the clinical resultsof three different abutment-implant connections (1 hexagon vs 2 conical types) single-unit restorations after one year of clinical service. Material and methods Thirty patients were restored with cement-retained crowns on soft tissue level implants (10 TTc Windmix, 10 TTk Windmix and 10 Aadva GC) in posterior sites and followed-up for 1 year. FIPS was applied for objective outcome assessment beside clinical and radiographic examinations. Five variables were defined for evaluation, resulting in a maximum score of 10 per implant restoration. The patients’ level of satisfaction was recorded and correlated with FIPS. Results All implants and connected crowns revealed survival rates of 100% without any biological or technical complications after three years of loading. The total FIPS recorded for group 1 was 44, 43 in group 2 and 42 in group 3. The mean total FIPS score was 8.6±1.1, ranging from 6 to 10. The variable “bone” revealed the highest scores (2.0; range: 2–2), as well “occlusion” (2.0; range: 2–2). Mean scores for “design” (1.7 ±0.4; range: 1–2), “mucosa” (1.6±0.5; range: 1–2), and “interproximal” (1.5±0.6; range: 1–2) were more challenging to satisfy. The patients expressed a high level of functional satisfaction (80.5±2.5; range: 65–100). No type of connection showed to be superior to the other two. No statistically significant differences were found among the three tested groups. A significant correlation was found between FIPS and the subjective patients’ perception with a coefficient of 0.80 (P < 0.0001). Conclusions The findings of the clinical trial indicated the great potential of both conical and hexagon connections and their good performance after 1 year of clinical service. FIPS showed to be an objective and reliable instrument to assess implant success.

Digital versus Analog Procedures for the Prosthetic Restoration of Single Implants: A Randomized Controlled Trial with 1 Year of Follow-Up.

Aim To compare the outcome of digital versus analog procedures for the restoration of single implants. Methods Over a two-year period (2014-2016), all patients who had been treated in a dental center with a single implant were randomly assigned to receive either a monolithic zirconia crown, fabricated with digital workflow (test group), or a metal-ceramic crown, fabricated with analog workflow (control group). All patients were followed for 1 year after the delivery of the final crown. The outcomes were success, complications, peri-implant marginal bone loss (PIMBL), patient satisfaction, and time and cost of the treatment. Results 50 patients (22 males, 28 females; mean age 52.6±13.4 years) were randomly assigned to one of the groups (25 per group). Both workflows showed high success (92%) and low complication rate (8%). No significant differences were found in the mean PIMBL between test (0.39±0.29mm) and control (0.54±0.32mm) groups. Patients preferred digital impressions. Taking the impression took half the time in the test group (20±5min) than in the control (50±7min) group. When calculating active working time, workflow in the test group was more time-efficient than in the control group, for provisional (70±15min versus 340±37min) and final crowns (29±9min versus 260±26min). The digital procedure presented lower costs than the analog (€277.3 versus €392.2). Conclusions No significant clinical or radiographic differences were found between digital and analog procedures; however, the digital workflow was preferred by patients; it reduced active treatment time and costs. The present study is registered in the ISRCTN (http://www.isrctn.com/ISRCTN36259164) with number 36259164.

A Current Perspective on Screw-Retained Single-Implant Restorations: A Review of Pertinent Literature.

There is a trend toward increased use of screw-retained single-implant restorations. A comprehensive literature review was undertaken to examine the data related to screw- and cement-retention and to objectively evaluate the innovations in implant dentistry that have led to this resurgence. When comparing the two options, survival and complication rates are similar, bone and soft-tissue levels are comparable, and zirconia offers esthetic advantages for both selections. Zirconia abutments with bonded titanium inserts provide esthetic alternatives to titanium abutments for both choices. Bone- and soft-tissue responses are similar, but residual cement of cement-retained restorations is associated with significant soft- and hard-tissue complications. The potential weakness of ceramic discontinuity of screw-access openings can be lessened by the incorporation of stronger ceramic materials such as zirconia and lithium disilicate. The overriding remaining indication for cement-retained restorations is to compensate for angled implants. Screw-retained single-implant crowns should be reconsidered for many clinical situations for the following reasons: Predictable retention and retrievability No potential for the biologic consequences associated with residual cement As with cement-retained restorations, the choice between metal ceramics or all ceramics Only one margin, at the implant/abutment interface A single abutment/crown ceramic margin that can extend gingivally to the implant interface Nearly imperceptible blend of a composite resin in ceramic abutment access openings One component instead of two, which may simplify the restorative process CLINICAL SIGNIFICANCE: Innovations in implant and ceramic technology now give screw-retained prostheses the potential for esthetic, functional, and biologic outcomes that are comparable to those for cement-retained prostheses, while providing the advantages of predictable retrievability and avoidance of residual cement. Angled implants, however, remain a major indication for cement-retained single-implant prostheses. (J Esthet Restor Dent 29:161-171, 2017).

Occlusal Pressure Redistribution with Single Implant Restorations.

To describe the occlusal pressure redistribution in dental arches following placement of single posterior implant-supported restorations in occlusion with natural dentitions. Fifteen patients who presented for successfully osseointegrated single posterior implant restorations participated in the study. Cement-retained, all-ceramic implant crowns were fabricated and delivered after adjustment for interproximal contacts, fit, and uniform occlusal contacts. Occlusal pressure distribution was recorded with a digital sensor that reported contact point forces as a percentage of total pressure applied to the sensor. Measurements were taken before and after restoration for comparison. The distribution of relative occlusal stress was analyzed for statistical significance by location. The results indicated that placement of posterior implant-supported restorations increased the bite pressure in the sextants containing the restorations by an average of 4.18% (p = 0.019) of the maximum value registered (maximum bite pressure). The contralateral occlusal load was found to decrease by 2.9% (p = 0.047) of the maximum value registered; however, there was no significant difference among or between the tooth positions. Single posterior implant-supported restorations significantly increased the percentage (%) of total occlusal pressure in the containing sextant and decreased percentage of total occlusal pressure in the contralateral sextant. When analyzing restorations by exact position, more posterior implant restorations decreased the occlusal pressure applied in anterior dentitions.