Virtual implant scan body switch by using computer-aided design programs avoiding the need of obtaining a new intraoral implant digital scan: A novel protocol.

OBJECTIVE: The present manuscript describes a technique to virtually switch an implant scan body eliminating the need of obtaining a new intraoral implant digital scan. CLINICAL CONSIDERATIONS: Implant scan bodies assist on transferring the 3-dimensional position of the implants into the virtual definitive implant cast. However, if a different implant part is desired during the designing procedures of the implant restoration such as selecting a different implant abutment of varying height, angulation, or manufacturer, a new intraoral implant digital scan with the specific implant scan body is required. CONCLUSIONS: This novel protocol aims to reduce possible complications that require capturing a new intraoral implant digital scan, facilitate prostheses design modifications after the obtention of the definitive intraoral implant digital scan, and to ease the manufacturing procedures. CLINICAL SIGNIFICANCE: The novel technique may provide a solution for virtually switch implant scan bodies for fabricating implant-supported single crowns or short-span prostheses. Additional studies are needed before its clinical implementation.

Accuracy of maximum intercuspal position located by using four intraoral scanners and an artificial intelligence-based program.

STATEMENT OF PROBLEM: Maxillary and mandibular scans can be articulated in maximum intercuspal position (MIP) by using an artificial intelligence (AI) based program; however, the accuracy of the AI-based program locating the MIP relationship is unknown. PURPOSE: The purpose of the present clinical study was to assess the accuracy of the MIP relationship located by using 4 intraoral scanners (IOSs) and an AI-based program. MATERIAL AND METHODS: Conventional casts of a participant mounted on an articulator in MIP were digitized (T710). Four groups were created based on the IOS used to record a maxillary and mandibular scan of the participant: TRIOS4, iTero, i700, and PrimeScan. Each pair of nonarticulated scans were duplicated 20 times. Three subgroups were created: IOS, AI-articulated, and AI-IOS-corrected subgroups (n=10). In the IOS-subgroup, 10 duplicated scans were articulated in MIP by using a bilateral occlusal record. In the AI-articulated subgroup, the remaining 10 duplicated scans were articulated in MIP by using an AI-based program (BiteFinder). In the AI-IOS-corrected subgroup, the same AI-based program was used to correct the occlusal collisions of the articulated specimens obtained in the IOS-subgroup. A reverse engineering program (Geomagic Wrap) was used to calculate 36 interlandmark measurements on the digitized articulated casts (control) and each articulated specimen. Two-way ANOVA and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were used to analyze precision (α=.05). RESULTS: Significant trueness discrepancies among the groups (P<.001) and subgroups (P<.001) were found, with a significant interaction group×subgroup (P<.001). The Levene test showed significant precision discrepancies among the groups (P<.001) and subgroups (P=.005). The TRIOS4 and iTero groups obtained better trueness and lower precision than the i700 and PrimeScan systems. Additionally, the AI-articulated subgroup showed worse trueness and precision than the IOS and AI-IOS-corrected subgroups. The AI-based program improved the MIP trueness of the scans articulated by using the iTero and PrimeScan systems but reduced the MIP trueness of the articulated scans obtained by using the TRIOS4 and i700. CONCLUSIONS: The trueness and precision of the maxillomandibular relationship was impacted by the IOS system and program used to locate the MIP.

An additively manufactured, magnetically retained, and stackable implant surgical guide: A dental technique.

The digital workflow for designing and fabricating a magnetically retained and stackable additively manufactured implant surgical guide is described. The technique should improve the stability of the stackable surgical guide and the accuracy of implant placement.

Implant-supported overdenture with horizontal insertion for treating the edentulous atrophic maxilla: A case series.

