Assessment of impression material accuracy in complete-arch restorations on four implants.

STATEMENT OF PROBLEM: New polyvinyl siloxane (PVS) materials with enhanced properties have been developed to improve and facilitate implant impression techniques. However, studies on their accuracy are lacking. PURPOSE: The purpose of this in vitro study was to determine the accuracy and precision of implant impressions made with some recently introduced materials on a simulated patient requiring an all-on-4 implant-supported prosthesis. Well-established polyether materials were also evaluated as a comparison. The variables considered were material type, consistency, splinting or not splinting techniques, and implant angulation. MATERIAL AND METHODS: A reference master model was made by inserting 4 implants at angles of 0, 5, and 10 degrees. Eighty impressions were made at 37 °C in wet conditions by using a standardized technique. Eight groups (n=10) were created using monophasic, single-viscosity materials (Hydrorise Implant Medium, HIM-ns; Hydrorise Implant Medium, HIM; Honigum Mono, HM; Impregum, IMP), and 2-viscosity materials (Hydrorise Implant Heavy+Light-ns, HIH+L-ns; Hydrorise Implant Heavy+Light, HIH+L; Honigum Heavy+Light, HH+L; and Permadyne and Garant [Heavy+Light, PeH+L]). Hydrorise materials were used with splinting and not splinting (ns) techniques. The reference points located on the connecting platforms of the transfer copings (TCP) were compared with the same points on the implant connecting platforms (ICP) located in the reference model. The accuracy and precision of the impressions were determined as linear 3D errors and standard deviation between each TCP-ICP couple by using an optical coordinate measuring machine (OCMM). RESULTS: PVS materials were generally better than polyether materials, with Hydrorise materials (HIM and HIH+L) showing significantly better accuracy and precision (30.9 ±14.4 µm and 28.7 ±15.5 µm, respectively) than IMP and PeH+L polyethers (44.2 ±16 µm and 43.8 ±17.6 µm, respectively; P<.001). Honigum materials were statistically similar to Hydrorise materials (P=.765). The values shown by Hydrorise nonsplinted groups (HIH+L-ns and HIM-ns) were not statistically different from those of the splinted polyether impressions (P=.386). The viscosities (monophasic or heavy+light) had no effect on accuracy, but monophasic material positively influenced precision (HIM and HIH+L, P=.001). No correlation was found between implant angulation and accuracy (multilevel analysis and Kendall rank correlation coefficient=-0.065; P=.133). CONCLUSIONS: Recently introduced materials designed for implant impressions showed significantly higher accuracy and precision; even with the unfavorable nonsplinting technique, the new materials performed similarly to, or better than, polyether materials. Although the transfer coping splinting technique generally improved the accuracy and precision of Hydrorise materials, the effect was significant only within HIH+L groups.

Fatigue resistance of monolithic lithium disilicate occlusal veneers: a pilot study.

The use of thin lithium disilicate (LD) occlusal veneers is an effective method to increase the vertical dimension of occlusion in cases of tooth wear. However, doubt remains regarding the threshold thickness to be used in this restoration class. This study aims to evaluate the effect of ceramic thickness on the survival rate and failure pattern of LD molar veneer restorations using a simplified fatigue testing machine. Sixty sound, freshly extracted human molars were used. Three groups (n = 20) were randomly created with different ceramic thicknesses (0.5, 0.8, and 1.2 mm), and 60 LD IPS e.max Press LT occlusal veneers were fabricated. The ceramic restorations were luted with a resin cement. The stainless-steel rotating drum of the ball mill contained 10 zirconia (Y-TZP) and 10 stainless steel spheres, in 500 mL of distilled water at 37 ± 1 °C. Crack growth in the LD restorations was evaluated under a stereomicroscope following each fatigue testing run (12 60-min runs). Progressive damage was observed as a function of cycling time. Survival was significantly influenced by the restoration thickness (p = 0.002, log-rank test), with thicker restorations exhibiting a higher survival rate. Thinner restorations (0.5 mm) showed significantly lower survival rate than 0.8- and 1.2-mm restorations (p < 0.016); no significant difference was observed between the 0.8- and 1.2-mm restorations. A threshold value of 0.8 mm may represent an acceptable compromise between fatigue resistance and tooth reduction.

Manufacturing of Metal Frameworks for Full-Arch Dental Restoration on Implants: A Comparison between Milling and a Novel Hybrid Technology.

