The use of an artificial intelligence-driven novel tool for the evaluation of dental implants primary stability and immediate loading feasibility: an in vitro pilot study.

PURPOSE: The primary aim of this study is to evaluate the correspondence between an Artificial Intelligence driven new tool prediction and the clinician's evaluation in the immediate loading suitability of curves recorded during implant insertion in an in vitro test. The secondary aim is to analyse peak insertion torque (pIT) and variable torque work (VTW) values of the implants used for the in vitro study. MATERIAL AND METHODS: The study was performed on artificial bone blocks of solid rigid polyurethane without cortical layer with four different densities. Five types of implants with different macrogeometries were used. A total of 140 implants (7 implants of each type in the four polyurethane blocks) were inserted. Immediately after implant placement the insertion curves were classified by the operator as suitable or non-suitable for immediate loading. In a second moment the same curves were analyzed by the new AIT that classified them as belonging to YES or NO class. For each implant pIT and VTW were also recorded. RESULTS: The correspondence between surgeon and AIT evaluation was 99,3% with only one false-negative reported by the algorithm analysis. The sensitivity resulted 98.95%, the specificity 100%, positive predictive value 100% and negative predictive value 97.8%. Mean pIT of the whole sample was 34.19 + 19.43 Ncm while mean VTW was 2266.89 + 1993.73 Ncm. Statistically significant differences were found between implant systems in the whole sample and when divided by polyurethane block density. CONCLUSIONS: AIT showed a high level of accuracy in the prediction of immediate loading suitability of insertion curves examined. All the implants used in the in vitro test were able to reach good levels of primary stability, excluding when inserted in the less dense polyurethane block. Clinical studies conducted in larger samples and with more surgeons involved are necessary to confirm these results.

Primary Stability Evaluation of a Novel Tapered Implant Inserted in Low-Density Bone Sites: An In Vitro Study.

Purpose: To evaluate primary stability of a new dental implant design in low-density bone sites, compare it with another implant design previously studied in the same bone density, and explore possible correlations between primary stability parameters. Materials and Methods: The study was carried out on fresh humid bovine bone classified as type III. The test group consisted of 30 DS Prime Taper implants (PT), and the control group consisted of 30 Astra Tech EV implants (EV). All the implants were inserted according to the protocol provided by the manufacturer. After placement, variable torque work (VTW), peak insertion torque (pIT), and resonance frequency analysis (RFA) were recorded. Results: Mann-Whitney test showed that the mean VTW and pIT were significantly higher in the test group PT compared to the control group EV; furthermore, statistical analysis showed that the mean RFA was slightly higher in the control group EV but without reaching statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in both groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values again in both groups. Conclusion: The results showed that the novel tapered implants were able to reach good primary stability in low-density bone sites and that this was superior to parallel-walled implants when measured with VTW and pIT. Moreover, a statistically significant correlation was found between the three methods used to measure implant primary stability.

The Conometric Concept: Definitive Rehabilitation of a Single Posterior Implant Using a Friction Retention Abutment. A 1-year Follow-up Report

PURPOSE: To provide a 1-year assessment of friction-retention abutments (Acuris, Dentsply Sirona) used to retain a single lithium disilicate (LS2) monolithic restoration. MATERIALS AND METHODS: A total of 522 implants were placed to treat single-tooth premolar and molar edentulous sites in the mandible or maxilla. Three types of implants were used. The tested abutments were connected 3 months after implant placement. A single pressed LS2 monolithic restoration was cemented to a dedicated titanium cap and engaged to the abutment without the use of screws or cement. Any complications affecting the restoration or the opposing dentition, soft tissue dimensional changes, the distance between the implant platform and the bone peak, and pocket probing depths were recorded at the time of restoration placement (T0), after 6 months of function (T1), and after 1 year of function (T2). Esthetic, functional, and biologic parameters were recorded at T0 and T2. RESULTS: A total of 507 patients (284 women and 223 men) received a restoration (T0), and 504 of them reached the T2 1-year follow-up. One restoration fractured after 10 months in function. No statistically significant difference was assessed in the soft tissue measurements or in the measurements of the distance between the supporting implant platform and the bone peak. None of the restorations detached during the observation period. CONCLUSION: The friction retention abutment is a viable option to retain an implant-supported monolithic LS2 glass-ceramic restoration in cases of premolar or molar single-tooth edentulism.

Histological and Biological Response to Different Types of Biomaterials: A Narrative Single Research Center Experience over Three Decades.