STATEMENT OF PROBLEM: Rehabilitation of edentulous patients with severe maxillary atrophy is a clinical challenge. Although several treatment options are available, the implant-supported overdenture has been widely advocated. However vertical insertion implant-supported overdentures have drawbacks, including wear, aging, and the continuous maintenance of retention systems. Whether an implant-supported overdenture with a horizontal insertion pathway can overcome these problems is unclear. PURPOSE: The purpose of this observational study was to determine the clinical and biological behavior of a new type of implant-supported overdenture with a horizontal insertion pathway over a mean clinical follow-up period of 6 years. MATERIAL AND METHODS: Ten study participants with an atrophic maxilla underwent rehabilitation with horizontal overdentures supported by 6 implants. Follow-up visits were scheduled at 3 months, 6 months, and annually thereafter. The variables analyzed were implant and prosthetic survival, peri-implant tissue behavior, mechanical complications, and patient satisfaction. RESULTS: The follow-up period ranged from 5 to 8 years, mean ±standard deviation 6.3 ±1.2 years. A total of 60 implants and 10 horizontal overdentures were placed. The clinical survival of the implants was 98.3% (mean peri-implant bone loss, 1.3 ±0.4 mm) and was 80% of the prostheses. Overall, mean patient satisfaction as assessed with a visual analog scale was 7.4, with 8.5 for esthetics and 9.5 for function. CONCLUSIONS: The horizontal implant-supported overdenture provided a functional alternative to conventional prostheses.

Work environment, job satisfaction and burnout among Spanish dentists: a cross-sectional study.

BACKGROUND: The main aim of the present study was to examine the relationships among work environment, job satisfaction and burnout in dentists and to analyse the way in which certain sociodemographic variables, such as gender, professional experience and weekly working hours, predict the perception of the work environment. METHODS: A battery of online questionnaires was sent to 3876 dentists officially registered in the triple-province region of Valencia; the battery included the Survey of Organizational Attributes for Dental Care, the Warr-Cook-Wall Overall Job Satisfaction Scale, the Maslach Burnout Inventory and a series of sociodemographic questions formulated for the specific purpose of this study. To assess the relations with the independent variables, we calculated the Pearson correlation coefficient, the Z-scores were calculated to make effect sizes comparable, and the associations between the scales and the sociodemographic variables were investigated by adjusted multiple regression analysis. RESULTS: A total of 336 participants (9.4%) correctly completed the survey in this study. The mean (M) age was 37.6 years old (standard deviation (SD) = 9.6, median (Me) = 34). Participants reported high scores on the work environment and job satisfaction scales, with only limited experiences of burnout (3.8%). Work environment and burnout were significantly and positively predicted by years of professional experience (ß = .078; p = .000 and ß = .107; p = .004, respectively), and job satisfaction was significantly and positively predicted by weekly hours of work (ß = .022; p = .001), without significant differences according to gender. CONCLUSIONS: Dentists who work over 20 hours a week and have more years of professional experience report having better perceptions of well-being at work, with no significant difference according to gender. It is important to highlight the aspects that improve well-being in dentistry to reduce burnout, which would lead to greater work engagement and better attention to patients.

Implant-supported metal-ceramic and resin-modified ceramic crowns: A 5-year prospective clinical study.

STATEMENT OF PROBLEM: Because of market demand for innovation, new restoration materials have been introduced without adequate testing; clinical failure may be the consequence, and clinical studies are needed. PURPOSE: The purpose of this clinical study was to evaluate the biological and mechanical clinical behavior of implant-supported resin-modified ceramic crowns compared with that of metal-ceramic crowns. MATERIAL AND METHODS: Forty-two participants aged between 35 and 65 years received single implants in posterior edentulous sites. After the osseointegration period, half of the implants (selected randomly) (n=25) were restored with metal-ceramic crowns (MC group) and the other half with resin-modified ceramic crowns (RMC group) bonded with dual-polymerized resin cement onto titanium abutments. The biomechanical state of the restorations and implants was analyzed. RESULTS: Mean peri-implant bone loss after 5 years of functional life was 0.3 ±0.6 mm. The implant clinical survival rate was 98%. RMC crowns had a survival rate of 70%, whereas MC crowns had a 100% survival rate. RMC crowns had more mechanical complications than the MC group (P<.001). Peri-implant bone loss showed no significant differences between crown type (P=.175). CONCLUSIONS: All peri-implant bone loss values were within the range considered acceptable. Metal-ceramic crowns showed better mechanical behavior than resin-modified ceramic crowns. Biological responses of peri-implant tissue would appear to be independent of the type of cemented crown.

