Accuracy of artificial intelligence-based segmentation of the mandibular canal in CBCT.

OBJECTIVES: To investigate the accuracy of artificial intelligence (AI)-based segmentation of the mandibular canal, compared to the conventional manual tracing, implementing implant planning software. MATERIALS AND METHODS: Localization of the mandibular canals was performed for 104 randomly selected patients. A localization was performed by three experienced clinicians in order to serve as control. Five tracings were performed: One from a clinician with a moderate experience with a manual tracing (I1), followed by the implementation of an automatic refinement (I2), one manual from a dental student (S1), and one from the experienced clinician, followed by an automatic refinement (E). Subsequently, two fully automatic AI-driven segmentations were performed (A1,A2). The accuracy between each method was measured using root mean square error calculation. RESULTS: The discrepancy among the models of the mandibular canals, between the experienced clinicians and each investigated method ranged from 0.21 to 7.65 mm with a mean of 3.5 mm RMS error. The analysis of each separate mandibular canal's section revealed that mean RMS error was higher in the posterior and anterior loop compared to the middle section. Regarding time efficiency, tracing by experienced users required more time compared to AI-driven segmentation. CONCLUSIONS: The experience of the clinician had a significant influence on the accuracy of mandibular canal's localization. An AI-driven segmentation of the mandibular canal constitutes a time-efficient and reliable procedure for pre-operative implant planning. Nevertheless, AI-based segmentation results should always be verified, as a subsequent manual refinement of the initial segmentation may be required to avoid clinical significant errors.

Material and abutment selection for CAD/CAM implant-supported fixed dental prostheses in partially edentulous patients - A narrative review.

Restorative material selection has become increasingly challenging due to the speed of new developments in the field of dental material science. The present narrative review gives an overview of the current indications for implant abutments and restoration materials for provisional and definitive implant-supported fixed dental prostheses in partially edentulous patients. For single implant restorations, titanium base abutments for crowns are suggested as an alternative to the conventional stock- and customized abutments made out of metal or zirconia. They combine the mechanical stability of a metallic connection with the esthetic potential of ceramics. For multiple-unit restorations, conical titanium bases especially designed for bridges are recommended, to compensate for deviating implant insertion axes and angulations. Even though titanium base abutments with different geometries and heights are available, certain clinical scenarios still benefit from customized titanium abutments. Indications for the definitive material in fixed implant restorations depend on the region of tooth replacement. In the posterior (not esthetically critical) zone, ceramics such as zirconia (3-5-Ymol%) and lithium-disilicate are recommended to be used in a monolithic fashion. In the anterior sector, ceramic restorations may be buccally micro-veneered for an optimal esthetic appearance. Lithium-disilicate is only recommended for single-crowns, while zirconia (3-5-Ymol%) is also recommended for multiple-unit and cantilever restorations. Attention must be given to the specific mechanical properties of different types of zirconia, as some feature reduced mechanical strengths and are therefore not indicated for all regions and restoration span lengths. Metal-ceramics remain an option, especially for cantilever restorations.

Accuracy of manual and artificial intelligence-based superimposition of cone-beam computed tomography with digital scan data, utilizing an implant planning software: A randomized clinical study.

OBJECTIVES: To investigate the accuracy of conventional and automatic artificial intelligence (AI)-based registration of cone-beam computed tomography (CBCT) with intraoral scans and to evaluate the impact of user's experience, restoration artifact, number of missing teeth, and free-ended edentulous area. MATERIALS AND METHODS: Three initial registrations were performed for each of the 150 randomly selected patients, in an implant planning software: one from an experienced user, one from an inexperienced operator, and one from a randomly selected post-graduate student of implant dentistry. Six more registrations were performed for each dataset by the experienced clinician: implementing a manual or an automatic refinement, selecting 3 small or 3 large in-diameter surface areas and using multiple small or multiple large in-diameter surface areas. Finally, an automatic AI-driven registration was performed, using the AI tools that were integrated into the utilized implant planning software. The accuracy between each type of registration was measured using linear measurements between anatomical landmarks in metrology software. RESULTS: Fully automatic-based AI registration was not significantly different from the conventional methods tested for patients without restorations. In the presence of multiple restoration artifacts, user's experience was important for an accurate registration. Registrations' accuracy was affected by the number of free-ended edentulous areas, but not by the absolute number of missing teeth (p < .0083). CONCLUSIONS: In the absence of imaging artifacts, automated AI-based registration of CBCT data and model scan data can be as accurate as conventional superimposition methods. The number and size of selected superimposition areas should be individually chosen depending on each clinical situation.

Laser induced temperature changes on the outer surface of titanium dental implants-an in vitro study.