BACKGROUND: In more than three decades of work of the Retrieval Bank of the Laboratory for Undemineralized Hard Tissue Histology of the University of Chieti-Pescara in Italy, many types of biomaterials were received and evaluated. The present retrospective review aimed to evaluate the histological and biological aspects of the evaluated bone substitute biomaterials. METHODS: In the present study, the authors prepared a retrospective analysis after the screening of some databases (PubMed, Scopus, and EMBASE) to find papers published from the Retrieval Bank of the Laboratory for Undermineralized Hard Tissue Histology of the University of Chieti-Pescara analyzing only the papers dealing with bone substitute biomaterials and scaffolds, in the form of granules and block grafts, for bone regeneration procedures. RESULTS: Fifty-two articles were found, including in vitro, in vivo, and clinical studies of different biomaterials. These articles were evaluated and organized in tables for a better understanding. CONCLUSIONS: Over three decades of studies have made it possible to assess the quality of many bone substitute biomaterials, helping to improve the physicochemical and biological properties of the biomaterials used in daily clinical practice.

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.

Fixed Partial Restorations Made of a New Zirconia-Reinforced Lithium Silicate Material: A 2-Year Short-Term Report.

PURPOSE: To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism. MATERIALS AND METHODS: All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, grit-blasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures. RESULTS: A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade. CONCLUSION: Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research.

A 30-Year (1988-2018) Retrospective Microscopical Evaluation of Dental Implants Retrieved for Different Causes: A Narrative Review.

For decades, the histologic evidence about osseointegration and the bone-implant interface has been discussed in the literature. In this review, the effectiveness of dental implants retrieved for different causes was evaluated. A literature search was performed in databases for papers about implants retrieved from humans published by the Implant Retrieval Center of the University of Chieti-Pescara, Italy. Sixty-eight articles were selected into categories based on topics. The data indicated high level of bone-to-implant contact, lamellar bone close to the surface, roughness related to an increased bone response, organized and remodeled bone after loading, and peri-implant interfaces subjected to a continuous dynamic function.

A Narrative Review of the Histological and Histomorphometrical Evaluation of the Peri-Implant Bone in Loaded and Unloaded Dental Implants. A 30-Year Experience (1988-2018).

Background: The aim of the present review was to assess the histological and histomorphometrical data from the paper published by our Laboratory on peri-implant bone in dental implants in different loading conditions. Methods: The papers published in different implant loading conditions, in dental implants retrieved from humans, and in the Hard Tissues Research Center of the University of Chieti-Pescara, Italy, were screened on MEDLINE/PubMed, Embase, Scopus, and other electronic databases until 31 December 2018. Only articles that reported the histological and histomorphometrical values of the Bone-Implant Contact (BIC) were selected. Results: The system selection provided a total of 155 papers. The manuscripts included for the narrative review were 57. These papers provided histological and histomorphometrical data. Conclusions: The bone remodeling around dental implants was found to be a dynamic process; loading changed the microstructure of the peri-implant bone; and implants were found to provide a successful function, over several decades, with different range of degrees of BIC in vivo (varying from a little more than 30% to a little more than 90%). Loaded implants presented a 10%-12% higher BIC values when compared to submerged, unloaded implants, and rougher surfaces had, on average, about a 10% higher BIC than machined surfaces.

Guided-welded approach planning using digital scanning technology for combined screw- and conometric-retained implant-supported maxillary prosthesis.

AIM: The goal of this case series was to evaluate the clinical outcome at the 2-year follow-up of immediately loaded combined screw- and conometric-retained implant-supported full-arch restorations virtually planned using digital scanning technology. MATERIALS AND METHODS: This series included 12 patients presenting hopeless teeth in the maxilla treated with computer-guided flapless implant placement. A total of 72 implants were inserted. All implants were immediately loaded with a complete-arch restoration supported by an intraorally welded framework. Digital scanning technology was used to virtually plan a combined screw and conometric retention of the frameworks. Clinical parameters were assessed at 1 week and at 1, 3, 6, 12, and 24 months follow-up. RESULTS: The survival rate after 2 years was 98.6%, as one implant failed during the osseointegration period. No major prosthetic complications were observed such as issues with mobility, unscrewed abutments, disconnected conometric copings, and prosthetic fracture. Only one patient registered the chipping of a prosthesis. CONCLUSION: Based on the results of the present study, the use of combined screw and conometric retention for fixed immediate restorations properly planned using digital scanning technology seems to be a viable treatment alternative to screw or conometric retention alone for immediately loaded rehabilitations.

The conometric concept for the definitive rehabilitation of a single posterior implant by using a conical indexed abutment: A technique.