Maxillary Implant-Supported Overdentures: Mechanical Behavior Comparing Individual Axial and Bar Retention Systems. A Cohort Study of Edentulous Patients.

Background and objectives: To compare the medium- to long-term mechanical behavior of overdentures with two different retention systems: overdentures with Locator® axial retention, and vertical insertion overdentures with bar retention, used to rehabilitate edentulous maxillar. Material and Methods: This prospective study assessed patients presenting complete maxillary edentulism, rehabilitated by means of implant-supported overdentures (n = 20), 10 with Locator® axial retention (ODA group) and 10 with overdentures on bars (ODB group). Patients also completed a questionnaire to determine their satisfaction with treatment. Results: The mean follow-up time in both groups was 11.4 years, with follow-up times in both groups ranging from 5 to 14 years. The ODA group suffered mechanical complications such as retention loss, need for nylon retention insert changes, resin fracture, and need for relining. In the ODB group, prosthetic dental wear, screw loosening, and complete prosthetic failure were more common. A total of 19 implants failed (23.8%); of these, 11 were in the ODA group (failure rate = 27.5%) and eight in the ODB group (failure rate = 20%). The patient satisfaction questionnaire obtained a mean score of 7.9 out of 10 in the ODA group, and 9.75 in the ODB group. Conclusions: in rehabilitations of edentulous maxillar by means of implant-supported overdentures, both the systems assessed were shown to be effective in the medium to long term. Patients expressed a high level of satisfaction with the treatments received.

Fracture Resistance of New Metal-Free Materials Used for CAD-CAM Fabrication of Partial Posterior Restorations.

Background and Objectives: To evaluate in vitro the fracture resistance and fracture type of computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Discs were fabricated (10 × 1.5 mm) from four test groups (N = 80; N = 20 per group): lithium disilicate (LDS) group (control group): IPS e.max CAD®; zirconium-reinforced lithium silicate (ZRLS) group: VITA SUPRINITY®; polymer-infiltrated ceramic networks (PICN) group: VITA ENAMIC®; resin nanoceramics (RNC) group: LAVA™ ULTIMATE. Each disc was cemented (following the manufacturers' instructions) onto previously prepared molar dentin. Samples underwent until fracture using a Shimadzu® test machine. The stress suffered by each material was calculated with the Hertzian model, and its behavior was analyzed using the Weibull modulus. Data were analyzed with ANOVA parametric statistical tests. Results: The LDS group obtained higher fracture resistance (4588.6 MPa), followed by the ZRLS group (4476.3 MPa) and PICN group (4014.2 MPa) without statistically significant differences (p < 0.05). Hybrid materials presented lower strength than ceramic materials, the RNC group obtaining the lowest values (3110 MPa) with significant difference (p < 0.001). Groups PICN and RNC showed greater occlusal wear on the restoration surface prior to star-shaped fracture on the surface, while other materials presented radial fracture patterns. Conclusion: The strength of CAD-CAM materials depended on their composition, lithium disilicate being stronger than hybrid materials.

Influence on peri-implant bone loss of different fixed partial dentures retained on 2 implants.

