Fracture Resistance of a Bone-Level Two-Piece Zirconia Oral Implant System-The Influence of Artificial Loading and Hydrothermal Aging.

Preclinical and clinical research on two-piece zirconia implants are warranted. Therefore, we evaluated the in vitro fracture resistance of such a zirconia oral implant system. The present study comprised 32 two-piece zirconia implants and abutments attached to the implants using a titanium (n = 16) or a zirconia abutment screw (n = 16). Both groups were subdivided (n = 8): group T-0 comprised implants with a titanium abutment screw and no artificial loading; group T-HL was the titanium screw group exposed to hydro-thermomechanical loading in a chewing simulator; group Z-0 was the zirconia abutment screw group with no artificial loading; and group Z-HL comprised the zirconia screw group with hydro-thermomechanical loading. Groups T-HL and Z-HL were loaded with 98 N and aged in 85 °C hot water for 107 chewing cycles. All samples were loaded to fracture. Kruskal-Wallis tests were executed to assess the loading/bending moment group differences. The significance level was established at a probability of 0.05. During the artificial loading, there was a single occurrence of an implant fracture. The mean fracture resistances measured in a universal testing machine were 749 N for group T-0, 828 N for group Z-0, 652 N for group T-HL, and 826 N for group Z-HL. The corresponding bending moments were as follows: group T-0, 411 Ncm; group Z-0, 452 Ncm; group T-HL, 356 Ncm; and group Z-HL, 456 Ncm. There were no statistically significant differences found between the experimental groups. Therefore, the conclusion was that loading and aging did not diminish the fracture resistance of the evaluated implant system.

Effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials: An in vitro investigation.

The aim of the study was to evaluate the effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials [CERASMART (GC); VITA ENAMIC (VITA Zahnfabrik); Lava Ultimate (3 M)] in comparison to feldspar ceramic (VITABLOCS Mark II, VITA Zahnfabrik) and resin composite materials (ceram.x universal, Dentsply Sirona). Daily brushing and acid exposure were simulated using a brushing apparatus and a solution of 0.5 vol% citric acid. Microhardness, surface roughness, and substance loss were measured at baseline and after simulation of 1 and 3 years of function. All materials showed a decrease in microhardness after 3 years and an increase in surface roughness (Ra) after 1 and 3 years. The Ra increase was statistically significantly lower for the resin-matrix ceramics than for feldspar ceramic and similar to composite material. After 3 years, only feldspar ceramic showed no significant substance loss. In conclusion, resin-matrix ceramics demonstrate reduced roughening compared to feldspar ceramics, potentially improving restoration longevity by preventing plaque buildup, but differences in abrasion resistance suggest the need for further material-specific research. Future research should aim to replicate clinical conditions closely and to transition to in vivo trials.

Bonding Strength of Various Luting Agents between Zirconium Dioxide Crowns and Titanium Bonding Bases after Long-Term Artificial Chewing.

The use of hybrid abutment crowns bonded extraorally to a titanium bonding base has aesthetic and biological benefits for the prosthetic rehabilitation of oral implants. The objective of this study was to evaluate the effects of luting agents between a zirconium dioxide crown and the titanium bonding base on crown/abutment retention and the subsequent durability of the prosthetic superstructure. Fifty-six implant abutment samples, all restored with a lower first premolar zirconium dioxide crown, were used and divided into seven groups (n = 8/group) according to the type of luting agent used: group 1, SpeedCEM Plus; group 2, Panavia SA Cement Universal; group 3, Panavia V5; group 4, RelyX Unicem 2 Automix; group 5, VITA ADIVA IA-Cem; group 6, Ketac CEM; and group 7, Hoffmann's Phosphate Cement. All specimens were subjected to thermomechanical loading (load of 49 N, 5 million chewing cycles and 54.825 thermocycles in water with temperatures of 5 °C and 55 °C). The surviving samples were exposed to a pull-off force until crown debonding from the bonding base. Overall, 55 samples survived the thermomechanical load. Group 2 showed the highest mean pull-off force value (762 N), whereas group 6 showed the lowest mean value (55 N). The differences between the seven groups were statistically significant (ANOVA, p < 0.001). The debonding failure pattern was mainly adhesive and was noticed predominantly at the zirconium dioxide-luting agent interface. Within the scope of the present investigation, it was shown that most of the luting agents are suitable for "cementation" of a zirconium dioxide crown onto a titanium base since the debonding forces are above a recommended value (159 N).

