Purpose: The purpose of this review is to present a comprehensive review of the current published literature investigating the various methods and techniques for scanning, de- signing, and fabrication of CAD/CAM generated restorations along with detailing the new classifications of CAD/CAM technology. Study selection: I performed a review of a PubMed using the following search terms ‘‘CAD/ CAM, 3D printing, scanner, digital impression, and zirconia''. The articles were screened for further relevant investigations. The search was limited to articles written in English, published from 2001 to 2015. In addition, a manual search was also conducted through articles and reference lists retrieved from the electronic search and peer-reviewed journals. Results: CAD/CAM technology has advantages including digital impressions and models, and use of virtual articulators. However, the implementation of this technology is still considered expensive and requires highly trained personnel. Currently, the design software has more applications including complete dentures and removable partial denture frame- works. The accuracy of restoration fabrication can be best attained with 5 axes milling units. The 3D printing technology has been incorporated into dentistry, but does not include ceramics and is limited to polymers. In the future, optical impressions will be replaced with ultrasound impressions using ultrasonic waves, which have the capability to penetrate the gingiva non-invasively without retraction cords and not be affected by fluids. Conclusion: The coming trend for most practitioners will be the use of an acquisition camera attached to a computer with the appropriate software and the capability of forwarding the image to the laboratory.

Purpose: The Oral Health Impact Profile (OHIP) is currently the most widely used oral health- related quality of life (OHRQoL) instrument. The study validated the English-language 5-item OHIP by investigating its psychometric properties of dimensionality, reliability, and validity in the adult general population. Methods: In 405 subjects (mean age 45 + 15.7 years, 63% female) from the 2014 Minnesota State Fair, dimensionality was investigated by confirmatory factor analysis. Construct validity was assessed by using a structural equation model correlating OHRQoL and self- reported global oral health status. Reliability was calculated using Cronbach's alpha for OHIP5 total scores. Results: In the confirmatory factor analysis, the unidimensional model fit OHIP5 well as indicated by fit indices (RMSEA: 0.07, SRMR: 0.03, comparative fit indices: >0.95). In the structural equation model, self-reported global oral health status correlated with 0.46 with the latent OHRQoL factor, indicating sufficient construct validity. Cronbach's alpha, a measure of score reliability, was ‘‘satisfactory'' with 0.75. Conclusion: We validated the English-language version of OHIP5 in the adult general popu- lation. Ultrashort instruments such as the 5-item OHIP provide a conceptually appealing and technically feasible opportunity to measure the impact of oral disorders and dental inter- ventions in settings such as general dental practice where the burden to collect and interpret OHRQoL information needs to be minimized.

Purpose: This preliminary study examined whether the type of surgery performed for head and neck lesion was associated perceived chewing ability, objective masticatory function,and oral health-related quality of life (OHRQoL) in patients who required a dento-maxillary prosthesis postoperatively. Methods: Thirty-eight patients with a dento-maxillary prosthesis were divided into three groups according to the type of surgery received: marginal mandibulectomy, segmental mandibulectomy with bony reconstruction, or glossectomy. Perceived chewing ability,objective mixing ability, and OHRQoL were evaluated using a food intake questionnaire,color-changeable chewing gum, and the Geriatric Oral Health Assessment Index (GOHAI),respectively. Differences in the scores obtained by the three measures were compared between the surgical groups using the Kruskal-Wallis test, and associations between the scores in each group were analyzed by Spearman's rank correlation analysis. Results: Objective mixing ability was found to be significantly low only in patients who underwent glossectomy. No other measures differed significantly between the surgical groups. Perceived chewing ability and objective mixing ability were significantly associated in the marginal mandibulectomy and glossectomy groups but not in the segmental mandibulectomy group. Furthermore, GOHAI score was significantly associated with perceived chewing ability and objective mixing ability in the marginal mandibulectomy group. Conclusions: Within the limitations of this study, the present findings suggest that the type of surgery received might influence food mixing ability. Associations among food mixing ability, perceived chewing and OHRQoL are not accountable depending on the type of surgery received, indicating the presence of other contributing factors to be considered.

