Faculty Bibliography

PURPOSE/OBJECTIVE:The purpose of this Best Evidence Consensus Statement was to evaluate the existing literature on the stomatognathic system's ability to adapt to occlusal changes. MATERIALS AND METHODS/METHODS:The search term stomatognathic system was not useful as it resulted in over 400,000 results nor was the search term temporomandibular joint adaptation with 738 results due to the large number of references not related to the topic. The terms stomatognathic system adaptation to occlusal changes (186 results), teeth flexion (139 results), muscle adaptation to dental occlusion (278 results), and occlusal changes and neuroplasticity (11 results) provided the best selection of articles related to the topic. Limiting the above searches to systematic reviews and randomized controlled clinical trials resulted in multiple publications that were related to the question.9-13 Other literature reviews, data-based publications, and expert opinion resources have been included due to their relationship to the question. RESULTS:From the extensive list of search results, 242 articles were determined to be potentially related to the focus question and were evaluated with 56 being included in this paper. It was determined that the stomatognathic system adapts to occlusal changes through the temporomandibular joint, muscles, teeth and bone. The dynamically modified periosteum on the articulator surfaces of the condyle and fossa has a unique load-bearing morphology with 3 subarticular layers of fibrocartilage that absorb and dissipate both peak (impact) and sustained loads. Adaptability of the TMJs and muscles can be documented through studies where artificially produced occlusal interferences were placed in patients and those study participants with normal temporomandibular joints (TMJs) adapted fairly well whereas those with a previous history of temporomandibular disorders (TMD) did not adapt as well. CONCLUSIONS:Available evidence indicates patients generally adapt to the occlusal change inherent in orthodontic treatment, mandibular advancement surgery, and the use of mandibular advancement devices. The head and neck muscles also adapt to occlusal changes in patients without a history of TMD. The dentition adapts to changes through the bone and periodontal ligaments as well as the ability of teeth to undergo slight flexion under masticatory loading. This article is protected by copyright. All rights reserved.

STATEMENT OF PROBLEM/BACKGROUND:Recent studies have shown that torque-limiting devices (TLDs) do not meet their torque targets and are affected by factors such as the use of the TLDs and the sterilization processes used. PURPOSE/OBJECTIVE:The purpose of this in vitro study was to investigate the accuracy of TLDs currently in use in the Advance Education Program in Prosthodontics at the New York University College of Dentistry. MATERIAL AND METHODS/METHODS:Five new and 46 in-use TLDs (Nobel BioCare) from the implant kits of the graduate students were evaluated. One investigator was trained and calibrated before testing and after every 10 evaluations. A 3-jaw chuck was mounted on the center of a cap testing device by using the provided mounting screws. A LOCATOR torque driver was clamped into the chuck, and a torque wrench driver was attached to it. The device was placed on a flat table with direct overhead lighting that allowed the investigator to have a consistent view of the notches on the TLDs. A piece of cardboard was attached to the device to ensure that the investigator could not see the readouts. The blinded researcher inserted the wrench and applied the appropriate torque force at the designated notches while another researcher recorded the results. Two readings were made for each TLD at 15, 35, and 45 Ncm. A 2-way ANOVA and an intraclass correlation coefficient to test for intraclinician reliability were performed by using a statistical software program (α=.05). RESULTS:Two TLDs were damaged and not tested. The 2-way ANOVA demonstrated no significant difference (P>.05) between graduate students in year 1, 2, and 3 or between the autoclaved and new TLDs. The intraclass correlation coefficient was 0.861 for 15 Ncm, 0.589 for 35 Ncm, and 0.764 for 45 Ncm. CONCLUSIONS:In this in vitro study, new and used TLDs all met the recommended torque values. No significant differences were found among groups, suggesting that autoclaving and use did not affect the accuracy of the TLDs tested.

STATEMENT OF PROBLEM/BACKGROUND:Although numerous studies have been performed on the accuracy of intraoral scanners, determining the clinical significance of the results is problematic. PURPOSE/OBJECTIVE:The purpose of this in vitro study was to evaluate the trueness and precision of 4 intraoral optical scanners (IOSs) on a 6-implant model and provide a method to help determine clinical significance. MATERIAL AND METHODS/METHODS:A polymer mandibular edentulous model with 6 hexagonal scan bodies (Ritter) was fabricated, and a control scan was made by using an industrial laser line probe (FARO Edge HD Arm). Four IOSs (True Definition, TRIOS, CEREC Omnicam, Emerald Scanner) were used to scan the same model 5 times: the 20 standard tessellation language (STL) files were individually imported to a 3D inspection software program (Geomagic Control X) and superimposed over the computer-aided design (CAD) control scan. The tolerance was set at a limit of ±0.01 mm. RESULTS:None of the tested scanners were true even 10% of the time at the ±0.01-mm tolerance, and the Emerald scanner was true less than 5% of the time. Within scanners, results were precise, showing variations of no more than 2% over repeated scans. When a ±0.05-mm tolerance was selected, the percentage within tolerance increased dramatically. This made the performance of the scanners to appear better but obscured valuable information. The 3D color map was the best method for understanding the data. The color maps showed how much was within tolerance and, equally important, the amount and direction of out of tolerance, providing an easily understandable qualitative and quantitative image. CONCLUSIONS:No statistical or clinical differences were found among the scanners tested. The 3D map was the best method for observing the data.