PURPOSE: To determine the trueness and precision of frameworks manufactured with a selective laser melting/milling hybrid technique (SLM/m) and conventional milling by comparing the implant-platform/framework interface with those of the original computer-aided design (CAD). MATERIALS AND METHODS: Using a virtual 6-implant-supported full-arch framework CAD drawing, 27 titanium replicas were manufactured by 3 independent manufacturing centers (n = 9/center) using a hybrid SLM/m technology (labs 1 and 2) or the conventional milling technique (lab 3). Using an opto-mechanical coordinate measuring machine, the frameworks' misfit distribution and patterns were analyzed, and the position error between paired platform positions within each framework was evaluated to calculate the misfit tendency for each group. A multilevel analysis using a mixed-effects model was conducted (α = 0.05). The trueness was evaluated as the dimensional difference from the original, while the precision as the dimensional difference from a repeated scan. RESULTS: The 3 dimensional misfits differed significantly among the 3 groups, with the milled group exhibiting the least accurate outcome (p = 0.005). The mean 3D positioning errors ranged from 8 to 16 µm and from 9 to 22 µm for the SLM/m technique (labs 1 and 2, respectively), and from 20 to 35 µm for conventional milling (lab 3). Regarding the misfit distribution pattern, the misfit increased with the distance between paired platform positions in all groups. CONCLUSIONS: All groups had 3D misfits well within the error limits reported in the literature. The 3D misfits of new hybrid (SLM/milling) and conventional (milling) procedures differed significantly among them, with the milling technique the less accurate and precise. The largest errors in all groups were found between the most distant implants, resulting in a correlation between the framework span and the inaccuracies.

Translucency of IPS e.max and cubic zirconia monolithic crowns.

STATEMENT OF PROBLEM: Although several monolithic zirconia ceramics have recently been introduced, the need for improved optical properties remains. The newest cubic-zirconia has been claimed to have optimal translucency characteristics for esthetic restorations. PURPOSE: This in vitro study evaluated the optical properties of novel cubic ultratranslucent (UT) and supertranslucent (ST) zirconia by comparing them with lithium disilicate (L-DIS) glass-ceramic for the manufacture of monolithic computer-aided design and computer-aided manufacturing (CAD-CAM) molar crowns. MATERIAL AND METHODS: The UT and ST multilayered zirconia and the low-translucency grade L-DIS were milled. Eighty monolithic crowns were made from 2 CAD files, corresponding to thicknesses of 1.0 and 1.5 mm, and subdivided (n=20) into 4 groups: UT1.0, UT1.5, ST1.0, and L-DIS1.5. All groups were shaded using A2 color standard. Translucency of the crowns was measured by total transmission, using a photoradiometer in a dark chamber; furthermore, the contrast ratio was analyzed using a dental spectrophotometer applied to the buccal surface of the crowns. Data were analyzed using the Kruskal-Wallis and post hoc multiple Mann-Whitney U tests with Bonferroni correction (α=.05 divided by the number of tests performed in each set). RESULTS: When the ceramic types were analyzed, using total transmission and contrast methods, they showed significantly different translucency levels: UT1.0>ST1.0>UT1.5>L-DIS1.5 (total transmission P<.001). Contrast ratio evaluation yielded similar results (P≤.006); however, the differences between ST1.0 and UT1.5 were not significant. CONCLUSIONS: Both the ST1.0 and UT1.0 crowns, even at the maximum thickness tested (UT1.5), showed significantly higher translucency than L-DIS. Zirconia translucency was improved by eliminating the tetragonal phase, which is responsible for the toughening effect; thus, further studies are advocated to investigate the mechanical resistance of cubic zirconia.

Updates on the Construction of an Eyeglass-Supported Nasal Prosthesis Using Computer-Aided Design and Rapid Prototyping Technology.

This study was undertaken to design an updated connection system for an eyeglass-supported nasal prosthesis using rapid prototyping techniques. The substructure was developed with two main endpoints in mind: the connection to the silicone and the connection to the eyeglasses. The mold design was also updated; the mold was composed of various parts, each carefully designed to allow for easy release after silicone processing and to facilitate extraction of the prosthesis without any strain. The approach used in this study enabled perfect transfer of the reciprocal position of the prosthesis with respect to the eyeglasses, from the virtual to the clinical environment. Moreover, the reduction in thickness improved the flexibility of the prosthesis and promoted adaptation to the contours of the skin, even during functional movements. The method described here is a simplified and viable alternative to standard construction techniques for nasal prostheses and offers improved esthetic and functional results when no bone is available for implant-supported prostheses.

