Lean Methods Applied to CAD/CAM Pedagogy in the Dental Simulation Laboratory.

Dental education is incorporating computer-assisted design/computer-assisted manufacturing (CAD/CAM) into patient care delivery. The aim of this study was to determine if lean production methods applied to the preclinical phase of dental education would reduce the students' time (efficiency) to complete CAD/CAM indirect restorations (CAD/CAM IR) without compromising the desired quality of the CAD/CAM tooth preparations (effectiveness). In 2016, all third-year students at one U.S. dental school were randomly assigned to control and research groups (approximately 33 per group). The control group was taught using existing methods, while the course was redesigned to incorporate lean methods for the research group. Cycle times of the CAD/CAM IR process for both groups were collected and statistically analyzed to compare the effectiveness of the redesign. Standardized grading forms and tools were used to assess the quality of the CAD/CAM tooth preparations. The research group demonstrated significantly faster preparation times with both crowns and onlays (p<0.05) than the control group. The research group also produced CAD/CAM crown and onlay designs at a significantly faster pace than the control group (p<0.05). There was no significant difference between the control and research groups associated with the scanning process times (p>0.05) nor in the quality of the CAD/CAM tooth preparations (p>0.05). This study demonstrated that lean methods applied to pedagogy significantly decreased preparation and design times in a CAD/CAM restorative dentistry course without compromising the quality of the CAD/CAM tooth preparations.

Comparison of cutting efficiency with different diamond burs and water flow rates in cutting lithium disilicate glass ceramic.

BACKGROUND: This study compared different diamond burs and different water flow rates on the cutting efficiency of sectioning through lithium disilicate glass ceramic. METHODS: The authors used a standardized cutting regimen with 4 brands of diamond burs to section through lithium disilicate glass ceramic blocks. Twelve diamonds of each brand cut through the blocks in randomized order. In the first part of the study, the authors recorded sectioning rates in millimeters per minute for each diamond bur as a measure of cutting efficiency. In the second part of the study, the authors compared sectioning rates using only 1 brand of diamond bur, with 3 different water flow rates. RESULTS: The authors averaged and compared cutting rates of each brand of diamond bur and the cutting rates for each flow rate using an analysis of variance and determined the differences with a Tukey honest significant difference test. One diamond bur cut significantly slower than the other 3, and one diamond bur cut significantly faster than 2 of the others. The diamond bur cutting efficiency through lithium disilicate glass ceramic with a 20 mL/min water flow rate was significantly higher than 15 mL/min. CONCLUSIONS: There are differences in cutting efficiency between diamond burs when sectioning lithium disilicate glass ceramic. Use a minimum of 20 mL/min of water coolant flow when sectioning lithium disilicate glass ceramic with dental diamond burs to maximize cutting efficiency. PRACTICAL IMPLICATIONS: Recommendations for specific diamond burs with a coarse grit and water flow rate of 20 mL/min can be made when removing or adjusting restorations made from lithium disilicate glass ceramic.

Simplified Technique for Incorporating a Metal Mesh into Record Bases for Mandibular Implant Overdentures.

Mandibular implant-retained overdentures have become the standard of care for patients with mandibular complete edentulism. As part of the treatment, the mandibular implant-retained overdenture may require a metal mesh framework to be incorporated to strengthen the denture and avoid fracture of the prosthesis. Integrating the metal mesh framework as part of the acrylic record base and wax occlusion rim before the jaw relation procedure will avoid the distortion of the record base and will minimize the chances of processing errors. A simplified method to incorporate the mesh into the record base and occlusion rim is presented in this technique article.

Unique CAD/CAM three-quarter crown restoration of a central incisor: a case report.

Computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry has been in use for more than 2 decades. Recent improvements in this technology have made CAD/CAM restorations a viable alternative for routine dental care. This technology is being taught in dental schools to prepare students for contemporary dental practice and is particularly useful in unique restorative situations that allow conservation of tooth structure. This case report describes the restoration of a central incisor that was previously restored with an unesthetic three-quarter gold crown. The tooth exhibited recurrent caries and an unaffected labial wall of supported enamel. A CAD/CAM three-quarter crown was planned to conserve tooth structure. After preparation, the tooth was scanned for a CAD/CAM crown in order to fabricate a ceramic restoration, which was then milled and bonded, producing an esthetic result. Typically, in cases of esthetic enhancement, a labial laminate restoration is fabricated, but in this situation, a different approach was necessary to make a design for the lingual surface of an anterior tooth.

The occlusal guard: a simplified technique for fabrication and equilibration.

Hard occlusal guards have been used effectively to treat myofacial pain originating from parafunctional activities. Also, they can protect the natural dentition when it opposes porcelain restorations, help to evaluate changes in occlusal vertical dimension during full mouth rehabilitation, minimize further tooth loss in patients with abfraction lesions, and redirect occlusal loads more favorably onto dental implant-supported prostheses. A simplified technique is described to fabricate a properly designed wax model of an occlusal guard that can be processed in acrylic in the same manner used to construct a complete denture.

The acrylic resin transfer coping technique for making accurate interocclusal records.