The elemental composition of freshwater and saltwater samples around the South Pacific island of Upolu, Samoa has been investigated together with other indicators of water quality. Up to 69 elements from Li (3) to U (92) are measured in each sample, analyzed by Mattauch-Herzog-inductively coupled plasma-mass spectrometry (MH-ICP-MS). One hundred and seventy-six samples were collected from surface freshwater sources (24 rivers, two volcanic lakes, one dam) and from seawater sources from the surface to 30 m depth (45 inner reef, reef, and outer reef locations) around Upolu Island, including river mouths and estuaries. Principal component and hierarchical clustering correlation analyses were performed on quantile normalized log transformed elemental composition data to identify groups of samples with similar characteristics and to improve the visualization of the full spectrum of elements. Human activities, such as the use of herbicides and pesticides, may relate to observed elevated concentrations of some elements contained in chemicals known to have deleterious obesogenic effects on humans that may also cause coral reef decline. Furthermore, the salinity of some saltwater samples tested were very high, possibly due to climate variability, which may additionally harm the health and biodiversity of coral reefs.

The use of a dental facebow in diagnosis and treatment by the restorative dentist has been controversial in recent years. Digital alternatives have been proposed and hold promise for the future; however, the traditional facebow still has practicality in a modern restorative practice. The purpose of this paper is to review facebow use in clinical prosthodontic practice.

STATEMENT OF PROBLEM/BACKGROUND:Multiple definitions of centric relation (CR) have evolved over time that may have created confusion or impeded understanding. A recent attempt to achieve a singular definition by surveying the members of the Academy of Prosthodontics (AP) did not achieve majority consensus. PURPOSE/OBJECTIVE:The purpose of this study was to identify those aspects or attributes within the existing definitions of CR in which there was agreement or disagreement among the members of the AP. MATERIAL AND METHODS/METHODS:After pretesting and institutional review board approval, a second survey of the AP membership was performed using both email and postal mail survey methods of contact. The CR Attributes Survey separated and stratified the previous definitions of CR into 5 domains: spatial relationship, condylar position, articular disks, mandibular movement, and recording. Each domain attribute was evaluated by agree-uncertain-disagree assessments. Also recorded were demographics, perception of scientific evidence, and open comments. RESULTS:Of the total 146 fellows, 100 completed the survey for an overall response rate of 68.5%. The query completion rate ranged from 96% to 98%. The CR Attributes Survey revealed those components within each domain in which there was strong agreement, disagreement, or uncertainty. The survey assessment of those queries with a moderate to strong agreement were that CR is a "spatial relationship" that is (1) a clinically determined relationship of the mandible to the maxilla, (2) a repeatable position, (3) is independent of tooth contact, and (4) is a physiologic position. Relative to "disks," the condyles articulate with the thinnest avascular intermediate zone of their respective disks; however, there is a lack of sufficient evidence to determine the position of the disks and the condyles. Relative to "mandibular movement," CR is (1) a starting point for vertical, lateral, or protrusive movements, (2) is where the individual can make to and from lateral movements, and (3) is restricted to pure rotary movement about a transverse horizontal axis. Relative to "recording CR" (1) it can be determined in patients without pain or derangement of the temporomandibular joints (TMJs), (2) but may not be recordable in the presence of dysfunction of the masticatory system, or (3) due to the neuromuscular influence or proprioception from the dentition, (4) is a clinical useful repeatable reference position for mounting casts, or (5) for developing a functional treatment occlusion, (6) at an established vertical dimension, and (7) may vary slightly by recording method. CONCLUSIONS:The CR Attributes Survey revealed a majority agreement or consensus for various CR attributes that should be considered for defining the term 'centric relation.' In contrast, those CR attributes with a plurality agreement, disagreement, or uncertainty outcomes should be considered for exclusion. The evaluated weakness of these latter attributes indicates the need for further research and reassessment.

STATEMENT OF PROBLEM/BACKGROUND:Lack of an accepted definition for the ascending ramus of the mandible means no common reference point is available for clinical or research dialogue. PURPOSE/OBJECTIVE:The purpose of this review was to determine whether the ascending ramus has been defined, by using a search of published studies. MATERIAL AND METHODS/METHODS:PubMed was searched, using terms "ascending ramus" and "mandible." RESULTS:The search found no acceptable definition of the ascending ramus of the mandible. CONCLUSIONS:An acceptable definition for the ascending ramus of the mandible is lacking, and one is proposed here.