Accuracy of Computerized Optical Impression Making in Fabrication of Removable Dentures for Partially Edentulous Jaws: An In Vivo Feasibility Study.

The use of computerized optical impression making (COIM) for the fabrication of removable dentures for partially edentulous jaws is a rising trend in dental prosthetics. However, the accuracy of this method compared with that of traditional impression-making techniques remains uncertain. We therefore decided to evaluate the accuracy of COIM in the context of partially edentulous jaws in an in vivo setting. Twelve partially edentulous patients with different Kennedy classes underwent both a conventional impression (CI) and a computerized optical impression (COI) procedure. The CI was then digitized and compared with the COI data using 3D analysis software. Four different comparison situations were assessed: Whole Jaw (WJ), Mucosa with Residual Teeth (M_RT), Isolated Mucosa (IM), and Isolated Abutment Teeth (AT). Statistical analyses were conducted to evaluate group differences by quantifying the deviation values between the CIs and COIs. The mean deviations between the COIs and CIs varied significantly across the different comparison situations, with mucosal areas showing higher deviations than dental hard tissue. However, no statistically significant difference was found between the maxilla and mandible. Although COIM offers a no-pressure impression method that captures surfaces without irritation, it was found to capture mucosa less accurately than dental hard tissue. This discrepancy can likely be attributed to software algorithms that automatically filter out mobile tissues. Clinically, these findings suggest that caution is required when using COIM for prosthetics involving mucosal tissues as deviations could compromise the fit and longevity of the prosthetic appliance. Further research is warranted to assess the clinical relevance of these deviations.

Computerized optical scanning of ears: An in vitro evaluation with an intraoral scanner.

STATEMENT OF PROBLEM: Making conventional facial impressions can be uncomfortable for the patient and complicated for the prosthodontist. Using facial scanners to digitize faces is an alternative approach. However, the initial costs of the equipment have prevented their widespread use in dental practice, and the accuracy of ear scanning is unclear. PURPOSE: The purpose of this in vitro study was to investigate the accuracy of a widely used intraoral scanner for digitizing an ear model. MATERIAL AND METHODS: For reference, a silicone model of an ear was scanned with an industrial scanner. Then, the model was scanned 5 times with an intraoral scanner. Five conventional impressions of the model were made with a hydrocolloid impression material and poured with dental stone. The stone casts were then digitized with a desktop scanner. The data sets acquired with the 3 approaches were analyzed by using a 3-dimensional (3D) evaluation software program. Trueness and precision values were calculated for each approach. Linear mixed models with random intercepts were fitted to each sample to evaluate the effects of the impression method on mean deviations (α=.05). RESULTS: Mean ±standard deviation trueness and precision values were 0.097 ±0.012 mm and 0.033 ±0.015 mm, respectively, for the digital scan, and 0.092 ±0.022 mm and 0.081 ±0.024 mm for the conventional impression, showing a significantly lower deviation in precision for the digital approach (P<.001). CONCLUSIONS: The feasibility of digitizing an ear efficiently by using the investigated intraoral scanner was demonstrated, and similar trueness and significantly better precision values were achieved than when using conventional impressions. These promising results suggest the need for clinical investigations.

Case Report: Dental treatment for an oboist: Post-trauma prosthetic rehabilitation and evaluation of musical performance.