STATEMENT OF PROBLEM: Marginal bone loss is key to determining the success of dental implants. However, how different factors, including the extension or span of implant-supported restorations and implant position, affect bone loss is unclear. PURPOSE: The purpose of this prospective clinical study was to analyze peri-implant bone loss 3 years after loading by evaluating the influence of implant position and prosthetic type and comparing splinted crowns and 3- or 4-unit fixed partial dentures (FPDs) to determine whether 2 dental implants can achieve comparable success when replacing 2, 3, or 4 missing teeth. MATERIAL AND METHODS: Sixty-two adjacent dental implants in 23 participants were investigated. The implants supported noncantilevered restorations: 2 splinted crowns or 3- or 4-unit FPDs. Bone loss was evaluated 3 years after loading from periapical radiographs using AutoCAD software. Nonparametric comparisons were made. The Wilcoxon test was applied to determine homogeneity of related samples. The Mann-Whitney test was applied to measure homogeneity of bone loss in 2 independent samples and the presence/absence of a pontic in the restoration (α=.05). RESULTS: Mean ±standard deviation peri-implant bone loss was 0.9 ±0.7 mm. The peri-implant bone loss of the restorations analyzed was similar to the average values of 1.1 ±0.8 mm for 3- and 4-unit FPDs and 0.8 ±0.6 mm for splinted crowns. The type of prosthodontic restoration and implant position did not show significant influences on bone loss (P>.05). CONCLUSIONS: Mean bone loss values were within an acceptable range. Statistically significant relationships were not found between the restoration types, suggesting that 3 or 4 missing teeth can be replaced by 2 implants. Further studies with longer follow-ups are needed to obtain clinically applicable conclusions.

Patient-centered and clinical outcomes of mandibular overdentures retained with the locator system: A prospective observational study.

STATEMENT OF PROBLEM: Whether clinical or demographic variables affect the perception of treatment in terms of quality of life and satisfaction is unknown. PURPOSE: The purpose of this prospective study was to make an evidence-based assessment of the treatment outcomes (patient- and clinically based) of locator-retained mandibular overdentures. MATERIAL AND METHODS: This prospective observational study assessed patients with edentulism who had worn mandibular overdentures supported by 2 implants and retained by the locator system for at least 1 year of functional life (N=80). Medical histories were reviewed, and patients underwent oral examinations. Prosthetic clinical outcomes and patient well-being were registered using the Oral Health Impact Profile 20 (OHIP-20) and Oral Satisfaction Scale (OSS). RESULTS: Patient well-being scored an overall OHIP-20 score of 19.0 ±14.0 of 80 (the higher the score, the greater the impact and the worse the oral health-related quality of life); overall oral satisfaction was 8.3 ±1.7 of 10. Women suffered greater social impact (0.8 ±1.0) and disability (0.4 ±0.8) than men (0.4 ±0.7 versus 0.2 ±0.4, respectively). Impact on well-being was inversely proportional to both patient age and the age of the prosthesis (r=-0.25; P<.01). Implants had been placed on average 73.6 ±39.2 months previously, showing a survival rate of 82.5%. Most of the overdentures had been functioning for over 60 months. Relining (46.3%), readjustments (82.5%), and changes of nylon retention (1.5 ±1.8 per patient over 60 months of use) devices negatively influenced well-being. CONCLUSIONS: Mandibular overdentures produced good results with regard to quality of life and oral satisfaction, but attention should be paid to factors affecting clinical outcomes and patient well-being.

Oral health-related quality of life of implant-supported overdentures versus conventional complete prostheses: Retrospective study of a cohort of edentulous patients.

