The buccal corridor as a possible morphological risk indicator for sleep disordered breathing.

OBJECTIVE: To explore a possible morphological relationship between buccal corridor, gingival display, transpalatal molar width, palatal height, and a cephalometric measurement (PV-A Line) as a risk indicator for sleep-disordered breathing. MATERIALS AND METHODS: Thirty subjects were enrolled. Full face maximum smile images and CBCT scans were taken. A Pearson correlation coefficient was used to identify any relationships between the variables. RESULTS: No correlations were identified between any of the variables investigated in this study as they relate to risk factors for sleep-disordered breathing. CONCLUSIONS: The amount of buccal corridor space in relation to a patient's smile and the amount of gingival display does not appear to be a reliable metric in identifying certain morphological risk factors for sleep-disordered breathing. CLINICAL SIGNIFICANCE: Assessing the amount of buccal corridor space in relation to a smile does not appear to be a reliable predictor of morphological risk for certain risk factors of sleep-disordered breathing. In addition, utilizing the amount of gingival display in a patient's maximum smile does not appear to relate directly to risks in sleep-disordered breathing. Other tests and discovery may be necessary to identify these types of patients.

Maxillary occlusal device designed with an anterior platform for guiding the occlusal adjustments during the delivery appointment: A dental protocol.

OBJECTIVE: To describe a technique for fabricating an additively manufactured maxillary occlusal device using a complete digital workflow. CLINICAL CONSIDERATIONS: The maxillary occlusal device design may include an anterior platform to guide the positioning of the mandible in a reproducible position for facilitating the delivery procedure. CONCLUSIONS: The described technique provides a more efficient and less time-consuming method for designing and manufacturing a printed occlusal device, when compared with conventional fabrication techniques. CLINICAL SIGNIFICANCE: The additively manufactured occlusal device designed with an anterior platform guides the positioning of the mandible in a reproducible position, facilitates the delivery procedures, and produces a more efficient and less time-consuming method when compared with conventional methods.

A guide for maximizing the accuracy of intraoral digital scans: Part 2-Patient factors.

OBJECTIVES: To describe the factors related to patient intraoral conditions that impact the scanning accuracy of intraoral scanners (IOSs). A new classification for these influencing factors is proposed to facilitate dental professionals' decision-making and maximize the accuracy and reliability of intraoral digital scans. OVERVIEW: Variables related to intraoral conditions of the patient that can influence the scanning accuracy of IOSs include tooth type, presence of interdental spaces, arch width variations, palate characteristics, wetness, existing restorations, characteristics of the surface being digitized, edentulous areas, interimplant distance, position, angulation, and depth of existing implants, and implant scan body selection. CONCLUSIONS: The knowledge and understanding of the patient's intraoral conditions that can impact the scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs. CLINICAL SIGNIFICANCE: The patient's intraoral conditions, or patient factors, can significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing patient factors to maximize the accuracy of IOSs.

A guide for maximizing the accuracy of intraoral digital scans. Part 1: Operator factors.

OBJECTIVES: To describe the factors related to the operator skills and decisions that influence the scanning accuracy of intraoral scanners (IOSs). A new classification for these factors is proposed to facilitate dental professionals' decision making when using IOSs and maximize the accuracy and reliability of intraoral digital scans. OVERVIEW: Each IOS system is limited by the hardware and software characteristics of the selected device. The operator decisions that can influence the accuracy of IOSs include the scanning technology and system selection, scanning head size, calibration, scanning distance, exposure of the IOS to ambient temperature changes, ambient humidity, ambient lighting conditions, operator experience, scanning pattern, extension of the scan, cutting off, rescanning, and overlapping procedures. CONCLUSIONS: The knowledge and understanding of the operator factors that impact scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs and for successfully integrating IOSs in daily practices. CLINICAL SIGNIFICANCE: Operator skills and clinical decisions significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing operator factors for maximizing the accuracy of IOSs.

An overview of the digital occlusion technologies: Intraoral scanners, jaw tracking systems, and computerized occlusal analysis devices.

OBJECTIVES: Within the development of digital technologies, dental professionals aim to integrate virtual diagnostic articulated casts obtained by using intraoral scanners (IOSs), the mandibular motion of the patient recorded by using an optical jaw tracking system, and the information provided by computerized occlusal analysis systems. This article describes the various digital technologies available for obtaining the digital occlusion of a patient and outlines its challenges and limitations. OVERVIEW: The factors that influence the accuracy of the maxillomandibular relationship of diagnostic casts obtained by using IOSs are reviewed, as well as the occurrence of occlusal collisions or mesh interpenetrations. Different jaw tracking systems with varying digital technologies including ultrasonic systems, photometric devices, and artificial intelligence algorithms are reviewed. Computerized occlusal analysis systems for detecting occlusal contacts in a time sequential manner with the pressure distribution on the occlusal surfaces are reviewed. CONCLUSIONS: Digital technologies provide powerful diagnostic and design tools for prosthodontic care. However, the accuracy of these digital technologies for acquiring and analyzing the static and dynamic occlusion need to be further analyzed. CLINICAL SIGNIFICANCE: Efficiently implementing digital technologies into dental practice requires an understanding of the limitations and state of current development of the digital acquisition methods for digitizing the static and dynamic occlusion of a patient by using IOSs, digital jaw trackers, and computerized occlusal analysis devices.