Introduction: The condition of teeth and function of the oral organs are important when playing wind or brass instruments. Although there are some reports on dental treatment for musicians, few studies have investigated their acoustic performance following treatment. This report describes the prosthodontic rehabilitation provided for an oboist who had lost a tooth as a result of trauma and includes an evaluation of her subsequent musical performance using acoustic analyzes. Case description: The patient was a 63-year-old professional oboe player who fractured the upper and lower alveolar bone and avulsed the upper right central incisor during a fall due to epileptic seizure. While the alveolar fracture was healing, she sought maxillofacial rehabilitation for the missing tooth to maintain her ability to play the oboe. Her rehabilitation consisted of a provisional removable prosthesis with an acrylic base and clasps followed by a fixed implant prosthesis. A recording of her musical performance was objectively analyzed at each stage of treatment. Rhythm analysis confirmed the stability of notes played rapidly. Her performance dynamics were analyzed by psychoacoustic measurements. Her satisfaction with the prosthesis was assessed by a self-reported questionnaire. The results of the acoustic evaluation helped to adjust the provisional prosthesis so that it was suitable for playing the oboe and the final prosthesis was designed accordingly. Conclusion: Prosthetic dental treatment for this patient included both subjective and objective evaluations that helped to ensure that she could continue playing the oboe at her previous performance level.

Clinical Performance of CAD/CAM All-Ceramic Tooth-Supported Fixed Dental Prostheses: A Systematic Review and Meta-Analysis.

Although CAD/CAM ceramics present a promising alternative to metal-ceramic fixed dental prostheses, little is known about their mid- and long-term clinical performance. This systematic review aims to estimate the survival and success rates and describes the underlying complication characteristics for CAD/CAM tooth-supported zirconia- and lithium disilicate-based fixed dental prostheses (FDPs). We systematically searched MEDLINE and Web of Science to find relevant prospective studies with a follow-up of at least one year. We estimated pooled 1-, 5-, and 10-year survival and success rates by combining the collected data in a Poisson regression model. Descriptive statistics were conducted to evaluate the distribution of failures and complications in the included studies. Risk of bias for the included studies was assessed with an adapted checklist for single-arm trials. Pooled estimated 1-, 5-, and 10-year survival rates ranged from 93.80% to 94.66%, 89.67% to 91.1%, and 79.33% to 82.20%, respectively. The corresponding success rates excluding failures, but including any other types of intervention were 94.53% to 96.77%, 90.89% to 94.62%, and 81.78% to 89.25%. Secondary caries was the most frequent cause of failure, followed by chipping of the veneering. The most common cause of complication excluding failures but requiring intervention was chipping of the veneering. Risk of bias was generally acceptable for the included studies, with seven studies associated with low risk of bias, eight studies with a moderate risk of bias, and three studies with serious risk of bias. The current meta-analysis on CAD/CAM-supported FDPs revealed satisfying survival and success rates for up to 10 years of exposure. More prospective studies focusing on long-term performance are needed to strengthen the evidence currently available in the literature.

Computerized optical impression making of edentulous jaws - An in vivo feasibility study.

PURPOSE: Within the specialty of prosthodontics, oral impressions are ubiquitous tools utilized to transfer intraoral characteristics such as teeth, implants, and soft tissue into a physical state (stone cast) that is processable in a laboratory setting for the fabrication of dental restorations. In recent years, optical impression systems have become ubiquitous in clinical practice replacing the conventional method of impression making. The purpose of the present study was to evaluate the feasibility and accuracy of computerized optical impression making of edentulous jaws in an in vivo setting. METHODS: 29 edentulous patients (27 maxillae and five mandibles) underwent conventional impressions as well as computerized optical impressions. The conventional impressions and the resulting stone casts were digitized and superimposed over the computerized/digitized optical impressions in order to obtain information on differences between the two datasets. Statistical analyses were performed to identify relevant deviations. RESULTS: The overall mean difference between the stone cast, digital scans and the computerized optical scans were 336.7 ± 105.0 µm (n = 32), 363.7 ± 143.1 µm (n = 24), and 272.1 ± 168.5 µm (n = 29), respectively. The visual evaluations revealed highest deviations (≥ 500 µm) in the areas of the soft palate, the sublingual areas, and the vestibule (peripheral seal zone). CONCLUSIONS: Within the limitations of the present study, the investigated scanners were not able currently to fully replace a conventional impression for the fabrication of a complete denture.