When the goal of restorative treatment is to maintain the patient's preexisting intercuspation and occlusal vertical dimension (OVD) following tooth preparation for crowns or fixed partial dentures (FPDs), casts must be mounted on an articulator in the same pretreatment tooth-to-tooth relationship. A simple technique is described that uses acrylic transfer copings over prepared teeth to record and preserve this relationship so that working and opposing casts can be mounted accurately. The technique may be used to recapture the lost third leg of the tripod after teeth have been prepared. To further reduce errors when mounting casts onto an articulator, a method is recommended that uses rigid connectors to join and stabilize casts in a manner that minimizes potential movement during placement and setting expansion of gypsum mounting materials.

A resin acrylic and plaster solder index technique for realigning an ill-fitting fixed partial denture framework.

A resin acrylic and plaster solder index technique is a simple, accurate, secure, and cost-effective way to intraorally realign an ill-fitting fixed partial denture framework. Once the fixed partial denture framework is sectioned and segments are found to fit, an intraoral index preserves the correct relationship among segments and holds castings together securely enough to avoid separating until they can be embedded in solder investment and soldered in the dental laboratory. This technique is described here, together with a literature review and a discussion of the technique's advantages relative to other indexing techniques and materials.

Thermal safety of Er:YAG and Er,Cr:YSGG lasers in hard tissue removal.

OBJECTIVE: The aim of this study was to compare the thermal safety of Er:YAG and Er,Cr:YSGG lasers with conventional multi-use and single-use diamond burs. BACKGROUND DATA: Thermal effect of tooth preparation is mostly evaluated through the pulp chamber because it is difficult to measure the temperature of the preparation surface. A new in vitro method was introduced to simultaneously evaluate the heat increase of the preparation surface together with the pulp chamber. METHODS: Six laser and bur instrument groups were used to make standardized preparations on buccal surfaces of 60 intact third molars. The preparations removed an equal volume of hard tissue from each tooth (4 mm occluso-gingival x 8 mm mesial-distal x 1.6 mm bucco-lingual). The teeth also included tunnel preparations from the opposite (lingual) surface, exposing the pulpal axial wall (axial dentin wall in contact with the pulp chamber from the preparation surface site). An infrared thermal camera was positioned to capture the preparation surface in direct vision, while the pulpal axial wall was indirectly reflected to the thermal camera via a minimal-energy-loss mirror. Data from both surfaces were analyzed statistically using Nested Least Squares Analysis. RESULTS: The laser groups generated significantly lower heat compared to bur groups on the preparation surfaces. In contrast, both lasers generated greater pulpal heat increase, and the Er:YAG laser group showed significance (p < 0.0001). CONCLUSIONS: Lasers produced less heat on the preparation surface but more on the pulpal axial wall. However the temperature rise was less than the 5.5 degrees C threshold margin of safety.

Strategic partnerships between academic dental institutions and communities: addressing disparities in oral health care.

BACKGROUND: A landmark report from the U.S. surgeon general identified disparities in oral health care as an urgent and high-priority problem. A parallel development in the dental education community is the growing consensus that significant curriculum reform is long overdue. METHODS: The authors performed a literature review and conducted a series of structured interviews with key institutional and community stakeholders from seven geographical regions of the United States. They investigated a wide range of partnerships between community-based dental clinics and academic dental institutions. RESULTS: On the basis of their interviews and literature review, the authors identified common themes and made recommendations to the dental community to improve access to care while enhancing the dental curriculum. CONCLUSIONS: Reducing disparities in access to oral health care and the need for reform of the dental curriculum may be addressed, in part, by a common solution: strategic partnerships between academic dental institutions and communities. Practice Implications. Organized dentistry and individual practitioners, along with other major stakeholders, can play a significant role in supporting reform of the dental curriculum and improving access to care.

The effect of handpiece spray patterns on cutting efficiency.

BACKGROUND: High-speed handpieces' spray ports direct coolant at the cutting interface. The authors evaluated the effect of the number of ports and their positions on cutting rates, or CRs. METHODS: The authors performed cutting studies on a machinable ceramic block using an established testing regimen. One-port, three-port and four-port handpieces from one manufacturer were operated at maximum torque and rotation speed under a water flow of 25 milliliters per minute. The authors made 6-millimeter long edge and groove cuts in 13-mm cross-section blocks using six medium-grit diamond burs for each handpiece. Each bur cut a total of 78 mm. The authors determined CR as the time to transect the block and analyzed the data by two-way analysis of variance with post hoc Scheffé tests. RESULTS: CRs varied by the type of cut and the number of spray ports. No differences were found in CRs for the three handpieces during edge cutting. The one-port handpiece cut significantly slower (P < .001) than did the three- and four-port handpieces during groove cutting. CONCLUSION: The data indicate that the number of handpiece spray ports, and their positioning relative to the bur affect water supply to the cutting interface and, consequently, the CR under these study conditions. CLINICAL IMPLICATIONS: Optimal cutting efficiency requires good coolant access, especially within restricted areas. A multiple-port handpiece may be advantageous when preparing the interproximal region for a crown or a proximal box, owing to the better water spray pattern. Dentists should consider the influence of the number of spray ports when selecting handpieces for cutting procedures.