BACKGROUND: This work aims to confirm if implant-supported overdentures are a good treatment option for edentulous patients and offer an improvement in quality of life compared with traditional complete prostheses (dentures). MATERIAL AND METHODS: This retrospective clinical descriptive study included three evaluation groups: validation group (n=57); control group of patients with complete removeable prostheses (n=56); study group of patients with implant-supported overdentures retained with the Locator® system (n=80). The study also validated the Oral Health Impact Profile-20 questionnaire. Individual protocols were created that included socio-demographic data, the Oral Health Impact Profile-20 (OHIP-20) questionnaire and Oral Satisfaction Scale (OSS). Descriptive and bivariate statistical analysis was carried out applying χ², Pearson, Kruskal-Wallis, and Student t tests, transferring data into SPSS-Windows® software from a Microsoft® Excel spreadsheet. RESULTS: The OHIP-20 proved to be a valid instrument and provided reliable assessment of health-related quality of life among both the Spanish general population and edentulous patients. The control and study groups proved comparable, showing socio-demographic homogeneity. For patients with overdentures retained by means of the Locator® system, these restorations had significantly lower impact on quality of life (19 vs 33), both generally and for each individual questionnaire item, and much higher satisfaction with the state of their oral cavities (8.3 vs 5.3) than patients wearing dentures; both sets of data showed a direct linear relationship, so that as the level of impact on quality of life increased, perceived oral satisfaction worsened. CONCLUSIONS: Patients rehabilitated with implant supported overdentures retained by the Locator® system, presented significantly lower levels of impact on their quality of life and significantly higher oral satisfaction than patients with conventional complete prostheses.

Therapeutic solutions for discoloration of calcified teeth based on CBCT diagnosis.

Single tooth orange discoloration secondary to root canal calcification occurs as a consequence of dental trauma, orthodontic treatment, or for unknown rea- sons. A correct case history must be compiled and a CBCT study carried out in order to establish the diag- nosis and define the best treatment plan in each case. The aim of the present study was to offer a therapeutic protocol involving a clinical decision-making tree dia- gram based on the presence or absence of apical dis- ease and the degree of canal calcification. Dental bleaching and the use of ceramic veneers allow es- thetic restoration in such cases.

Accuracy of the maxillomandibular relationship at centric relation position recorded by using 3 different intraoral scanners with or without an optical jaw tracking system: An in vivo pilot study.

PURPOSE: To measure the accuracy (trueness and precision) of the maxillomandibular relationship at centric relation position recorded by using 3 different intraoral scanners with or without an optical jaw tracking system. MATERIAL AND METHODS: A completely dentate volunteer was selected. Seven groups were generated: conventional procedure (control group), 3 IOSs: Trios4 (Trios4 group), Itero Element 5D Plus (Itero group), i700 (i700 group), and 3 groups with a jaw tracking system for each corresponding IOS system (Modjaw-Trios4, Modjaw-iTero, and Modjaw-i700 groups) (n = 10). In the control group, casts were mounted on an articulator (Panadent) using a face bow and a CR record captured with the Kois deprogrammer (KD). The casts were digitized by using a scanner (T710) (control files). In the Trios4 group, intraoral scans were obtained by using the corresponding IOS and duplicated 10 times. The KD was used to obtain a bilateral occlusal record at CR position. These same procedures were followed for the Itero and i700 groups. In the Modjaw-Trios 4 group, the intraoral scans acquired by using the corresponding IOS at MIP were imported into the jaw tracking program. The KD was used to record the CR relationship. For acquiring the specimens in the Modjaw-Itero and Modjaw-i700 groups, the same procedures were followed as in the Modjaw-Trios4 group, with the scans obtained with the Itero and i700 scanners respectively. The articulated virtual casts of each group were exported. Thirty-six inter-landmark linear measurements were used to calculate the discrepancies between the control and experimental scans. The data were analyzed by using 2-way ANOVA followed the pairwise comparison Tukey tests (α=0.05). RESULTS: Significant trueness and precision discrepancies were found among the groups tested (P<.001). The Modjaw-i700, Modjaw-iTero, Modjaw-Trios4, and i700 groups obtained the best trueness and precision among the groups tested, and the iTero and Trios4 groups obtained the worst trueness. The iTero group obtained the worst precision among the groups tested (P>.05). CONCLUSIONS: The maxillomandibular relationship recorded was influenced by the technique selected. Except for the i700 IOS system, the optical jaw tracking system tested improved the trueness value of the maxillomandibular relationship recorded at CR position when compared with the corresponding IOS.