Comparison of Dental Students' Self-Directed, Faculty, and Software-Based Assessments of Dental Anatomy Wax-Ups: A Retrospective Study.

Little is known about self-directed and self-reflective assessment in preclinical dental curricula. The aim of this study was to evaluate a visual dental anatomy teaching tool to train dental students to self-assess their dental anatomy wax carving practical examinations. The students self-assessed two waxing practical examinations (tooth #8 and tooth #19) using high-quality digital images in an assessment tool incorporated into a digital testing program. Student self-assessments were compared to the faculty evaluations and the results of a software-based evaluation tool (E4D Compare). Out of a total 130 first-year dental students at one U.S. dental school, wax-ups from 57 participants were available for this study. The assessment data were submitted to statistical analyses (p<0.05). For tooth #8, the student self-assessments were significantly different from the faculty and software assessments at a 400 micrometer level of tolerance (p=0.036), whereas the faculty assessment was not significantly different from the software assessment at a 300 micrometer level of tolerance (p=0.69). The evaluation of tooth #19 resulted in no significant differences between faculty members (p=0.94) or students (p=0.21) and the software at a level of tolerance of 400 micrometers. This study indicates that students can learn to self-assess their work using self-reflection in conjunction with faculty guidance and that it may be possible to use software-based evaluation tools to assist in faculty calibration and as objective grading tools.

Digital technologies to support planning, treatment, and fabrication processes and outcome assessments in implant dentistry. Summary and consensus statements. The 4th EAO consensus conference 2015.

OBJECTIVE: The task of this working group was to assess the existing knowledge in computer-assisted implant planning and placement, fabrication of reconstructions applying computers compared to traditional fabrication, and assessments of treatment outcomes using novel imaging techniques. MATERIAL AND METHODS: Three reviews were available for assessing the current literature and provided the basis for the discussions and the consensus report. One review dealt with the use of computers to plan implant therapy and to place implants in partially and fully edentulous patients. A second one focused on novel techniques and methods to assess treatment outcomes and the third compared CAD/CAM-fabricated reconstructions to conventionally fabricated ones. RESULTS: The consensus statements, the clinical recommendations, and the implications for research, all of them after approval by the plenum of the consensus conference, are described in this article. The three articles by Vercruyssen et al., Patzelt & Kohal, and Benic et al. are presented separately as part of the supplement of this consensus conference.

Software-based evaluation of human age: a pilot study.

PURPOSE: This pilot study was to assess a smartphone application regarding its use as an objective evaluation tool for subject age in comparison to human raters and to identify potential factors influencing the estimation of age. MATERIALS AND METHODS: Ten Caucasian participants (six females, four males, mean age 42.1 ± 22.6 years) were randomly chosen, and frontal facial pictures of each participant were taken. The smartphone application PhotoAge (Version 1.5, ©2012, Percipo Inc., San Francisco, CA, USA) was used to evaluate the age of the participants. For comparison, 100 randomly selected raters (60 females, 40 males, mean age 29.3 ± 1.3 years) were asked to evaluate the age of the same participants. The influence of participants' facial expression, age, and sex as well as raters' age, sex, and profession was investigated as well. Statistical analyses (linear mixed models with random intercepts; least square means, confidence interval 95%; p < 0.05) were implemented. RESULTS: PhotoAge resulted in a mean age of 43.1 ± 18.2 years, with a difference from the true mean age of 1.0 ± 8.2 years (p = 0.5996). The evaluation by the raters revealed a mean age of 41.5 ± 19.0 years, with a difference from the true mean age of -0.6 ± 8.5 years (p = 0.6078). There was no statistical significance between the two groups (p = 0.2783). CONCLUSION: The evaluation of age with the software application PhotoAge seems to be a reliable procedure with comparable results to human raters. CLINICAL SIGNIFICANCE: This study gives a better understanding about the reliability of a software-based evaluation tool for age and identifies factors (e.g., the visibility of the teeth) potentially affecting the estimation of age. Naturally looking teeth seem to have no influence on the evaluation of a person's age. Thus, the application of this specific application for dental purposes is questionable; however, in forensics, it might be a valuable tool for estimating a person's age.