This report describes the restoration of the healed single implant in the posterior region by using a lithium disilicate crown supported by an Acuris abutment. The restored implants were placed in the premolar and molar region of both the mandible and the maxilla by using a 1-stage approach. The definitive Acuris abutment was placed after an implant healing period of at least 3 months. Definitive impressions were made at least 3 months after surgery. The precrystallized lithium disilicate crown was adapted to a laboratory abutment and evaluated. The crown was then crystallized, finished, colored, and cemented to the definitive abutment by using an adhesive resin cement. The definitive restoration engaged the abutment without the use of screws or cement. A single healed implant can be successfully restored by using a lithium disilicate restoration supported by an Acuris abutment.

Guided-welded approach planning using a computer-aided designed prosthetic shell for immediately loaded complete-arch rehabilitations supported by conometric abutments.

In guided surgery, implants can be planned from radiographic guide information according to a restoratively driven treatment plan. Unfortunately, the palatal or lingual surface of teeth cannot be easily identified. The present article describes the use of a digitally designed prosthetic shell to improve the accuracy of guided-welded approach planning for immediate restorations supported by conometric abutments. Importing the virtual shell into the planning software provides an effective protocol for using the definitive prosthetic space information to plan the framework shape and position predictably. This method increases the accuracy of virtual planning and reduces the time needed to reline the prosthetic shell.

The Conometric Concept: A Two-Year Follow-Up of Fixed Partial CEREC Restorations Supported By Cone-In-Cone Abutments.

PURPOSE: To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS2 FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments. MATERIALS AND METHODS: Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed  monolithic LS2 restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits. RESULTS: One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found. CONCLUSIONS: The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS2 glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.

The Conometric Concept: A 5-Year Follow-up of Fixed Partial Monolithic Zirconia Restorations Supported by Cone-in-Cone Abutments.

The use of the cone-in-cone connection to support definitive restorations was previously evaluated in cases involving full-acrylic resin or hybrid acrylic-resin composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with monolithic zirconia and supported by cone-in-cone abutments and integrated implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed in the posterior regions of partially edentulous patients after healing periods of 3 months. A total of 76 patients received fixed monolithic zirconia restorations splinted with cone-in-cone connections to two implants that were followed up yearly for 5 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services parameters modified by the World Dental Federation study design were assessed at the last follow-up appointments. The opposing dentition was categorized by type of restoration and supporting structure at the time of placement of the definitive zirconia partial restoration and at the 5-year follow-up. The treatment achieved an 88.2% success rate and a 97.4% survival rate at the 5-year follow-up. None of the prostheses became loose or detached. One fixed prosthesis (0.76%) fractured 41 months after placement. No significant difference involving peri-implant bone and probing levels between the experimental times was found. The results of this research indicated that abutment-prosthesis cone-in-cone connections were successful within the 5-year study period.

Microchemical and Micromorphologic ESEM-EDX Analysis of Bone Mineralization at the Thread Interface in Human Dental Implants Retrieved for Mechanical Complications After 2 Months to 17 Years.

The aim of this study was to analyze the degree of mineralization around nine clinically stable titanium dental implants retrieved after 2 months to 17 years for mechanical complications from five patients. The micromorphology and microchemistry of the interface bone at the coronal and apical sides of the threads were analyzed by environmental scanning electron microscope and energy-dispersive X-ray spectroscopy (EDX) on histologic samples. Mineralization was investigated by atomic calcium-to-nitrogen (Ca/N), phosphorous-to-nitrogen (P/N), and calcium-to-phosphorous (Ca/P) ratio evaluation (statistical analysis by two-way analysis of variance with Student-Newman-Keuls; P < .05). EDX showed higher Ca/N, P/N, and Ca/P values for the bone at the coronal side compared to the apical side of the threads in the long-term (≥ 14 years) samples. The two most significant findings were that (1) the interface bone located at the coronal side of the implant threads was generally more mineralized than the interface bone located at the apical side, and (2) the mineralization of the peri-implant bone at the interface increased over time. A higher degree of mineralization was found at 2 months in an immediately loaded implant when compared to the 2-month submerged unloaded control, likely related to the different remodeling events (coronal vs apical side of the implant threads) due to the direction of the loading forces.

The Conometric Concept: Definitive Fixed Lithium Disilicate Restorations Supported by Conical Abutments.

PURPOSE: The use of the conical coupling connection to support definitive restorations was evaluated in cases involving full acrylic resin or hybrid acrylic resin-composite prostheses. The aim of this study was to evaluate the performance of definitive fixed partial prostheses made with lithium disilicate and supported by coupling connection abutments and healed implants. MATERIALS AND METHODS: The prostheses were placed in the posterior regions of partially edentulous patients; 65 patients received fixed lithium disilicate restorations splinted with conical coupling connections to two implants. Implants were placed into healed sites and fresh extraction sockets. The prostheses were placed after healing periods of 3 months: restorations were followed yearly for 3 years. At each follow-up visit, peri-implant bone levels and pocket depths were recorded. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed at the last follow-up appointments. RESULTS: Two prostheses (3.07%) fractured: one was related to framework design error; one was caused by a car accident. Three patients reported small chips: these restorations were immediately polished. No significant difference involving peri-implant bone and probing levels between the experimental times were found. None of the prostheses became loose. CONCLUSIONS: The results of this research indicated that abutment-prostheses coupling connections were successful within the timeframe of this study.