Purpose: The precision of two types of surface digitization devices, i.e., a contact probe scanner and an optical scanner, and the trueness of two types of stone replicas, i.e., one without an imaging powder (SR/NP) and one with an imaging powder (SR/P), were evaluated using a computer-aided analysis. Methods: A master die was fabricated from stainless steel. Ten impressions were taken, and ten stone replicas were prepared from Type IV stone (Fujirock EP, GC, Leuven, Belgium). The precision of two types of scanners was analyzed using the root mean square (RMS), measurement error (ME), and limits of agreement (LoA) at each coordinate. The trueness of the stone replicas was evaluated using the total deviation. A Student's t-test was applied to compare the discrepancies between the CAD-reference-models of the master die (m-CRM) and point clouds for the two types of stone replicas (a = .05). Results: The RMS values for the precision were 1.58, 1.28, and 0.98 mm along the x-, y-, and z-axes in the contact probe scanner and 1.97, 1.32, and 1.33 mm along the x-, y-, and z-axes in the optical scanner, respectively. A comparison with m-CRM revealed a trueness of 7.10 mm for SR/NP and 8.65 mm for SR/P. Conclusions: The precision at each coordinate (x-, y-, and z-axes) was revealed to be higher than the one assessed in the previous method (overall offset differences). A comparison between the m-CRM and 3D surface models of the stone replicas revealed a greater dimensional change in SR/P than in SR/NP.

Purpose: The purpose of this study was to evaluate the shear bond strength (SBS) of veneering ceramic and zirconia fabricated by the digital veneering method. Methods: A total of 50 specimens were fabricated, i.e., 10 specimens each for the metal- ceramic (control) group and the four zirconia groups. The zirconia groups comprised speci- mens fabricated by the digital veneering method, the heat pressing method, and hand layering method for two groups, respectively. Furthermore, the shear bond strength was measured with a universal testing machine (Model 3345, Instron, Canton, MA, USA) and statistically analyzed using one-way ANOVA set at a significance level of P < 0.05. The corresponding mode of failure was determined from Scanning Electron Microscope (FESEM JSM 6701F, Jeol Ltd., Japan) observations. Results: One-way analysis of variance (ANOVA) revealed that the metal-ceramic group had the highest SBS (43.62 MPa), followed by the digital veneering method (28.29 MPa), the heat pressing method (18.89 MPa), and the layering method (18.65, 17.21 MPa). The samples fabricated by digital veneering had a significantly higher SBS than the other zirconia samples (P < 0.05). All of the samples exhibited mixed failure. Conclusions: Veneering ceramic with a zirconia core that was fabricated via the digital veneering method is believed to be effective in clinical use since, its shear bond strength is significantly higher than that resulting from the conventional method.

Purpose: The purpose of this study was to investigate the possibilities of utilizing new acrylic denture base materials in resin clasps using three-point flexural tests and cantilever beam tests. Methods: Seven non-metal clasp denture (NMCD) materials and four acrylic denture base materials were used for three-point flexural tests and six NMCD materials and three acrylic denture base materials were used for cantilever beam tests. The flexural strength, elastic modulus, and 0.05% proof stress were measured by three-point flexural tests according to International Organization for Standardization (ISO) 20795-1. And load at 0.5 mm deforma- tion, elastic modulus were measured by Cantilever beam tests. Results: For the three-point flexural tests, only materials that met the conditions for both flexural strength and elastic modulus were the polycarbonate Reigning N (REN) and the acrylics Acron (AC), Pro Impact (PI), Procast DSP (PC) and IvoBase High Impact (HI) which are required in ISO 20795-1, Type 3 denture base materials. And for cantilever beam tests there was no significant difference between PI and either EstheShot (ES), EstheShot Bright (ESB), REN or Acry Tone (ACT) in load at 0.5 mm deformation, and no significant difference between PI and either Lucitone FRS (LTF), ES, ESB, REN or ACT in elastic modulus. Conclusions: The results thus suggested that some of the acrylic materials used as denture base materials may also be usable for NMCDs, and that the flexural properties of the acrylic material PI resemble those of ES, ESB and ACT, meaning that similar clasp designs may also be feasible.

