The face bow is irrelevant for making prostheses and planning orthognathic surgery

Temporomandibular Disorders: Implications in Restorative Dentistry and Orthodontics

Over the past several decades, the science of restorative/reconstructive dentistry and orthodontics has evolved tremendously, following sound principles passed down from robust literature and scientific rationale. These principles have been solid and instrumental in enhancing dentistry, from a single tooth restoration to complex full-mouth rehabilitations. However, it must be noted that some of the principles and philosophies followed over these decades have been questioned based on the advances in science, technology, and evidence-based medicine. The scenario became complex when clinicians were faced with the question of guidance for optimum joint and muscle health as related to restorative dentistry and orthodontics.

Occlusal contact and clearance of posterior implant-supported single crowns designed by two different methods: a self-controlled study

BACKGROUND

Precise occlusal design of implant-supported fixed prostheses is difficult to achieve by the conventional wax-up method, often requiring chairside adjustments. The computer-aided design (CAD) method is promising. This study aims to compare the occlusal contacts and clearance of posterior implant-supported single crowns designed by the CAD and conventional methods.

METHODS

Sample size calculation indicated fourteen samples per group. Two sets of type-IV plaster casts with a single implant analog inserted in the posterior teeth region were mounted as master casts in a mechanical articulator in maximal intercuspal position (MIP). Seven working cast sets were obtained from each master cast by a closed tray technique, and mounted in MIP. Two implant-supported single crowns were designed with an occlusal clearance to achieve light occlusal contact in each working cast set by CAD and conventional method, separately. For the CAD group, the crown was designed in digital models obtained by scanning the working casts. For the conventional group, wax-up of the crown was prepared on the working casts and scanned to generate a STL file. In the working and master casts, mean and minimum occlusal clearances in the designed occlusal contact area of the both finished prostheses were calculated using the occlusal clearance (OC) and occlusal record (OR) method. The prostheses' occlusion was evaluated in master casts.

RESULTS

For the evaluation in the working casts, both design methods had similar mean occlusal clearances by the OC method (195.4 ± 43.8 vs. 179.8 ± 41.8 μm; P = 0.300), while CAD group resulted in a significantly larger minimum occlusal clearance in the designed occlusal contact area (139.5 ± 52.3 vs. 99.8 ± 43.8 μm; P = 0.043). Both design methods had similar mean and minimum occlusal clearances by the OR method (P > 0.05). For the evaluation in the master casts, both design techniques had similar mean and minimum occlusal clearances, number and distribution of occlusal contacts, and lateral interference ratios (P > 0.05).

CONCLUSION

Occlusal contact and clearance of posterior implant-supported single crowns designed by the CAD method can be at least as good as those designed by the conventional wax-up method.

Determining the occlusal plane: a literature review

Objective: The purpose of the present review was to demonstrate the utility of articulator systems and link instrumentation in determining the occlusal plane. The impact of the natural head position and anatomical landmarks on the occlusal plane location has been reported in the literature. Properly chosen instrumentation and management methods eliminate errors in determining the occlusal plane.Methods: The PubMed and the Dentistry & Oral Sciences Source (through EbscoHost) databases were searched for ways to minimize the occurrence of errors when registering and determining the occlusal plane location, with or without the use of face-bows. A hand search and citation mining supplemented the results.Results: Overall, 11 original approaches to occlusal plane determination were identified.Discussion: Identified methods of occlusal plane transfer are based on real or virtual solutions. Owing to the large variety of devices, additional comparative studies are needed.

Does the facebow affect the outcome of CAD/CAM occlusal splint. Randomized clinical trial

Background

Occlusal appliances can distribute aggressive loads which are generated by bruxism and can reduce their frequency. The facebow record, when used in the construction of occlusal appliances, helps in minimizing occlusal discrepancies. This study aimed to compare the effect of CAD/CAM stabilization occlusal splint made with and without facebow for management of bruxer patients.

Method

24 Patients who were diagnosed as bruxers were randomly assigned into two equal groups and obtained maxillary CAD/CAM occlusal stabilizing splint recorded with centric relation either with or without using a facebow. The patient satisfaction using the visual analog scale (VAS) was recorded at baseline, one month and three months’ follow-up periods. The adjustment time of both splints, from the start of splint delivery until becoming well-fitted and occlusally adjusted, was calculated using a stopwatch.

Results

The CAD/CAM occlusal splints with or without the use of facebow improved the patient's satisfaction with no statistically significant difference between both groups at baseline, one month and three months with p values of 0.73, 0.24 and 0.45 respectively. The comparison between the two modalities regarding the adjustment time showed no statistically significant difference between both groups (P = 0.06).

Conclusion

According to the results of this study; no difference was detected in patient satisfaction and the time required for adjustment of CAD/CAM occlus.

The Effect of Residual Dentition on the Dynamic Adjustment of Wear Facet Morphology on a Mandibular First Molar Crown

PURPOSE

To evaluate the effect of different residual dentitions on the dynamic adjustment of wear facet morphology on a single mandibular first molar crown with a virtual articulator.

MATERIALS AND METHODS

Gypsum casts (N = 12) of natural full dentitions were mounted on an articulator and scanned. The mandibular right first molar (#46) was prepared and a copy of the tooth before it was prepared and used to design the crown. The wear facets on the original #46 were selected and elevated by 0.3 mm in the occlusal direction to generate high points. The #46 with high points was segmented to create a digital wax pattern. Then different teeth were virtually removed to generate 4 types of residual dentitions: Type I (no teeth), Type II (adjacent teeth), Type III (ipsilateral posterior teeth and canine), and Type IV (all teeth). The crowns were adjusted dynamically with different residual teeth to guide mandibular movement of the virtual articulator. Three-dimensional deviations, negative and positive volumes between crowns and wear facets on the original #46 were analyzed. The Kruskal-Wallis test was used to analyze the results.