Accuracy of computer-aided design/computer-aided manufacturing-generated dental casts based on intraoral scanner data.

BACKGROUND: Little is known about the accuracy of physical dental casts that are based on three-dimensional (3D) data from an intraoral scanner (IOS). Thus, the authors conducted a study to evaluate the accuracy of full-arch stereolithographic (SLA) and milled casts obtained from scans of three IOSs. METHODS: The authors digitized a polyurethane model using a laboratory reference scanner and three IOSs. They sent the scans (n = five scans per IOS) to the manufacturers to produce five physical dental casts and scanned the casts with the reference scanner. Using 3D evaluation software, the authors superimposed the data sets and compared them. RESULTS: The mean trueness values of Lava Chairside Oral Scanner C.O.S. (3M ESPE, St. Paul, Minn.), CEREC AC with Bluecam (Sirona, Bensheim, Germany) and iTero (Align Technology, San Jose, Calif.) casts were 67.50 micrometers (95 percent confidence interval [CI], 63.43-71.56), 75.80 µm (95 percent CI, 71.74-79.87) and 98.23 µm (95 percent CI, 94.17-102.30), respectively, with a statistically significant difference among all of the scanners (P < .05). The mean precision values were 13.77 µm (95 percent CI, 2.76-24.79), 21.62 µm (95 percent CI, 10.60-32.63) and 48.83 µm (95 percent CI, 37.82-59.85), respectively, with statistically significant differences between CEREC AC with Bluecam and iTero casts, as well as between Lava Chairside Oral Scanner C.O.S. and iTero casts (P < .05). CONCLUSION: All of the casts showed an acceptable level of accuracy; however, the SLA-based casts (CEREC AC with Bluecam and Lava Chairside Oral Scanner C.O.S.) seemed to be more accurate than milled casts (iTero). PRACTICAL IMPLICATIONS: On the basis of the results of this investigation, the authors suggested that SLA technology was superior for the fabrication of dental casts. Nevertheless, all of the investigated casts showed clinically acceptable accuracy. Clinicians should keep in mind that the highest deviations might occur in the distal areas of the casts.

Software-based evaluation of human attractiveness: a pilot study.

STATEMENT OF PROBLEM: The difficulty of evaluating esthetics in an unbiased way may be overcome by using automated software applications. PURPOSE: The purpose of this study was to assess the use of a smartphone application as an objective tool for evaluating attractiveness and to evaluate its potential in dentistry. MATERIAL AND METHODS: Ten white participants (mean age ±SD, 42.1 ±22.6 years) were randomly chosen, and frontal facial pictures of each participant were made. The smartphone application PhotoGenic was used to evaluate the attractiveness of the participants. For comparison, 100 randomly (age>16 years, social environment of the research team) selected raters were asked to evaluate the same participants. The influence of participants' facial expression, age, and sex as well as the raters' age, sex, and occupation was investigated. Statistical analyses (linear mixed models with random intercepts; least square means, 95% confidence interval; P<.05) were implemented. RESULTS: PhotoGenic produced a mean ±SD attractiveness score of 6.4 ±1.2 and the rater group of 4.9 ±1.8 (P<.001; score range, 0-10). Female raters tended to slightly higher attractiveness scores. The participants' sex, facial expression, and age seemed to not be of high relevance; however, the raters' sex and occupation had an impact on the evaluation. CONCLUSION: PhotoGenic rated the participants' attractiveness with higher scores (more attractive) than did the human raters. Currently, PhotoGenic is not used as an objective evaluation tool for treatment outcomes for dental treatments because the visibility of the teeth (smiling facial expression) has no influence on the evaluation.