PURPOSE: to measure the surface temperature distribution after CO2-laser heating of titanium dental implants using different power settings, application intervals and irradiation times. MATERIALS AND METHODS: 10 tissue-level-type titanium implants (Camlog Screw-line Promote Plus 4.3mm x 11mm) were embedded (Epofix, Struers ApS, Copenhagen, Denmark) and irradiated with a carbon-dioxide-laser (Denta II, Lutronic Corporation, Fremont, USA) with a wavelength of 10.6µm and at power levels of 4watts (group 1), 6watts (group 2), 8watts (group 3) and 10watts (group 4). A continuous beam mode (setting I) and non-continuous beam modes with 5second (setting II) and 10second (setting III) pause intervals were used. For each setting, a total irradiation time of 50seconds was used and repeated 10 times. The temperature was measured using external thermocouples (Testo SE & Co. KGaA, Lenzkirch, Germany) in contact with the implant surface at implant shoulder, middle and apex. A linear regression model was used to analyse the data (p = 0.05). RESULTS: Setting I demonstrated the most rapid increase in implant surface temperature in all three test sites as well as the greatest total temperature at 50 seconds of irradiation time. The greater the pause interval (settings II and III) during the 50 seconds of irradiation, the lower the rate of temperature increase as well as the total temperature in all three test sites and with all power levels. The average temperature difference between the apex and shoulder site was significant for test setting III for all groups, but not for any groups in settings I and II. CONCLUSION: Heating the internal aspect of a dental implant with a CO2-laser produces different temperature distribution profiles depending on the laser power level and the application interval. Laser-beam irradiation leads to a temperature gradient which is greatest at the implant apex and smallest at the implant shoulder.

Three-Dimensional Peri-Implant Tissue Changes in Immediately vs. Early Placed Tapered Implants Restored with Two Different Ceramic Materials-1 Year Results.

BACKGROUND: A prospective multi-center randomized controlled clinical trial was performed to digitally analyze tissue volume changes in immediately and early placed implants with simultaneous bone augmentation restored with two different all-ceramic materials. METHODS: A total of 60 patients received 60 bone-level tapered implants (BLT, Straumann AG) immediately (n = 30) or early placed, 8-10 weeks after tooth extraction, (n = 30). Implants were restored with all-ceramic single crowns fabricated out of zirconia (Lava Plus, 3M), or lithium disilicate (E.max CAD, Ivoclar Vivadent AG) bonded to titanium base abutments (Variobase for Cerec, Straumann AG). Impressions were taken at baseline (BL), 6 and 12 months, and STL data were used to define an area of interest (AOI) to analyze peri-implant volume changes and midfacial recessions. RESULTS: For immediate placement, a mean volume loss of -5.56 mm3 (±5.83 mm3) was found at 6 months, and of -6.62 mm3 (±6.56 mm3) at 12 months. For early placement, a mean volume loss of -1.99 mm3 (±5.82 mm3) at 6 months, and of -3.7 mm3 (±5.62 mm3) at 12 months was found. The differences in volume loss at 12 months between the two implant placement protocols were significant (p = 0.005). In both groups, mean midfacial recessions of 0.48 mm (±0.52) occurred. CONCLUSIONS: A more pronounced peri-implant volume loss can be expected 12 months after immediate implant placement compared with early placement.

Digital wear analysis of different CAD/CAM fabricated monolithic ceramic implant-supported single crowns using two optical scanners.

PURPOSE: To digitally evaluate the volumetric wear of four different implant-crown materials and their antagonists after artificial aging using an intraoral scanner (IOS) device and a laboratory desktop scanner. MATERIALS AND METHODS: A total of 48 implants were restored with monolithic crowns divided according to restorative material: lithium disilicate (LDS), zirconia (ZR), polymerinfiltrated ceramic network (PICN), and porcelain fused to metal (PFM). Each specimen was scanned using a desktop scanner (LAB; iScan D104, IMETRIC 3D) and an IOS (TRIOS 3, 3Shape) before and after chewing simulation (1,200,000 cycles, 49 N, steatite antagonist, 5°C to 50°C). The obtained STL files were superimposed, and the volumetric loss of substance of the crowns and their antagonists was quantified (Materialise 3-matic). Kruskal-Wallis, Spearman rho, and paired t tests were used to analyze the data (α = .05). RESULTS: The means of volume loss for each restorative material varied between 0.05 ± 0.06 mm3 (ZR with IOS) and 3.42 ± 1.65 mm3 (LDS with LAB). The wear of the antagonists was significantly lower (P < .05) for ZR than the other groups. Increased wear of the crowns was highly correlated with increased wear of their antagonists (rs = 0.859). When comparing the wear measurement using the two scanning devices, no difference in mean volume loss was found (IOS: 1.81 ± 1.81 mm3; LAB: 1.82 ± 1.78 mm3) (P = .596). CONCLUSION: Polished ZR was the most wear-resistant material and the least abrasive to the respective antagonist among the tested ceramics. For the quantification of wear, this IOS device can be used as an alternative to desktop scanners.

Communication tools and patient satisfaction: A scoping review.

