Manufacturing of PEEK orthodontic baseplate and 3D-printed alloy components from an intraoral scan.

This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and mandibular arches. 3Shape Orthodontics Appliance Designer produced the virtual Hawley retainer, consisting of alloy components (Adam Clasps and Fitted Labial bow) and a base plate. The base plate design was modified to adapt to inserting the alloy components, which were combined using cold-cured acrylic. The finished Hawley retainer was assessed intraorally. The described technique emphasizes the design specifications of digitally designed and manufactured removable orthodontic appliances. A combination of additive and subtractive techniques was successfully employed to manufacture the alloy components and base plate. This novel method provides an alternative approach to manufacturing removable appliances with computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies. The described process offers a precursor to digital manufacturing of other developed designs of dental appliances.

Berlin and Epworth Surveys to Predict Obstructive Sleep Apnea for Adults on Biomimetic Oral Appliance Therapy: A Nonrandomized Clinical Trial.

Background: Two questionnaires (Berlin Questionnaire (BQ) and Epworth Sleepiness Scale (ESS)) are the widely used screening instruments for subjects suffering from sleep disorders. Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing. The biomimetic oral appliance therapy (BOAT) offers an alternative nonsurgical method, which can improve symptoms and indices of OSA on objective sleep testing. Aim: To describe testing the ability of BQ and EES for prediction of BOAT outcomes during OSA. Methods: Seventeen adults (9 males, 8 females; age, mean (SD): 45.76 (10.31), BMI mean (SD): 33.5(13.43)) who underwent an overnight sleep study were diagnosed by a sleep specialist physician. The BQ and EES were recorded before and after BOAT treatment. Subjects with mild-to-moderate OSA had 2 months of follow-up visits and underwent a final overnight sleep study to measure apnea-hypopnea index (AHI). The subjects were asked to wear the appliance for 10-12 hours/day and at night. Findings were analyzed statistically using paired t-tests. Result: As per sleep test results, pre-BOAT AHI measures versus post-BOAT AHI measures showed significant improvement. Comparing the BQ before versus after treatment showed that at the pretreatment stage, 66.0% of patients had high-risk score, whereas 34% had low-risk score. After treatment, 66.0% of patient had low-risk scores, whereas 34% had high-risk scores. As for the ESS, treatment resulted in significant reduction of total score from 10.43 ± 6.32 to 5.00 ± 5.20 (P < 0.01, paired t-test). Finally, there was a mild negative correlation between AHI and each of the BQ and ESS scores that was not statistically significant (r = -0.420, N = 26, P > 0.05, and r = -0.41, N = 26, P > 0.05, respectively). Conclusion: The BOAT device may provide a useful form of therapy to improve OSA-related PSG parameters such as AHI. Both BQ and ESS were predictive to improvements detected by the sleep study during BOAT device use.

Oral health knowledge and dental behavior among individuals with autism in Jordan: a case-control study.

BACKGROUND: Oral care is acknowledged as an integral component of general health and plays an essential role in establishing the desired level of quality of life for individuals with autism spectrum disorder (ASD). PURPOSE: To investigate oral health knowledge and dental behaviors in individuals with ASD in comparison with individuals without ASD in Jordan. METHODS: A case-control study was carried out among 296 caregivers of individuals with ASD (n = 147) and control (n = 149) groups. A closed ended, validated self-designed questionnaire was distributed. The questionnaire included questions addressing participant's oral health knowledge and behaviour. Data were analyzed using SPSS® software Version 22 with a 0.05 level of significance. A Chi-square test and contingency-table analysis were performed. RESULTS: Individuals with ASD in Jordan were significantly less knowledgeable about different oral health aspects than individuals without ASD (p < 0.05). Fewer individuals in the ASD group brushed their teeth once or twice daily (89%), compared to the control group (93%). Only 15% of the ASD participants could brush their teeth without help. The use of fluoridated toothpaste and the frequency of using mouth rinse demonstrated a significant difference between groups (p < 0.05). CONCLUSION: ASD individuals in Jordan suffer from a significant lack of oral knowledge comparing to their controls, leading to a misunderstanding of the basic and highly important dental health aspects. Indicating that the knowledge was not enough to influence their dental behaviors. Children with ASD and their families should receive appropriate education in special need oral health care given by oral health professionals to reduce the risk of having dental problems and oral disease and enhance their quality of life.

