Occlusion for fixed prosthodontics: a historical perspective of the gnathological influence

Virtual occlusal records acquired by using intraoral scanners: A review of factors that influence maxillo-mandibular relationship accuracy

PURPOSE

This review aims to provide a comprehensive summary of how much progress has been made in the field of virtual occlusal records (VOR) obtained with intraoral scanners (IOSs), their accuracy, and what factors influence their accuracy.

MATERIALS AND METHODS

An electronic search was performed in MEDLINE via PubMed and Scopus databases in February 2023. Eligible articles were clinical or in vitro studies evaluating the accuracy of virtual occlusal records with intraoral scanners in completely dentate and partially edentulous arches.

RESULTS

Virtual occlusal records have shown promising results in terms of accuracy, with some studies reporting a high level of agreement with traditional methods. Key factors influencing the accuracy of VOR through intraoral scanners were identified which encompass multiple parameters such as scanner brands, imaging technology, scan quality, best-fit alignment, software algorithms, intermesh penetrations, and the number of sections and dimensions of the virtual occlusal record. In partially edentate areas, the lack of landmarks in the edentulous area compromises the accuracy of VOR, thus limiting the use of IOS in patients with missing teeth.

CONCLUSION

Understanding and recognizing these influencing factors will increase the predictability and reliability of dental treatments completed by using digital workflows.  However, certain challenges need to be addressed which can influence its accuracy and limit its use in daily practice. Future research should focus on improving these factors to enhance the clinical applicability of virtual occlusal records.

Differences in maxillomandibular relationship recorded at centric relation when using a conventional method, four intraoral scanners, and a jaw tracking system: A clinical study

STATEMENT OF PROBLEM

Digital systems including intraoral scanners (IOSs) and optical jaw tracking systems can be used to acquire the maxillomandibular relationship at the centric relation (CR). However, the discrepancy of the maxillomandibular relationship recorded at the CR position when using digital methods remains uncertain.

PURPOSE

The purpose of this clinical study was to compare the accuracy of the maxillomandibular relationship recorded at the CR position using a conventional procedure, 4 different IOSs, and an optical jaw tracking system.

MATERIAL AND METHODS

A completely dentate volunteer was selected. A Kois deprogrammer (KD) was fabricated. Six groups were created based on the technique used to obtain diagnostic casts and record the maxillomandibular relationship at the CR position: conventional procedures (CNV group), 4 IOS groups: TRIOS4 (TRIOS4 group), iTero Element 5D (iTero group), i700 wireless (i700 group), Primescan (Primescan group), and a jaw tracking system (Modjaw) (Modjaw group) (n=10). In the CNV group, conventional diagnostic stone casts were obtained. A facebow record was used to mount the maxillary cast on an articulator (Panadent). The KD was used to obtain a CR record for mounting the mandibular cast, and the mounted casts were digitized by using a scanner (T710) to acquire the reference scans. In the TRIOS group, intraoral scans were obtained and duplicated 10 times. The KD was used to obtain a bilateral virtual occlusal record at the CR position. To acquire the specimens of the iTero, i700, and Primescan groups, the procedures in the TRIOS4 group were followed, but with the corresponding IOS. In the Modjaw group, the KD was used to record and export the maxillomandibular relationship at the CR position. Articulated virtual casts of each group were exported. Thirty-six interlandmark linear measurements were computed on both the reference and experimental scans. The distances obtained on the reference scan were used to calculate the discrepancies with the distances obtained on each experimental scan. The data were analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey tests (α=.05).

RESULTS

The trueness and precision of the maxillomandibular relationship record were significantly affected by the technique used (P<.001). The maxillomandibular relationship trueness values from high to low were iTero (0.14 ±0.09 mm), followed by the Modjaw (0.20 ±0.04 mm) and the TRIOS4 (0.22 ±0.09 mm) groups. However, the iTero, Modjaw, and TRIOS4 groups were not significantly different from each other (P>.05). The i700 group obtained the lowest trueness and precision values (0.40 ±0.22 mm) of all groups tested, followed by the Primescan grop (0.26±0.13 mm); however, the i700 and Primescan groups had significantly lower trueness and precision than only the iTero group (P<.05).

CONCLUSIONS

The trueness and precision of the maxillomandibular relationship recorded at the CR position were influenced by the different digital techniques tested.

CLINICAL AND INSTRUMENTAL STUDY RESULTS OF COMPARING DIGITAL OCCLUSION INDICES AT REGISTRATION OF INTERCUSPAL POSITION IN PATIENTS WITH EDENTULOUS SPACES BEFORE AND AFTER PROSTHETIC REHABILITATION