The time efficiency of intraoral scanners: an in vitro comparative study.

BACKGROUND: Although intraoral scanners are known to have good accuracy in computer-aided impression making (CAIM), their effect on time efficiency is not. Little is known about the time required to make a digital impression. The purpose of the authors' in vitro investigation was to evaluate the time efficiency of intraoral scanners. METHODS: The authors used three different intraoral scanners to digitize a single abutment (scenario 1), a short-span fixed dental prosthesis (scenario 2) and a full-arch prosthesis preparation (scenario 3). They measured the procedure durations for the several scenarios and compiled and contrasted the procedure durations for three conventional impression materials. RESULTS: The mean total procedure durations for making digital impressions of scenarios 1, 2 and 3 were as much as 5 minutes 57 seconds, 6 minutes 57 seconds, and 20 minutes 55 seconds, respectively. Results showed statistically significant differences between all scanners (P < .05), except Lava (3M ESPE, St. Paul, Minn.) and iTero with foot pedal (Align Technology, San Jose, Calif.) for scenario 1, CEREC (Sirona, Bensheim, Germany) and CEREC with foot pedal for scenario 2, and iTero and iTero with foot pedal for scenarios 2 and 3. The compiled procedure durations for making conventional impressions in scenarios 1 and 2 ranged between 18 minutes 15 seconds and 27 minutes 25 seconds; for scenario 3, they ranged between 21 minutes 25 seconds and 30 minutes 25 seconds. CONCLUSIONS: The authors found that CAIM was significantly faster for all tested scenarios. This suggests that CAIM might be beneficial in establishing a more time-efficient work flow. PRACTICAL IMPLICATIONS: On the basis of the results of this in vitro study, the authors found CAIM to be superior regarding time efficiency in comparison with conventional approaches and might accelerate the work flow of making impressions.

Summary of: attitudes of general dental practitioners to the maintenance of Locator retained implant overdentures.

INTRODUCTION: Locator retained implant overdentures are associated with a high incidence of prosthodontic complications. This study investigated whether general dental practitioners (GDPs) were willing to maintain these prostheses in primary dental care. METHOD: A questionnaire was distributed to all GDPs referring patients for an implant assessment to the Charles Clifford Dental Hospital, Sheffield between 1 January 2012 and 30 June 2012. RESULTS: Ninety-four out of one hundred and forty-six questionnaires were returned (response rate: 64%). Thirteen GDPs (14%) were able to identify the Locator attachment system from clinical photographs. Eighty-two GDPs (87%) would adjust the fit surface of a Locator retained implant overdenture. Twenty-three GDPs (25%) would replace a retentive insert, 18 GDPs (19%) would tighten a loose abutment, 68 GDPs (72%) would debride abutments and 25 GDPs (27%) would remake a Locator-retained implant overdenture. Forty-seven GDPs (50%) felt that the maintenance of these prostheses was not their responsibility. The main barriers identified to maintenance by GDPs were a lack of training, knowledge and equipment. Seventy GDPs (74%) would like further training in this area. CONCLUSIONS: GDPs are not familiar with the Locator attachment system and are reluctant to maintain implant retained overdentures. GDPs would like further training in this area.

The all-on-four treatment concept: a systematic review.