Fatigue Failure Load of Molars with Thin-Walled Prosthetic Crowns Made of Various Materials: A 3D-FEA Theoretical Study.

PURPOSE: The aim of the study was to compare the fatigue lifetime of thin-walled molar crowns made of all-ceramic CAD/CAM materials under three different cyclic load conditions. METHODS: The crowns were fatigued using a range of forces similar to which crowns in the molar region might be subjected. Crowns of two thin-walled thicknesses (0.7 mm and 1.1 mm) were prepared from Zirconia and lithium disilicate. Numerical methodologies to simulate the behavior of a restored tooth were applied to evaluate the fatigue lifetimes under multiple cyclic loading; 50 N, 100 N, 150 N. An 8 mm hemispherical indenter was used to simulate the mechanical stress of opposing teeth during mastication, and applied the fatigue load at the center of the crowns. RESULTS: The results show that the predicted survival rates for 0.7 mm and 1.1 mm Zirconia crowns were not significantly different. The number of life cycles predicted for Zirconia under all fatigue loads indicates that these crowns can live longer than five clinical years (when crowns are in service). However, crowns made from lithium disilicate also can be predicted to survive longer than five clinical years (under load up to 100 N). Crowns made of lithium disilicate should have 1.1 mm thickness to survive longer than five clinical years (when crowns are in service). CONCLUSION: Zirconia crowns exhibit significantly higher fracture resistance compared with lithium disilicate crowns, making them better suited to handle higher masticatory loads encountered in the posterior region of the mouth. Lithium disilicate can survive more than five clinical years (when their thickness is 1.1 mm).

A Scoping Review on the Accuracy of Fit of Removable Partial Dentures in a Developing Digital Context.

PURPOSE: The aim of this paper is to evaluate studies on the quality of fit of alloy removable-partial-dentures (RPDs) produced by computer-aided design/computer-aided manufacturing (CAD/CAM) and rapid prototyping (RP) technology. This paper offers a comprehensive scoping review of various methods of assessing the quality of fit of RPDs in the context of a developing digital approach to manufacturing and assessment. METHODOLOGY/APPROACH: A search was made using MEDLINE/PubMed, Scopus, and Science Direct to identify the studies of the accuracy of fit of RPDs. FINDINGS: Optical and physical examination of dentures "in situ" on the model or in the patient's oral cavity were the most commonly used methods for the assessment of fit of RPDs. Eighteen of the included studies assessed the internal fit between RPDs and oral tissues or models using either polyvinyl silicone materials as filler, calipers, photographs, and microscopes or a combination of these. Two studies used visual assessment. Most studies reported that the fit of RPDs ranged from satisfactory to excellent. However, many of these assessments seemed somewhat subjective and flawed with regard to assessing indentations of the framework into a model or distortion. Two papers used a new method of computer-based superimposition which included a color map of discrepancies to assess the fit of the machine-produced RPDs offering possibilities to quantify the assessment of fit, perhaps leading to a more objective assessment. Despite the limited number of clinical trials, the available evidence was thought to reinforce the claim that the fit of RPDs fabricated digitally was acceptable. CONCLUSION: The recent introduction of color maps to compare the differences between the fitting surface and the model is promising. However, a new method for displaying discrepancies shown by color maps is introduced, which could lead to a more quantitative assessment.

Disinfection of dental impressions: knowledge and practice among dental technicians.