OBJECTIVE: This scoping review aimed to present an overview of the literature on communication tools in esthetic dentistry. A variety of communication tools have been proposed to include patients in the shared decision-making (SDM) workflow. Only little is known about implementing communication tools in dentistry and their impact on patient communication and patient satisfaction. A systematic literature search was performed in Medline, Embase, Cochrane, and World of Science to identify if communication tools have an impact on patient satisfaction. MATERIAL AND METHODS: The search included studies from January 1, 2000 to March 3, 2020 published in English, focusing on patient communication tools and patient satisfaction in esthetic dentistry. RESULTS: Out of 6678 records, 53 full-texts were examined. Ten studies were included. Data of the included studies were extracted systematically and subsequently analyzed. All studies found that patient communication utilizing specific communication tools positively impacted either patient satisfaction, patient-dentist relationship, information retention, treatment acceptance, quality of care or treatment outcome. CONCLUSIONS: Additional communication tools besides conventional verbal communication are able to enhance patient satisfaction, improve quality of care and establish a better patient-dentist relationship. It seems essential to further develop standardized communication tools for SDM in dental medicine, which will allow the comparison of research on this topic. CLINICAL SIGNIFICANCE: This scoping review shows the importance of patient involvement in the decision-making process for improved patient satisfaction with esthetic dental treatments. With an increased implementation of communication tools, patient satisfaction and SDM may further improve in the future.

Latest advances in augmented reality technology and its integration into the digital workflow.

Smile reconstruction is achieved using rigorous and detailed methodologies that are technically demanding and both time and cost intensive. These methodologies do not include the patient during the primary conception phase. New digital technologies using augmented reality (AR) offer the option of immediate diagnosis and pre-visualization of the potential outcome before the start of treatment. A 22-year-old patient with a congenitally missing maxillary right canine, peg-shaped maxillary lateral incisors, and multiple visible diastemas required an esthetic rehabilitation. An AR virtual mock-up using specialized software was used to preview and modify the restoration proposal in real time. Using the novel 'CAD-link' workflow, the final AR proposal could be imported into CAD software and transformed into a digital wax-up with the new virtual wax copy function. After a minimally invasive preparation, the final veneer reconstructions were precisely planned according to the previously developed design proposal and bonded according to the well-known adhesive protocol. The workflow described in this article links AR with CAD/CAM technology and is expected to be time and cost efficient. This patient-centered approach involves the patient from the very beginning and is therefore an excellent communication tool between the patient and the restorative team.

CAD-CAM milled dentures: The Geneva protocols for digital dentures.

This technical report describes 2 workflows for fabricating computer-aided design and computer-aided manufacturing (CAD-CAM) milled complete dentures (CDs). The first technique illustrates a manufacturer-independent workflow using conventional clinical steps and a novel, custom modified tray to successfully fabricate CAD-CAM milled CDs. The second technique highlights a nearly digital workflow for manufacturing a CAD-CAM milled CD and a milled resin interim removable partial denture.

Explantation of an Osseointegrated Titanium Implant Using Laser-Induced Thermo-necrosis: A Case Report.

Explantation of fully or partially osseointegrated titanium implants is a complex procedure for myriad reasons and often results in major bone loss and pronounced defects of the hard and soft tissues. This may require more elaborate surgical interventions in cases of re-implantation. In this patient case, an osseointegrated titanium implant with some visible bone loss, missing attached mucosa at the buccal aspect, and a nonideal three-dimensional (3D) position had to be explanted. For this, the implant's inner connection was heated using a CO2 laser, which resulted in localized laser-induced thermo-necrosis at the bone-to-implant contact. One week following laser application, explantation could be performed easily with a torque slightly more than 35 Ncm. No complications occurred during the healing period. The result was a very easily performed explantation while preserving a maximum of the surrounding bony structure. Healing was uneventful, and no further visible bone loss could be observed during the healing time.

Retrievability of implant-supported crowns when using three different cements: a controlled clinical trial.

PURPOSE: The purpose of this study was to analyze the removal of implant-supported crowns retained by three different cements using an air-accelerated crown remover and to evaluate the patients' response to the procedure. MATERIALS AND METHODS: This controlled clinical trial was conducted with 21 patients (10 women, 11 men; mean age: 51 ± 10.2 years) who had received a total of 74 implants (all placed in the posterior zone of the mandible). Four months after implant surgery, the crowns were cemented on standard titanium abutments of different heights. Three different cements (two temporary: Harvard TEMP and Improv; and one definitive: Durelon) were used and randomly assigned to the patients. Eight months later, one blinded investigator removed all crowns. The number of activations of the instrument (CORONAflex, KaVo) required for crown removal was recorded. The patients completed a questionnaire retrospectively to determine the impact of the procedure and to gauge their subjective perception. A linear regression model and descriptive statistics were used for data analysis. RESULTS: All crowns could be retrieved without any technical complications or damage. Both abutment height (P = .019) and cement type (P = .004) had a significant effect on the number of activations, but the type of cement was more important. An increased total number of activations had no or only a weak correlation to the patients' perception of concussion, noise, pain, and unwillingness to use the device. CONCLUSIONS: Cemented implant crowns can be removed, and the application of an air-accelerated device is a practicable method. A type of cement with appropriate retention force has to be selected. The impact on the patients' subjective perception should be taken into account.