PURPOSE: The study aims to evaluate the all-on-four treatment concept with regard to survival rates (SRs) of oral implants, applied fixed dental prostheses (FDPs) and temporal changes in proximal bone levels. MATERIALS AND METHODS: A systematic review of publications in English and German was performed using the electronic bibliographic database MEDLINE, the Cochrane Library, and Google. Hand searches were conducted of the bibliographies of related journals and systematic reviews. The authors performed evaluations of articles independently, as well as data extraction and quality assessment. Data were submitted the weighted least-squared analysis. RESULTS: Thirteen (487 initially identified) papers met inclusion criteria. A number of 4,804 implants were initially placed, of which 74 failed, with a majority of failures (74%) within the first 12 months. A total of 1,201 prostheses were incorporated within 48 hours after the surgery. The major prosthetic complication was the fracture of the all-acrylic FDP. The mean cumulative SR/SR ± (standard deviation) (36 months) of implants and prostheses were 99.0 ± 1.0% and 99.9 ± 0.3%, respectively. The averaged bone loss was 1.3 ± 0.4 mm (36 months). No statistically significant differences were found in outcome measures, when comparing maxillary versus mandibular arches and axially versus tilted placed implants. CONCLUSION: The available data provide promising short-term results for the all-on-four treatment approach; however, current evidence is limited by the quality of available studies and the paucity of data on long-term clinical outcomes of 5 years or greater. In terms of an evidence-based dentistry, the authors recommend further studies designed as randomized controlled clinical trials and reported according to the CONSORT statement.

Accuracy of full-arch scans using intraoral scanners.

OBJECTIVES: This study aimed to evaluate the accuracy of intraoral scanners in full-arch scans. MATERIALS AND METHODS: A representative model with 14 prepared abutments was digitized using an industrial scanner (reference scanner) as well as four intraoral scanners (iTero, CEREC AC Bluecam, Lava C.O.S., and Zfx IntraScan). Datasets obtained from different scans were loaded into 3D evaluation software, superimposed, and compared for accuracy. One-way analysis of variance (ANOVA) was implemented to compute differences within groups (precision) as well as comparisons with the reference scan (trueness). A level of statistical significance of p < 0.05 was set. RESULTS: Mean trueness values ranged from 38 to 332.9 µm. Data analysis yielded statistically significant differences between CEREC AC Bluecam and other scanners as well as between Zfx IntraScan and Lava C.O.S. Mean precision values ranged from 37.9 to 99.1 µm. Statistically significant differences were found between CEREC AC Bluecam and Lava C.O.S., CEREC AC Bluecam and iTero, Zfx Intra Scan and Lava C.O.S., and Zfx Intra Scan and iTero (p < 0.05). CONCLUSIONS: Except for one intraoral scanner system, all tested systems showed a comparable level of accuracy for full-arch scans of prepared teeth. Further studies are needed to validate the accuracy of these scanners under clinical conditions. CLINICAL RELEVANCE: Despite excellent accuracy in single-unit scans having been demonstrated, little is known about the accuracy of intraoral scanners in simultaneous scans of multiple abutments. Although most of the tested scanners showed comparable values, the results suggest that the inaccuracies of the obtained datasets may contribute to inaccuracies in the final restorations.

Assessing the feasibility and accuracy of digitizing edentulous jaws.

BACKGROUND: Despite the accuracy of intraoral scanners (IOSs) in producing single-unit scans and the possibility of generating complete dentures digitally, little is known about their feasibility and accuracy in digitizing edentulous jaws. The purpose of this in vitro investigation was to evaluate the feasibility and accuracy of digitizing edentulous jaw models with IOSs. METHODS: The authors used an industrial laser scanner (reference scanner) and four IOSs to digitize two representative edentulous jaw models. They loaded the data sets obtained into three-dimensional evaluation software, superimposed the data sets and compared them for accuracy. The authors used a one-way analysis of variance to compute differences within groups (precision), as well as to compare values with those of the reference scanner (trueness) (statistical significance, P < .05). RESULTS: Mean trueness values ranged from 44.1 to 591.8 micrometers. Data analysis yielded statistically significant differences in trueness between all scanners (P < .05). Mean precision values ranged from 21.6 to 698.0 µm. The study results showed statistically significant differences in precision between all scanners (P < .05), except for the CEREC AC Bluecam (Sirona, Bensheim, Germany) and the Zfx IntraScan (manufactured by MHT Italy, Negrar, Italy/ MHT Optic Research, Niederhasli, Switzerland; distributed by Zfx, Dachau, Germany) (P > .05). CONCLUSIONS: Digitizing edentulous jaw models with the use of IOSs appears to be feasible, although the accuracy of the scanners differs significantly. The results of this study showed that only one scanner was sufficiently accurate to warrant further intraoral investigations. Further enhancements are necessary to recommend these IOSs for this particular indication. Practical Implications. On the basis of the results of this study, the authors cannot recommend these four IOSs for digitization of edentulous jaws in vivo.