Background: Dental impressions are a common source for transmission of infection between dental clinics and dental labs. Dental impressions can be cross-contaminated by patient's saliva and blood, which then cross-infect the dental casts poured from the impressions. Objective: To evaluate the current practices of disinfection of dental impressions and their protocols and to assess the knowledge of cross-infection control among dental technicians in Jordan. Method: Dental technicians (n=85) completed a self-administered questionnaire about their practices of disinfection for dental impressions. Results: The distribution of dental technicians was 63.8% fixed prosthodontics, 23.5% removable prosthodontics, 7.8% orthodontics, and 4.8% maxillofacial prosthodontics. The majority of the laboratories did not have instructions related to disinfection of impressions. About 50% of technicians were vaccinated against HBV. About 44.7%, and 42.9% of labs reported that they never disinfect alginate or silicon impressions, respectively. In addition, the majority of lab owners (53%) believed that the dentist should disinfect the impressions before shipping them to dental laboratories, while (45%) believed that disinfecting the impressions is the responsibility of the dental assistant. Moreover, about 38% of this study population reported not using gloves in their labs. In those labs were disinfection was used, 51% used spray disinfection whereas 32.6% used immersion disinfection. The cost of disinfectant was ranked as the most important factor (51.3% of the cases) for the dental technician to choose the disinfectant followed by its effectiveness. Conclusion: Dental technician practices in impression disinfection was not satisfactory, therefore, education programs about impression disinfection are needed.

Fabrication of a resin appliance with alloy components using digital technology without an analog impression.

The aim of this study was to fabricate a resin appliance incorporating "wire" components without the use of an analog impression and dental casts using an intraoral scanner and computer technology to build the appliance. This unique alignment of technology offers an enormous reduction in the number of fabrication steps when compared with more traditional methods of manufacture. The prototype incorporated 2 Adams clasps and a fitted labial bow. The alloy components were built from cobalt-chromium in an initial powdered form using established digital technology methods and then inserted into a build of a resin base plate. This article reports the first known use of computer-aided design and additive manufacture to fabricate a resin and alloy appliance, and constitutes proof of the concept for such manufacturing. The original workflow described could be seen as an example for many other similar appliances, perhaps with active components. The scan data were imported into an appropriate specialized computer-aided design software, which was used in conjunction with a force feedback (haptic) interface. The appliance designs were then exported as stereolithography files and transferred to an additive manufacturing machine for fabrication. The results showed that the applied techniques may provide new manufacturing and design opportunities in orthodontics and highlights the need for intraoral-specific additive manufacture materials to be produced and tested for biocompatibility compliance. In a trial, the retainer was fitted orally and judged acceptable by the clinician according to the typical criteria when placing such appliances in situ.

Design and fabrication of a sleep apnea device using computer-aided design/additive manufacture technologies.

The aim of this study was to analyze the latest innovations in additive manufacture techniques and uniquely apply them to dentistry, to build a sleep apnea device requiring rotating hinges. Laser scanning was used to capture the three-dimensional topography of an upper and lower dental cast. The data sets were imported into an appropriate computer-aided design software environment, which was used to design a sleep apnea device. This design was then exported as a stereolithography file and transferred for three-dimensional printing by an additive manufacture machine. The results not only revealed that the novel computer-based technique presented provides new design opportunities but also highlighted limitations that must be addressed before the techniques can become clinically viable.

CAD/CAM/AM applications in the manufacture of dental appliances.

The purposes of this study were to apply the latest developments in additive manufacturing (AM) construction and to evaluate the effectiveness of these computer-aided design and computer-aided manufacturing (CAD/CAM) techniques in the production of dental appliances. In addition, a new method of incorporating wire into a single build was developed. A scanner was used to capture 3-dimensional images of Class II Division 1 dental models that were translated onto a 2-dimensional computer screen. Andresen and sleep-apnea devices were designed in 3 dimensions by using FreeForm software (version 11; Geo Magics SensAble Group, Wilmington, Mass) and a phantom arm. The design was then exported and transferred to an AM machine for building.