Utilizing an additively manufactured Kois deprogrammer to record centric relation: A simplified workflow and delivery technique.

A technique for fabricating an additively manufactured Kois deprogrammer is described from the initial patient data collection with an intraoral scanner to the 3D printing methods to fabricate the device. The incorporation of digital technologies for manufacturing a Kois deprogrammer provides new clinical and manufacturing tools, providing more efficient and less time-consuming design and manufacturing techniques than conventional techniques while maintaining conventional prosthodontic concepts.

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position.

Although the evolution of digital technology continues to improve patient data acquisition, the ability to both standardize the recording of the maxillary occlusal plane and capture the necessary dynamic data for dento-facial analysis remains elusive. This article describes step-by-step techniques to position the maxilla on an articulator using the natural head position and a facial reference system (Kois Facial Reference Glasses) for both analog and digital workflows. A photographic technique will be presented that captures the natural head position and allows the clinician to align a 2D reference photograph with the maxillary intraoral digital scan and the virtual articulator. Using this reference photograph, the clinician can record and communicate to the technician the maxillary arch position in relationship with the facial references, as well as transfer the additively manufactured casts in the same facial orientation for mounting and analysis either virtually or on an analog articulator.

Evaluation of fracture resistance and failure risks of posterior partial coverage restorations.

STATEMENT OF PROBLEM: Interest in posterior partial coverage restorations has increased because these restorations provide a more conservative treatment option than traditional cohesively based restorations; however, material selection has been a controversial topic in the current literature. PURPOSE: To evaluate the fracture resistance of posterior partial coverage restorations restored with different materials, examine their stress distribution, and calculate failure risks using three-dimensional (3D) finite element analysis. METHODS: Sixty extracted third molar teeth received 2-mm occlusal reduction maintaining cusp steepness of 45 degrees relative to occlusal surface. Teeth were allocated into four groups (N = 15) and restored with different materials: feldspathic ceramic, leucite-reinforced ceramic, lithium disilicate-reinforced ceramic (EMX), or indirect resin-based composite (COM). Restorations were luted with resin cement and submitted to compressive loads (Instron Corp, Norwood, MA, USA). The data were analyzed with one-way analysis of variance, followed by Tukey's HSD tests. A 3D finite element model of posterior partial coverage restorations was developed and validated. The model was used to approximate the maximum principal stress in each of the materials under a 100-N static vertical compression at the occlusal surface of the tooth. The risk of restoration failure was quantified and compared among the four different materials. RESULTS: Group EMX had fracture resistance significantly higher than other testing groups. Group COM presented the most extensive fractures involving tooth and root structures. When compared with the other materials, group EMX exhibited higher stress concentration; however, the failure risk of the restoration was lower. CONCLUSIONS: Fracture resistance and failure risks of posterior partial coverage restorations are significantly influenced by material selection. CLINICAL SIGNIFICANCE: Many restorative materials have been advocated for partial coverage restorations. It is essential to ensure that restorative materials have sufficient strength to support occlusal forces and, in case of fracture, the remaining tooth structure is not compromised or placed at risk. This study revealed that all-ceramic materials had high incidences of fractures involving the materials themselves, whereas the predominant failure of resin-based composite involved the tooth structure in a catastrophic manner.

Occlusal errors generated at the maxillary incisal edge position related to discrepancies in the arbitrary horizontal axis location and to the thickness of the interocclusal record.