Work flow for the prosthetic rehabilitation of atrophic patients with a minimal-intervention CAD/CAM approach.

The implant-supported fixed rehabilitation of patients with an atrophic edentulous crest remains a challenge if bone augmentation is not planned. A minimal intervention approach for bone regeneration is necessary to minimize the flap overextension needed to close the defect over the augmented bone. Prosthetically guided bone regeneration can determine the amount of bone augmentation necessary for definitive prosthetic fixed rehabilitation. The positions of the implants and prosthetic restoration were planned; a 0.3 mm thick titanium mesh was customized for bone augmentation by using computer-aided design and computer-aided manufacturing and rapid prototyped by laser sintering, and the definitive prosthetic rehabilitation was carried out according to the initial treatment plan. This resulted in minimal bone augmentation relative to the functional needs of the definitive prosthetic rehabilitation.

Clinical outcomes and success rates of quartz fiber post restorations: A retrospective study.

STATEMENT OF PROBLEM: Cast metal posts and dowels are inherently dark and, when metal-free restorations are used, could impair the definitive esthetic appearance. Quartz fiber posts could represent a reliable choice for restoring abutment teeth. PURPOSE: The purpose of this study was to evaluate the long-term success rate of teeth restored with quartz fiber posts and fixed dental prostheses (FDPs). MATERIAL AND METHODS: Ninety-nine teeth restored with 114 quartz fiber posts and FDPs were evaluated. The evaluation time ranged from 7 months to 9.25 years. The Kaplan-Meier method was used to obtain success curves. The influence of the tooth location, definitive restoration, and failure pattern upon the success function was analyzed with the log-rank test. The Cox regression test was used to evaluate possible predictors among the interactions of the observed parameters. RESULTS: The success rate of the restorations was 85.86% in a mean period of 5.88 ±1.37 years, with an estimated success probability of 85% at 6.17 years. The statistical analysis identified the factors related to the arch (P=.045) and type of definitive restoration (P=.021) as significantly associated with success. Post debonding was the most frequent failure mode, followed by endodontic failure, with the latter not necessarily being related to the post itself. No root fractures were recorded. Twelve teeth out of the 14 that failed were restored again, bringing the overall survival rate of the teeth to 98%. CONCLUSIONS: The rehabilitation of abutment teeth with quartz fiber posts can be considered a reliable procedure; however, adhesive techniques and luting materials require improvement.

Mutational landscape of HSP family on human breast cancer.

Breast cancer (BRCA) is a prevalent malignancy with the highest incidence among females. BRCA can be categorized into five intrinsic molecular subtypes (LumA, LumB, HER2, Basal, and Normal), each characterized by varying molecular and clinical features determined by the expression of intrinsic genes (PAM50). The Heat Shock Protein (HSP) family is composed of 95 genes evolutionary conservated, they have critical roles in proteostasis in both normal and cancerous processes. Many studies have linked HSP to the development and spread of cancer. They modulate the activity of multiple proteins expressed by oncogenes and anti-oncogenes through a range of interactions. In this study, we evaluate the mutational changes that HSP undergoes in BRCA mainly from the TCGA database. We observe that Copy Number Variations (CNV) are the more frequent events analyzed surpassing the occurrence of point mutations, indels, and translation start site mutations. The Basal subtype showcased the highest count of amplified CNV, including subtype-specific changes, whereas the Luminals tumors accumulated the greatest number of deletion CNV. Meanwhile, the HER2 subtype exhibited a comparatively lower frequency of CNV alterations when compared to the other subtypes. This study integrates CNV and expression data, finding associations between these two variables and the influence of CNV on the deregulation of HSP expression. To enhance the role of HSP as a risk predictor in BRCA, we succeeded in identifying CNV profiles as a prognostic marker. We included Artificial Intelligence to improve the clustering of patients, and we achieved a molecular CNV signature as a significant risk factor independent of known classic markers, including molecular subtypes PAM50. This research enhances the comprehension of HSP DNA alterations in BRCA and its relation with predicting the risk of affected individuals providing insights to develop guide personalized treatment strategies.