RESULTS

The mean deviation values and positive volumes decreased with the decrease in residual teeth, and the negative volumes showed an opposite trend. The mean deviation values, root mean square, and positive volumes were not significantly different. The negative volume of the crowns of Type I was different from that of Type IV (p = 0.031).

CONCLUSIONS

Residual dentition affects the dynamic adjustment of wear facet morphology. When there are insufficient residual teeth, mandibular movements should be accurately measured.

A Comprehensive Systematic Review In Search Of Evidence for Pragmatic Altercations in Simplified Denture

Aim:

To explore the evidence available to evaluate if simplified dentures could be as effective as the conventional complete dentures.

Materials and Methods:

A total of 1,482 articles were obtained using keywords in a Boolean search operator in the PubMed search engine, Google Scholar and Cochrane Library. Duplicates were removed and the remaining articles were subjected to a title analysis which yielded a total of 20. Further analysis of the article abstracts led to an exclusion of four articles. The remaining 16 articles were subjected to full text analysis which finally yielded a total of 11 articles.

Results:

The cumulative results of the meta-analysis for oral health-related quality of life, patient satisfaction and professional quality of denture show no significant difference ( P > .05) between conventional and simplified dentures.

Conclusion:

Based on the available evidence adjusted for the potential literature/geographic bias, we conclude that the conventional procedures in complete denture fabrication such as facebow and gothic arch tracing do not improve the quality of the denture outcome from patients’ perspective and simplified dentures are equally effective as conventional complete dentures.

The evolution of temporomandibular disorders: A shift from experience to evidence

After over 80 years of much obsession as well as avoidance of the subject of temporomandibular disorders (TMDs), the dental profession is still divided over what they are and how to deal with them. Over this period, nearly every discipline in dentistry has played some role in the development of this field. Unfortunately, a significant amount of this information has been based on personal opinion, experience-based philosophies, or poorly conducted research. Furthermore, each dental specialty has been responsible for contributing to the concepts of the etiology and management of TMDs with their own professional bias; for example, orthodontists describe these problems in orthodontic terms and offer orthodontic treatments or solutions for their patients. As various treatment approaches were found to be effective at least some of the time, this has further led to misinformation and confusion within the profession. Advances in research from diverse fields, including neurophysiology, pain pathophysiology, genetics, endocrinology, behavioral sciences, and psychology, have significantly altered our understanding of TMDs and how they should be managed. The rigid mechanical and dental-based model of the past has been gradually replaced by a biopsychosocial medical model for the diagnosis and treatment of TMDs as well as other acute and chronic pain disorders. This paper discusses the evolution of our understanding of TMDs since they were first described 85 years ago. Contemporary scientific findings and their implications are presented in some detail for clinicians who wish to provide the appropriate management for their orofacial pain patients.

Mounting casts on a mechanical articulator by using digital multisource data: A dental technique

A facebow transfer is typically used for mounting a maxillary gypsum cast in an ideal location in a mechanical articulator. However, the facebow transfer procedure is difficult and may cause the patient discomfort. This proposed technique uses a patient's cone beam computed tomography (CBCT) data to reproduce the occlusal plane in relation to digital articulator scan data, align the patient's gypsum cast or intraoral scan data on the reproduced plane, and then transfer the data to a mechanical articulator.

The accuracy and stability of the maxillary position after orthognathic surgery using a novel computer-aided surgical simulation system

Background

Many reports have been published on orthognathic surgery (OGS) using computer-aided surgical simulation (CASS). The purpose of this study was to evaluate the accuracy of the maxillary repositioning and the stability of the maxilla in patients who underwent OGS using a newly developed CASS program, a customized osteotomy guide, and a customized miniplate.

Methods

Thirteen patients who underwent OGS from 2015 to 2017 were included. All patients underwent a bimaxillary operation. First, a skull-dentition hybrid 3D image was rendered by merging the cone beam computed tomography (CBCT) images with the dentition scan file. After virtual surgery (VS) using the FaceGide® program, patient-customized osteotomy guides and miniplates were then fabricated and used in the actual operation. To compare the VS with the actual surgery and postoperative skeletal changes, each reference point marked on the image was compared before the operation (T0) and three days (T1), four months (T2), and a year (T3) after the operation, and with the VS (Tv). The differences between ΔTv (Tv-T0) and ΔT1 (T1-T0) were statistically compared using tooth-based reference points. The superimposed images of Tv and T1 were also investigated at eight bone-based reference points. The differences between the reference points of the bone surface were examined to evaluate the stability of the miniplate on the maxilla over time.

Results

None of the patients experienced complications. There were no significant differences between the reference points based on the cusp tip between ΔTv and ΔT1 (p > 0.01). Additionally, there were no significant differences between the Tv and T1 values of the bone surface (p > 0.01). The mean difference in the bone surface between Tv and T1 was 1.01 ± 0.3 mm. Regarding the stability of the miniplate, there were no significant differences between the groups. The difference in the bone surface between T1 and T3 was − 0.37 ± 0.29 mm.

Conclusions

VS was performed using the FaceGide® program, and customized materials produced based on the VS were applied in actual OGS. The maxilla was repositioned in almost the same manner as in the VSP plan, and the maxillary position remained stable for a year.