One-piece zirconia oral implants: one-year results from a prospective case series. 2. Three-unit fixed dental prosthesis (FDP) reconstruction.

AIM: To evaluate the clinical and radiological outcome of one-piece zirconia oral implants for three-unit fixed dental prosthesis (FDP) replacement after 1 year. MATERIALS: Twenty eight patients were recruited for the investigation and signed an informed consent. All patients were treated with a one-stage implant surgery and a three-unit immediate temporary restoration on two one-piece zirconia implants. The implants were fabricated of yttria-stabilized tetragonal zirconia (y-TZP). The endosseous part of the implants was tapered with a porous surface. A total of 56 implants were inserted in the 28 patients. A total of 12 implants were placed in the upper jaws (six in the anterior area and six in the posterior area) and 44 in mandibles (all in the posterior area). At implant insertion and after 1 year, standardized radiographs were taken to evaluate the peri-implant bone loss. To evaluate any influences from different baseline parameters on the marginal bone loss a univariate analysis was performed. Clinical soft tissue parameters probing depth (PD), clinical attachment level (CAL), modified bleeding index (mBI) and modified plaque index (mPI) were recorded. Implant cumulative survival rates were calculated using actuarial life table analysis. Changes in the clinical variables were assessed using the Wilcoxon Signed Ranks test (PD, CAL) and the Sign test (mBl, mPl). All significance tests were conducted at a 5% level of significance. RESULTS: After 1 year, one implant was lost resulting in a survival rate of 98.2%. The patient was excluded from further analysis. The marginal bone loss after 1 year amounted to 1.95 mm. In 40% of the patients a bone loss of at least 2 mm and in 28% of the patients a loss of more than 3 mm were observed. The PD decreased for implant and tooth sites over time, the values being significantly higher for implants than for teeth. Over 1 year, the CAL increased slightly around the implants and decreased around the teeth. At the 1-year follow-up, the CAL at the implant sites was statistically significantly higher than at the reference teeth. The mBI was significantly lower at implants than at teeth. The same result was found for the plaque index. CONCLUSIONS: A high frequency of increased radiographic bone loss (>2 mm) after 1 year around the presented one-piece zirconia implant system was found. The bone loss seems to be higher compared to the very limited availability of zirconia implant data. Therefore, within the limits of the present investigation, it may be concluded that the presented zirconia implant system possibly performs inferior to conventional titanium implants and to other zirconia implants regarding peri-implant bone loss.

Honoring the Admiral: Boerhaave-van Wassenaer's syndrome.

Dr. Herman Boerhaave (1668-1738) first described esophageal rupture and the subsequent mediastinal sepsis based upon his careful clinical and autopsy findings and hundreds of references have since been written about Boerhaave's syndrome. Several fine historical accounts of this brilliant scientist have been published over the years and he has received appropriate credit for his valuable contributions. But what about that unfortunate propositus that Dr. Boerhaave attended to, performed necropsy upon, and subsequently received acclaim with? Medical history pays inadequate regard to the Baron Jan Gerrit van Wassenaer heer van Rosenberg, Prefect of Rhineland and Grand Admiral of the Dutch Fleet. This figure was a nobleman and war hero at the peak of the Dutch Golden Age who played his role in steering the course of European history. Without this nobleman's heroic contemporaneous account, Boerhaave's celebrated impact on medical science would never have been realized. Therefore, we offer an overdue recitation of Admiral van Wassenaer's biography. Based on found precedent we propose that spontaneous rupture of the esophagus be henceforth referred to as the 'Boerhaave-van Wassenaer's syndrome'.