Evaluation of trueness and precision of removable partial denture metal frameworks manufactured with digital technology and different materials.

PURPOSE: The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. MATERIALS AND METHODS: 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. RESULTS: The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson's Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. CONCLUSION: All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

Analysis of the trueness and precision of complete denture bases manufactured using digital and analog technologies.

PURPOSE: Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS: Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS: There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION: The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

New Working Capabilities for Coping With COVID Time Challenges.

The COVID-19 pandemic played as a booster to the cultural, social, and economic transformations triggered by the 4.0 Industrial Revolution, increasing the diffusion and employment of technological devices and requiring to reconsider the traditional approach to work and organization. Dealing with an emblematic organizational case, the article highlights the main key capabilities requested to face the current scenario, suggesting transformed attitudes needed to cope with the unfolding complex, uncertain, changing digital and blended world. The findings, gathered through an extensive survey involving 500 people who started working at a distance during the 2020 lockdown period, underline the main actionable skills to be achieved for enhancing agile work, hybrid professional roles and new work, and organizational and managerial cultures.

Computer-aided design and manufacturing construction of a surgical template for craniofacial implant positioning to support a definitive nasal prosthesis.

AIM: To design a surgical template to guide the insertion of craniofacial implants for nasal prosthesis retention. MATERIALS AND METHODS: The planning of the implant position was obtained using software for virtual surgery; the positions were transferred to a free-form computer-aided design modeling software and used to design the surgical guides. A rapid prototyping system was used to 3D-print a three-part template: a helmet to support the others, a starting guide to mark the skin before flap elevation, and a surgical guide for bone drilling. An accuracy evaluation between the planned and the placed final position of each implant was carried out by measuring the inclination of the axis of the implant (angular deviation) and the position of the apex of the implant (deviation at apex). RESULTS: The implant in the glabella differed in angulation by 7.78°, while the two implants in the premaxilla differed by 1.86 and 4.55°, respectively. The deviation values at the apex of the implants with respect to the planned position were 1.17 mm for the implant in the glabella and 2.81 and 3.39 mm, respectively, for those implanted in the maxilla. CONCLUSIONS: The protocol presented in this article may represent a viable way to position craniofacial implants for supporting nasal prostheses.

Mandibular reconstruction using a new design for a patient-specific plate to support a fibular free flap and avoid double-barrel technique.

Mandibular reconstruction is a primary concern for head and neck reconstructive surgeons because of the aesthetic restoration needs after ablative surgery, as well as for functional reasons: the mandible has a central functional role in speaking, swallowing and mastication. It is generally agreed that the gold standard for mandibular reconstruction is a bone free flap supported by a reconstructive titanium plate. The fibular flap represents the first choice for multi-segment mandibular reconstruction. The fibula, harvested as a single barrel graft, does not exhibit sufficient thickness to reach the original height of the native mandible; therefore, the positioning of dental implants is often deeper than that of the native alveolar crest. The aim of this study was to evaluate the positioning of the fibular free flap as it pertains to the restoration of vertical mandible height, by modifying the design of a 3D-printed titanium patient-specific implant (PSI). In this novel reconstructive workflow, the customised plate was projected to support the fibular flap at an alveolar bone position above the typical inferior mandibular border, and carried out on four patients. All patients were treated for benign neoplasms involving mandibular bone. Clinical outcomes and accuracy of the procedure are described. Our reconstructive proposal appears to be a valid alternative to the double-barrel technique in order to restore the vertical height of the reconstructed mandible.^ieng

La ricostruzione mandibolare è particolarmente rilevante per il chirurgo cervico-cefalico, in quanto influenza significativamente i successi in termini di risultati estetici e funzionali per il paziente. Il gold standard per tale ricostruzione è l'utilizzo di lembi ossei rivascolarizzati, stabilizzati mediante una placca ricostruttiva in titanio. Il lembo di fibula rappresenta la prima scelta ricostruttiva laddove necessitino molteplici segmenti ossei. Tuttavia questo lembo, allestito secondo la tecnica della singola barra, non permette di ripristinare l'altezza mandibolare nativa, adeguata per una corretta riabilitazione masticatoria implanto-supportata. Lo scopo di questo studio è quindi presentare un nuovo design di placca ricostruttiva custom-made, atta a posizionare il segmento osseo di fibula in una posizione più coronale, evitando pertanto la necessità di allestire il lembo secondo la tecnica della doppia barra. La placca custom-made contribuisce inoltre al mantenimento del profilo mandibolare, garantendo il ripristino morfologico della ricostruzione. Questo protocollo è stato eseguito su quattro pazienti sottoposti a resezione mandibolare per tumori benigni. I risultati clinici e di accuratezza della procedura sono presentati. Il protocollo presentato sembra una valida alternativa alla tecnica della doppia barra al fine di ripristinare l'altezza mandibolare nativa.