Influence of type of restorative materials and surface wetness conditions on intraoral scanning accuracy.

OBJECTIVES: To assess the influence of different restorative materials and surface wetness on intraoral scanning accuracy. METHODS: Reference casts with an extracted second premolar and first and second molar were digitized (L2). Four groups were established according to the material of the first molar: natural tooth (control), zirconia (Z), lithium disilicate (LD), and nanoceramic resin crown (NC). Four subgroups were developed: dry, low-, mild-, and high-wetness subgroups (n = 15). All the scans were completed by using an intraoral scanner (TRIOS 3). In the control-dry subgroup, the reference cast was dry. In the control-low subgroup, artificial saliva was sprayed with a 1 mL/min volumetric flow for 4 s. In the control-mild and control-high subgroups, the same procedures as in the control-low subgroup were performed, but with a volumetric flow of 4 and of 8 mL/min, respectively. In the Z, LD and NC groups, each crown was fabricated with its respective material. Trueness was analyzed using 2-way ANOVA and Bonferroni tests. The Levene and Bonferroni tests were used to assess precision (α = 0.05). RESULTS: Material (P < .001) and wetness (P < .001) significantly influenced trueness and precision. The mild and high subgroups revealed lower trueness and precision compared with the dry and low subgroups. The control, Z, and LD groups under dry and low wetness conditions showed better trueness compared with the NC group, but the materials tested had no significant precision discrepancies. Under mild wetness conditions, all the materials showed no significant trueness discrepancies. Under high wetness conditions, the LD group demonstrated the best trueness and precision. CONCLUSIONS: The restorative materials and surface wetness tested influenced scanning trueness and precision of the IOS assessed. CLINICAL SIGNIFICANCE: Dried surfaces are recommended to maximize the scanning accuracy values of the IOS tested. Overall, the presence of saliva and dental restorations can reduce the performance of the IOS tested.

Microtensile Bond Strength of CAD-CAM Restorative Dental Material Blocks to Resin Cement: An In Vitro Study.

INTRODUCTION: Today's dentistry frequently employs bonded partial restorations, which are usually fabricated in ceramic materials. In the last decade, hybrid materials have emerged that attempt to combine the properties of composites and ceramics. OBJECTIVES: To evaluate in vitro, by means of a microtensile test, the bond strength between CAD-CAM restorative materials and the cement recommended by their manufacturer. MATERIAL AND METHOD: From blocks of CAD-CAM restorative material bonded to composite blocks (Filtek 500®), beams with a bonding area of approximately 1 mm2 were made and divided into four groups: EMAX (IPS e.max CAD® lithium disilicate), VE (VITA Enamic® polymer-infiltrated ceramic matrix), LUA (Lava Ultimate® nano-ceramic resin with sandblasting protocol) and LUS (Lava Ultimate® nano-ceramic resin with silica coating protocol). In each group, perimeter (external) or central (internal) beams were differentiated according to the position in the block. The samples were tested on the LMT 100® microtensile machine. Using optical microscopy, the fractures were categorized as adhesive or cohesive (of the restorative material or composite), and the data were analysed with parametric tests (ANOVA). RESULTS: The LUS group had the highest results (42 ± 20 MPa), followed by the LUA group (38 ± 18 MPa). EMAX had a mean of 34 ± 16 MPa, and VE was the lowest in this study (30 ± 17 MPa). In all groups, the central beams performed better than the perimeter beams. Both EMAX and VE had the most adhesive fractures, while LUA and LUS had a predominance of cohesive fractures. CONCLUSIONS: Lava Ultimate® nanoceramic resin with the silica coating protocol obtains the best bond strength values.

Implant-Supported Fixed Partial Dentures with Posterior Cantilevers: In Vitro Study of Mechanical Behavior.