STATEMENT OF PROBLEM: Determining the arbitrary transverse horizontal axis by using anatomic landmarks is a simpler clinical procedure than locating the kinematic transverse horizontal axis; however, accuracy may vary depending on individual patient anatomy. PURPOSE: The purpose of this study was to investigate an arbitrary transverse horizontal axis relative to the maxillary incisal edge and to examine the magnitude of occlusal error produced when this arbitrary transverse horizontal axis is used to mount casts in an articulator. MATERIAL AND METHODS: Seventy-three adults (43 men, 30 women) participated in this study. The distance of the arbitrary transverse horizontal axis to the maxillary central incisal edge was measured for each participant. A parametric linear regression was used to analyze the effect of sex on the distance of the arbitrary transverse horizontal axis to the maxillary central incisal edge by using statistical software (SPSS v19.0; SPSS Inc). A linear correlation analysis was used to compare the distance from the arbitrary transverse horizontal axis to the maxillary central incisal edge with the participant's height (α=.05). Four distances from the arbitrary transverse horizontal axis to the maxillary central incisal edge (80, 90, 110, 120 mm) and 3 interocclusal record thicknesses (1, 2, 3 mm) were mathematically calculated to examine the magnitude of occlusal error at the central incisor contact. RESULTS: The mean distance from an arbitrary transverse horizontal axis to the maxillary central incisal edge position was 100.12 (SD 5.33) mm for all participants. Overall, 89.04% of the participants fell within 5 mm of the 100-mm distance. No significant differences in the distance of the arbitrary transverse horizontal axis to the maxillary central incisal edge position were identified between men and women or with the participant's height. The magnitude of occlusal error at the central incisor contact ranged from 0.45 to 11.26 µm. CONCLUSIONS: The distance from an arbitrary transverse horizontal axis to the maxillary central incisal edge position was not influenced by the sex or height of the participants investigated. Variations in the distance from an arbitrary transverse horizontal axis to the maxillary central incisal edge resulted in minor occlusal discrepancies at the central incisor contact.

Comparison of load-fatigue performance of posterior ceramic onlay restorations under different preparation designs.

OBJECTIVE: The objective of this study was to evaluate the load-fatigue performance of posterior ceramic onlay restorations relative to two variables: preparation design (with or without buccal veneers); and the existing amount of tooth structure (non-worn tooth, worn tooth). METHODS: Sixty extracted third molars were divided into five groups. One group received a mesial-occlusal-distal (MOD) gold onlay restoration (control). The other four experimental groups were prepared for ceramic onlay restorations. Two of the groups additionally received 2-mm occlusal reduction to simulate occlusal wear. All restored teeth were subjected to thermocycling prior to fatigue testing. A fatigue load of 150 N was applied on the occlusal surface at a frequency of 1.2 hz, at an angle of 135 degrees to the long axis of the tooth. Specimen failure was defined as the occurrence of crack propagation in the luting cement layer. This was monitored by the strain gauge on the specimen. RESULTS: All specimens restored on worn tooth had significantly lower fatigue failure cycle counts than those of non-worn tooth. The fracture mode analysis revealed that ceramic fracture tended to be demonstrated only in the group of worn tooth groups. CONCLUSIONS: The addition of a buccal veneer component had no significant effect on the load-fatigue performance of posterior ceramic onlay restorations, but the existing amount of tooth structure did have a significant effect on the load-fatigue performance of posterior ceramic onlay restorations. Catastrophic failures (ceramic fracture) occurred only in the group of worn tooth.

Comprehensive Risk-Based Diagnostically Driven Treatment Planning: Developing Sequentially Generated Treatment.

The clinical example presented in this article demonstrates a risk-based, diagnostically driven treatment planning approach by focusing on 4 key categories: periodontal, biomechanical, functional, dentofacial. In addition, our unique approach allowed the comprehensive clinical management of a patient with complex restorative needs. A full-mouth rehabilitation was completed sequentially without sacrificing the amount of dentistry necessary to restore health, comfort, function, and esthetics. The result exceeded the patient's expectation and was made financially possible by extending treatment over numerous years.

Esthetic templates for complex restorative cases: rationale and management.

UNLABELLED: Complex restorative cases require difficult clinical decisions regarding the final esthetic outcome in which the operator must visualize the definitive restorative position of the teeth. These critical decisions need to be made before treatment is rendered. Communicating these decisions to the patient and the treatment team are crucial prior to achieving clinical success. The esthetic template is the conduit for providing excellent communication. The selection of the appropriate esthetic template is based on four sequential decisions: (1) dentofacial analysis, (2) blueprint development, (3) matrix management, and (4) template application. When utilizing an esthetic template, the clinician must know where the teeth should be placed based on a dentofacial analysis. The dentofacial analysis must then be communicated to the laboratory, and then a blueprint is developed from the diagnostic casts. A matrix is then fabricated from the blueprint and then related back to the existing dentition. The esthetic template is an invaluable communicator that can be utilized in office, with the patient at home, or even within the multidisciplinary treatment team. Clearly, the effective use of esthetic templates demonstrates a reversible way to visualize difficult esthetic decisions before any irreversible procedures are completed. Esthetic templates are a physical means of communication that provide the patient, technician, and multidisciplinary team an instrument to predictably manage complex restorative cases. The purpose of this article is to present a rationale for esthetic template selection and management of several techniques for complex restorative cases. CLINICAL SIGNIFICANCE: Complex restorative cases require difficult clinical decisions regarding the final esthetic outcome in which the operator must visualize the definitive restorative position of the teeth. The use of an esthetic template commensurate with a rationale for selection enables the operator, patient, and entire interdisciplinary team to visualize the final esthetic outcome.