Fatigue failure and success rate of lithium disilicate table-tops as a function of cement thickness.

Purpose Under thin, partial coverage restoration the proper cement thickness to be clinically employed still remains an issue. The aim of this study was to determine the failure and success rates of simplified lithium disilicate occlusal veneers as a function of cement thickness. The null hypothesis was that cement thickness has no effect on the fatigue resistance.Methods Sound human molars were severed in a plane parallel to the occlusal surface to create a flat dentin surface surrounded by enamel edges. Forty-five occlusal veneers 1.0 mm thick (IPS e.max CAD LT) were luted to the teeth with Multilink Automix resin cement, creating 3 experimental groups (n=15) with cement thicknesses of 50, 100, and 200 µm. The restorations were fatigue-cycled using a ball mill machine containing zirconia and stainless steel spheres. Twelve 60 min cycles were performed. Survival statistics were applied to "failure" and "success" events, comparing the three groups using a log-rank Mantel-Cox test and a log-rank test for trends (alpha = 0.05).Results The failure and success rates were not significantly influenced by cement thickness (P = 0.137 and P = 0.872, respectively); thus, the null hypothesis was accepted. However, when log-rank test for trends was applied to failure events, the tendency to have less failures with increasing thicknesses was found statistically significant (P = 0.047).Conclusions The cement thickness within the range adopted here did not have a significant effect on the failure or success rate of lithium disilicate occlusal veneers when exposed to randomized impact stresses generating fatigue phenomena.

Immediate facial rehabilitation in cancer patients using CAD-CAM and rapid prototyping technology: a pilot study.

PURPOSE: This study describes the workflow in a procedure to create a provisional facial prosthesis for cancer patients using digital and rapid prototyping technologies without the need for supporting craniofacial implants. MATERIALS AND METHODS: An integrated workflow procedure aimed at the construction of provisional silicone prosthesis was used to rehabilitate a facial disfigurement in a patient who had undergone ablative surgery of the midface. A laser scan of the defect was obtained, and a digital model of the patient's face was constructed using virtual mirroring of the healthy side and referencing the "Nose Digital Library." RESULTS: The missing volume of the face was reconstructed, and a rapid-prototyped mold was devised to process the silicone prosthesis. A provisional eyeglasses-supported prosthesis designed with a CAD/CAM-projected titanium substructure was connected using the micro-components of implant prosthetic devices. CONCLUSIONS: The workflow described herein offers a viable procedure for quickly restoring facial defects by means of provisional prosthetic rehabilitation.

Rehabilitation of the nose using CAD/CAM and rapid prototyping technology after ablative surgery of squamous cell carcinoma: a pilot clinical report.

Restoration of a nasal defect after ablative surgery for squamous cell carcinoma necessitates replacing the missing volume and anchoring a prosthesis to the patient's face. This report describes the failure of plastic reconstructive surgery after ablation of a squamous cell cancer of the nose and the esthetic and functional restoration of the patient with a nasal prosthesis. The process of making an implant-supported prosthesis using digital technology, including digitized anatomic models from a "nose library," and the rapid prototyping of the mesiostructure for bar anchorage and of the mold for silicone processing are presented.

Translucency of zirconia copings made with different CAD/CAM systems.