Rehabilitation with dental implants is not always possible due to the lack of bone quality or quantity, in many cases due to bone atrophy or the morbidity of regenerative treatments. We find ourselves in situations of performing dental prostheses with cantilevers in order to rehabilitate our patients, thus simplifying the treatment. The aim of this study was to analyze the mechanical behavior of four types of fixed partial dentures with posterior cantilevers on two dental implants (convergent collar and transmucosal internal connection) through an in vitro study (compressive loading and cyclic loading). This study comprised four groups (n = 76): in Group 1, the prosthesis was screwed directly to the implant platform (DS; n = 19); in Group 2, the prosthesis was screwed to the telescopic interface on the implant head (INS; n = 19); in Group 3, the prosthesis was cemented to the telescopic abutment (INC; n = 19); and in Group 4, the prosthesis was cemented to the abutment (DC; n = 19). The sets were subjected to a cyclic loading test (80 N load for 240,000 cycles) and compressive loading test (100 KN load at a displacement rate of 0.5 mm/min), applying the load until failure occurred to any of the components at the abutment-prosthesis-implant interface. Subsequently, an optical microscopy analysis was performed to obtain more data on what had occurred in each group. Results: Group 1 (direct screw-retained prosthesis, DS) obtained the highest mean strength value of 663.5 ± 196.0 N. The other three groups were very homogeneous: 428.4 ± 63.1 N for Group 2 (INS), 486.7 ± 67.8 N for Group 3 (INC), and 458.9 ± 38.9 N for Group 4 (DC). The mean strength was significantly dependent on the type of connection (p < 0.001), and this difference was similar for all of the test conditions (cyclic and compressive loading) (p = 0.689). Implant-borne prostheses with convergent collars and transmucosal internal connections with posterior cantilevers screwed directly to the implant connection are a good solution in cases where implant placement cannot avoid extensions.

Facial scanning accuracy depending on the alignment algorithm and digitized surface area location: An in vitro study.

OBJECTIVES: To measure the accuracy (trueness and precision) of a facial scanner depending on the alignment method and the digitized surface area location. METHODS: Fourteen markers were adhered on a head mannequin and digitized using an industrial scanner (GOM Atos Q 3D 12 M; Carl Zeiss Industrielle Messtechnik GmbH). A control mesh was acquired. Subsequently, the mannequin was digitized using a facial scanner (Arc4; Bellus3D) (n = 30). The control mesh was delineated into 10 areas. Based on the alignment procedures, two groups were created: reference best fit (RBF group) and landmark-based best fit (LA group). The root mean square was used to calculate the discrepancy between the control mesh and each facial scan. A 2-way ANOVA and Tukey pairwise comparison tests were used to compare trueness and precision between the 2 groups across 10 areas (α = .05). RESULTS: Both alignment algorithms (P = .007) and digitized area (P < .001) were significant predictors of trueness with a significant interaction between the two predictors (F (9, 580) =25.13, P < .001). Tukey pairwise comparison showed that there was a significant difference between mean trueness values of RBF (mean=0.53 mm) and LA (mean=0.55 mm) groups. Moreover, a significant difference was detected among the trueness values across surface areas. The A9-area (left tragus area) had the highest and A5-area (right cheek area) had the lowest mean trueness. Both alignment algorithm (P < .001) and digitized surface area (P < .001) were significant predictors of precision with a significant interaction between the two predictors (F (9, 580) =14.34, P < .001). Tukey pairwise comparison showed that there was a significant difference between mean precision values of RBF (mean=0.38 mm) and LA (mean=0.35 mm) groups. Moreover, a significant difference was detected among the precision values across surface areas. Comparing the surface areas, A9-area had the highest and A10-area (forehead area) had the lowest mean precision. CONCLUSIONS: Alignment procedures influenced on the scanning trueness and precision mean values, but the facial scanner accuracy values obtained were within the clinically acceptable accuracy threshold of less or equal than 2 mm. Furthermore, the scanning accuracy (for both trueness and precision) depended on the location of the scanned surface area, being more accurate on the middle of the face than on the sides of the face.