Implementation of computer-guided implant planning using digital scanning technology for restorations supported by conical abutments: A dental technique.

Conometric retention has recently been proposed as an alternative to cement- or screw-retention for fixed restorations. Conometric copings can only compensate for slightly nonparallel placement without interfering with retention. This article describes a method of using digital scanning technology to facilitate computer-guided implant planning when an immediate restoration supported by conical abutments is planned with a guided-welded approach. The procedure involves importing the scan data of the conometric coping and of the definitive cast obtained from the surgical template into the implant planning software. This approach increases the accuracy of computer-guided implant planning and reduces the time needed for the surgery.

Retention Strength of Conical Welding Caps for Fixed Implant-Supported Prostheses.

PURPOSE: This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test. MATERIALS AND METHODS: Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell. RESULTS: The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry. CONCLUSION: Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

Use of Intraoral Welding to Increase the Predictability of Immediately Loaded Computer-Guided Implants.

Inaccuracy of computer-guided implant placement may lead to complications when combined with an immediately loaded prefabricated prosthesis. The aim of this case series was to describe the use of an intraoral welding technique to increase the predictability of immediately loaded implants supporting a fixed full-arch prosthesis after computer-guided flapless implant placement. A total of 60 Ankylos plus implants (Dentsply) with a width of 3.5 mm and a length of 8 to 14 mm were placed consecutively in 10 patients. The implants were functionally loaded using the intraoral welding technique on the day of surgery. The accuracy of guided implant placement was assessed by matching the planning cone beam computed tomography (CBCT) scans with postoperative CBCT scans. No mechanical or biologic complications were registered at the 1-year follow-up. The global coronal deviation of implant placement from the guide plan ranged from 0.25 to 2.84 mm (SD: 0.6 mm), with a mean of 1.28 mm. Average angle deviation was 3.42 degrees (range 0.38-7.82 degrees; SD: 1.52 degrees). The global apical deviation ranged between 0.36 and 3.85 mm (SD: 0.71 mm), with a mean of 1.65 mm. Despite the inaccuracy registered, this guided-welded approach allowed successful achievement of a passive fit of the full-arch prosthesis on the inserted implants the same day of the surgery and provided a high implant and prosthetic survival rate at the 1-year follow-up.

Fatigue limits of titanium-bar joints made with the laser and the electric resistance welding techniques: microstructural characterization and hardness properties.

Fatigue behavior of the titanium bars is of utmost importance for the safe and reliable operation of dental implants and prosthetic constructions based on these implants. To date, however, only few data are available on the fatigue strength of dental prostheses made with electric resistance welding and laser welding techniques. This in-vitro study highlighted that although the joints made with the laser welding approach are credited of a superior tensile strength, joints made with electric resistance welding exhibited double the minimum fatigue strength with respect to the joints made with laser welding (120 vs 60 N).

Influence of Stepped Osteotomy on Primary Stability of Implants Inserted in Low-Density Bone Sites: An In Vitro Study.

PURPOSE: The aims of this study were to evaluate the ability of a stepped osteotomy to improve dental implant primary stability in low-density bone sites and to investigate possible correlations between primary stability parameters. MATERIALS AND METHODS: The study was performed on fresh humid bovine bone classified as type III. The test group consisted of 30 Astra Tech EV implants inserted following the protocol provided by the manufacturer. The first control group consisted of 30 Astra Tech EV implants inserted in sites without the underpreparation of the apical portion. The second control group consisted of 30 Astra Tech TX implants inserted following the protocol provided by the manufacturer. Implant insertion was performed at the predetermined 30 rpm. The insertion torque data were recorded and exported as a curve; using a trapezoidal integration technique, the area underlying the curve was calculated: this area represents the variable torque work (VTW). Peak insertion torque (pIT) and resonance frequency analysis (RFA) were also recorded. RESULTS: A Mann-Whitney test showed that the mean VTW was significantly higher in the test group compared with the first control and second control groups; furthermore, statistical analysis showed that pIT also was significantly higher in the test group compared with the first and second control groups. Analyzing RFA values, only the difference between the test group and second control group showed statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in all groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values only in the test group. CONCLUSION: Within the limitations of an in vitro study, the results show that stepped osteotomy can be a viable method to improve implant primary stability in low-density bone sites, and that, when a traditional osteotomy method is performed, RFA presents no correlation with pIT and VTW.