Purpose: The purpose of this study is to compare the pressure dynamics in the trays caused by differences in the various impression materials and in the thickness of the relief provided for the trays. Methods: In this study, two types of polyvinylsiloxane elastomers, one type of polyether elastomer and one type of alginate impression material were used. Pressure sensors were embedded at eight locations in a model of an edentulous maxilla, and used a simulation model covered with a pseudomucosa. For each impression material, the measurement was performed five times for each of the three types of trays, and the mean values were determined. Statistical analysis was carried out using one-way analysis of variance and the Tukey's HDS method, and the various pressure sensor values for each of the impression materials were compared 10 s and 20 s after the start of the measurement. Additionally, we compared differences among the three types of trays after 20 s. Results: The pressure values for sensors placed in the relief region tended to become uniform. Furthermore, we saw a tendency for the pressure to increase at the alveolar crests of the first molars on the left and right and at the posterior border of the palate, all of which support the denture, when relief was provided. Conclusions: The above results suggest that making the final impression for the denture using the selective pressure technique, with consideration given to the pressure dynamic, may lead to a good outcome in terms of preservation of the alveolar ridge.

Purpose: Osteoporosis contributes to impaired bone regeneration and remodeling through an imbalance of osteoblastic and osteoclastic activity, and can delay peri-implant bone formation after dental implant surgery, resulting in a prolonged treatment period. It poses several difficulties for individuals with large edentulous areas, and decreases their quality of life. Consequently, prompt postoperative placement of the final prosthesis is very important clinically. Peri-implant bone formation may be enhanced by systemic approaches, such as the use of osteoporosis supplements, to promote bone metabolism. We aimed to confirm whether intake of synthetic bone mineral (SBM), a supplement developed for osteoporosis, could effectively accelerate peri-implant bone formation in a rat model of osteoporosis. Methods: Thirty-six 7-week-old ovariectomized female Wistar rats were randomly assigned to receive a standardized diet with or without SBM (Diet with SBM group and Diet without SBM group, respectively; n = 18 for both). The rats underwent implant surgery at 9 weeks of age under general anesthesia. The main outcome measures, bone mineral density (BMD) and pull-out strength of the implant from the femur, were compared at 2 and 4 weeks after implantation using the Mann-Whitney U test. Results: Pull-out strength and BMD in the Diet with SBM group were significantly greater than those in the Diet without SBM group at 2 and 4 weeks after implantation. Conclusions: This study demonstrated that SBM could be effective in accelerating peri- implant bone formation in osteoporosis.

Introduction: Regarding implant-supported prostheses, the most reported types of compli- cations are related to loosening or fracturing of abutment or prosthesis screws. This case report shows a series of procedures that allowed a conservative solution for a fractured screw. It avoided removing the implant and also allowed the same prosthesis to be used after guided-drilling the fractured screw and re-tapping the implant internal threads. The same prosthesis was replaced immediately after the procedure. Patient: A 67-year-old male patient, who had a fractured abutment screw of the lower left first molar implant. The patient decided for the conservative treatment option and an attempt was made to remove the fractured screw. Discussion: Parafunctional habits can generate excessive occlusal forces, which are risk factors associated with loosening and fracturing implant screws and even the fixtures themselves. This case report focus on the probable causes, difficulties and risks associated with this procedure and it also discusses the alternative approaches. Conclusion: The purposed treatment allowed a time and money saving resolution for fractured abutment screws.