STATEMENT OF PROBLEM: Zirconia cores are reported to be less translucent than glass, lithium disilicate, or alumina cores. This could affect the esthetic appearance and the clinical choices made when using zirconia-based restorations. PURPOSE: The purpose of this in vitro study was to evaluate the translucency of zirconia copings for single crowns fabricated using different CAD/CAM systems, using lithium disilicate glass ceramic as a control. MATERIAL AND METHODS: Using impressions made from a stainless steel complete-crown master die, 9 stone cast replicas were fabricated, numbered, and distributed into 8 ceramic ZrO(2) CAD/CAM system groups (Lava Frame 0.3 and 0.5, IPS e.max ZirCAD, VITA YZ, Procera AllZircon, Digizon, DC Zircon, and Cercon Base) and to a lithium disilicate glass-ceramic control group (IPS e.max Press) using a simple computer-generated randomization method. From each die, the manufacturer's authorized milling centers supplied 5 copings per group without applying any dying technique to the ceramic base material. The copings were prepared to allow for a 40-mum cement layer and were of different thicknesses according to system specifications. Translucency was measured by the direct transmission method with a digital photoradiometer mounted in a dark chamber. The light source was a 150-W halogen lamp beam. Measurements were repeated 3 times for each specimen. Data obtained were analyzed using 1-way ANOVA and the Bonferroni multiple comparison test (alpha=.05). RESULTS: Among ZrO(2) copings, Lava (0.3 mm and 0.5 mm thick) showed the highest (P<.05) values of translucency measured as light flow units (3.572 + or - 018 x 10(3) lx and 3.181 + or - 0.13 x 10(3) lx, respectively). These values represent 71.7% and 63.9%, respectively, of the glass-ceramic control group (4.98 x 10(3) lx). CONCLUSIONS: All ZrO(2) copings demonstrated different levels of light transmission, with the 2 Lava specimens showing the highest values. Translucency of zirconia copings was significantly lower (P=.001) than that of the lithium disilicate glass-ceramic control.

The prototype concept in a full digital implant workflow.

BACKGROUND: The aim of this case report is to describe the innovative concept of a prototype use in a digital implant workflow. A prototype is required for simultaneous evaluation of the accuracy of a dental impression and esthetic and functional parameters before final framework realization. CASE DESCRIPTION: Three digital impressions were obtained to create a master file, which contained information on the 3-dimensional (3D) position of the implant, the gingival architecture, and the esthetic and functional features of the provisional restoration. A stereolithographic master model (SMM) featuring implant analogs was 3D printed. Two prototypes were realized with the use of 2 different modalities. The first resin prototype (A), which lacked implant connections, was produced with the use of a certified digital workflow process. The titanium connections were luted onto the SMM. The second resin prototype (B), considered experimental, was a single piece with milled implant connections. Both prototypes were tested in the patient by means of visual inspection, finger pressure testing, screw resistance testing, and periapical radiography. In the case of accurate fit of prototype A or B on the SMM and misfit in the patient, the impression should be invalidated. For prototype B, in the case of proper fit in the patient and misfit on the SMM (because of the occurrence of an error during 3D printing, incorrect analog position, or both), the impression should be validated, but the model should be adapted. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The use of a prototype allows the clinician to simultaneously test implant position and esthetic and functional parameters. However, a single-structure prototype could be preferable for the identification of impression inaccuracy.

Prosthetically CAD-CAM-Guided Bone Augmentation of Atrophic Jaws Using Customized Titanium Mesh: Preliminary Results of an Open Prospective Study.

This study evaluated the outcomes of computer-aided design-computer-aided machining (CAD-CAM)-customized titanium mesh used for prosthetically guided bone augmentation related to the occlusion-driven implant position, to the vertical bone volume gain of the mandible and maxilla, and to complications, such as mesh exposure. Nine patients scheduled for bone augmentation of atrophic sites were treated with custom titanium mesh and particulate bone grafts with autologous bone and anorganic bovine bone in a 1:1 ratio prior to implant surgery. The bone volume needed to augment was virtually projected based on implant position, width, and length, and the mesh design was programmed for the necessary retaining screws. After 6 to 8 months, bone augmentations of 1.72 to 4.1 mm (mean: 3.83 mm) for the mandibular arch and 2.14 to 6.88 mm (mean: 3.95 mm) for the maxilla were registered on cone-beam computerized tomography. Mesh premature (within 4 to 6 weeks) exposure was observed in 3 cases and delayed (after 4 to 6 weeks) in 3 other cases. One titanium mesh was removed before the programmed time but in all augmented sites was possible implant insertion. No complication occurred during prosthetic follow-up. Using CAD-CAM technology for prosthetically guided bone augmentation showed important postoperative morbidity of mesh exposure (66%). Because of this high prevalence of mesh exposure and the potential infection that could affect the expected bone augmentation, this study suggests a cautious approach to this procedure when designing the titanium mesh, to avoid flap tension that may cause mucosal rupture.