Peri-Implant Behavior of Tissue Level Dental Implants with a Convergent Neck.

INTRODUCTION: The aim of this retrospective study was to analyze the radiographic peri-implant bone loss of bone level implants and tissue level implants with a convergent neck in screw-retained single crowns and in screw-retained fixed partial prostheses, after two years of functional loading. MATERIALS AND METHODS: The sample was divided into two groups according to their type: Group I: supracrestal implants with convergent transmucosal neck; Group II: crestal implants. In each group we distinguish two subgroups according to the type of prosthetic restoration: single crowns and a three-piece fixed partial prosthesis on two implants. To quantify bone loss, parallelized periapical radiographs were analyzed at the time of implant placement and after two years of functional load. RESULTS: A total of 120 implants were placed in 53 patients. After statistical analysis it was observed that for each type of implant bone loss was 0.97 ± 0.91 mm for bone level and 0.31 ± 0.48 mm for tissue level. No significant differences were found regarding the type of prosthesis and the location (maxilla or mandible) of the implants. CONCLUSIONS: Tissue level implants with a convergent transepithelial neck exhibit less peri-implant bone loss than bone level implants regardless of the type of prosthesis.

Systematic review of chewing simulators: Reality and reproducibility of in vitro studies.

BACKGROUND: The aim of this systematic review was to analyze the types of human chewing simulator described in scientific literature. MATERIAL AND METHODS: An electronic search was conducted in the databases PubMed, Embase and Scopus. The search strategy included 10 search terms: "in vitro"; "dental materials"; "shear strength"; "fatigue fracture"; "bite force"; "prosthetic materials"; "chewing simulator"; "chewing machine"; "simulated mastication"; and "dental wear simulator." Two researchers worked independently to assess the titles and abstracts of the articles. The quality of the in vitro trials selected was evaluated by means of the Consolidated Standards of Reporting Trials scale. RESULTS: The electronic search identified 80 articles related to the topic of interest. After reading the full texts, ten works were selected. The articles focused mainly on the design of chewing simulators. Most of them were considered of moderate quality. Regarding the characteristics that an ideal chewing simulator should encompass, the devices described in articles varied greatly in terms of movement, periodontal ligament simulation, force sensors, and the materials tested. CONCLUSIONS: No chewing simulator offers all the characteristics necessary to reproduce human masticatory movements and forces under the humidity and pH conditions of the oral cavity. A simulator that encompasses all these characteristics would make it possible to standardize trials involving simulated mastication. Key words:In vitro, dental materials, dental wear simulator.

What can we do with a dental avulsion? A multidisciplinary Clinical Protocol.

PURPOSE: The aim of this case report was to explain a multidisciplinary and conservative approach carrying out the replantation of an avulsed closed apex central incisor stored in dry conditions for a 16-hour period from the moment of trauma. CASE REPORT: This report describes a case of a 28 year-old male who suffered contusion of the upper lip, avulsion of right upper central incisor, enamel cracks after trauma of left upper central incisor and upper left lateral incisor crown fracture due to an accident. Avulsed tooth was dry stored and it was replanted 16h after the trauma. The root was disinfected and the necrotic periodontal tissue removed, the endodontic treatment was done before replantation and a flexible splint was applied to tooth 13 to tooth 23. Two months later a contralateral tooth presented crown discoloration occurred due to pulp necrosis an endodontic treatment as well as bleaching were carried out. An esthetic restoration for lateral incisor crown fracture was also done. In the one year review the patient remains asymptomatic, with no signs of root resorption or ankylosis of the damaged teeth. CONCLUSIONS: A conservative approach of tooth with delayed reimplantation can be a stable and functional with the appropriate treatment procedures. A clinical protocol for patients and professionals for the treatment of the avulsed tooth is proposed. Key words:Endodontics, dental avulsion, avulsed tooth protocol.