Aim. The research aims at carrying out a comparative clinical and instrumental analysis related to registering occlusal relations of intercuspal contact position in patients with edentulous spaces before and after prosthetic rehabilitation using various registration materials. Material and Methods. Examination of 5 patients of both genders aged 28 to 51 years was performed at clinical bases of the department of surgical and prosthetic dentistry of the Faculty of Postgraduate Education at Danylo Halytskyi Lviv National Medical University. Clinically, all patients were provided with a standard diagnostic dental examination including the control of a temporomandibular joint condition, examination of masticatory muscles, as well as the static and dynamic occlusion with the help of articulating wax and paper according to the two-stage Bausch method. The examination also involved impressions of dental arches of both jaws. Their cast models were produced for laboratory study. The received register, involving the use of materials, namely Futar D, metalized wax, and Consiflex, were reexamined for compliance with the intercuspal contact position in all patients. Location of the occlusal contact areas of antagonistic teeth was determined using Bausch Progress 100® 0.1 mm thick articulating paper (Bausch, Germany). Simultaneously, instrumental registration of digital occlusion indices was performed using the T-scan III device (Boston, USA). Results and Discussion. While comparing mean values of the percentage distribution between the left and right halves, the greatest asymmetry was recorded with the use of Futar D material in the D mode both before and after treatment. According to the results of performed instrumental study concerning occlusal relations with the help of the T-Scan III device, it was found that in case of applying Futar D registration material in patients before prosthetic rehabilitation, mean values of occlusal forces at MAX on the left were (50.72 ± 13.86)%, on the right they were (49.28±13.86)%, after prosthetic rehabilitation they made up (50.12±8.75)% on the left, and (49.88±8.75)% on the right. In case of Consiflex registration material application in patients before prosthetic rehabilitation, it was found that COF mean values at MAX on the left accounted (41.28±16.97) %, while on the right they accounted (58,72±16,97) %. After prosthetic rehabilitation - (54.72±13.39) % on the left, and (45.28±13.39) % on the right, respectively. The conducted instrumental studies demonstrate challenging opportunities for revealing personalized features of static and dynamic occlusal balance at clinical registration of intermaxillary position of intercuspation by various registration materials and methods. Conclusions. 1. A uniform contact of dental arches with synchronous contact of all tooth groups is an important feature of physiologically coordinate dentofacial system functioning. Frequent sliding contacts are observed in ending intercuspal contact position at static and dynamic occlusion. Area of the contact surfaces of the teeth expands with the increase of occlusal pressure in the direction of the maximum intercuspal contact position (maximum intercuspation). At the same time, occlusal pressure occurs in this area, causing the redistribution of functional load of the patients' dentofacial system components. Occlusal space in the intercuspal contact position and the maximum intercuspation or the D index, which can be established using the "Tekscan III" digital technology, manifests the spatiotemporal indices of inter-maxillary relations redistribution. The values of these indices in patients with partial anodontia provoke a special interest. The use of Futar D registration material at performing clinical and instrumental analysis of digital indices of the transition from intercuspal contact position to maximum intercuspation, allowed establishing the extension of occlusal joining of teeth duration after dental prosthetics by 1.02 times, reduction of the length of joining trajectory by 1.37 times. The use of Consiflex resulted in the identical length of joining trajectory and extension of the duration of occlusal joining of teeth after dental prosthetics by 1.04 times. The application of metalized wax was characterized by the identical length of joining trajectory and prolonged occlusion time after dental prosthetics by 1.61 times.

Full Mouth Rehabilitation Using the Twin Stage Procedure in a Patient with Amelogenesis Imperfecta: A Case Report

Amelogenesis imperfecta (AI) refers to a group of inherited odontological disorders that alter enamel formation. The AI variant is based on the primary enamel defect, classified as hypoplastic type I, hypo maturation type II, hypo calcification type III, and hypo maturation type IV. AI is commonly linked with the loss of the normal occlusal plane, the loss of the vertical dimension of occlusion (VDO), and impaired functions and esthetics. This case report describes the Hobo and Takayama twin-stage procedure for the rehabilitation of a patient with hypoplastic AI.

The occlusal precision of milled versus printed provisional crowns

OBJECTIVES

The aim of this study was to compare the occlusal precision of computer-aided-design/ computer-assisted-manufacturing (CAD/CAM) milled versus 3D printed polymethylmethacrylate (PMMA) temporary prosthetic crowns , starting from the same digital CAD design.

MATERIALS AND METHODS

The study sample included 34 patients presenting 34 premolars in need of prosthetic rehabilitation: a total of 68 temporary crowns were manufactured, 34 of which milled and 34 printed. Immediately after manufacturing, the milled and printed provisionals were scanned with a desktop scanner (E1, 3Shape) to obtain STL files, that were superimposed to the original CAD design in order to identify the occlusal trueness (Analysis A). A second occlusal comparison was performed by scanning both kind of provisional after being placed intraorally with Trios scanner (3 Shape); intraoral scans were obtained in order to compare STL files of provisionals before and after occlusal adjustments (Analysis B).  The occlusal trueness was identified at three reference points, P1 (vestibular cusp), P2 (palatal / lingual cusp), P3 (central fossa). The statistical analysis was performed using the R 3.4.3 statistical software (The R Foundation for Statistical Computing), with a significance level of p <0.05.

RESULTS

Overall, the printed crowns showed lower occlusal differences than the milled crowns, when compared to the CAD design file, with a statistically significant difference in P1 (difference of 0.025 ± 0.046 mm), P2 (difference of 0.027 ± 0 0.044 mm) and P3 ( difference of 0.018 ± 0.050) for Analysis A (p <0.05). In the Analysis B the direct comparison between the degree of average difference between the pre-adjustment and the post-occlusal adjustment of the milled and printed crowns shows that the printed crowns have lower occlusal mean difference values in all three points compared to the milled ones (difference of 0.146 ± 0.273 mm in P1, 0.285 ± 0.360 mm in P2 and 0.257 ± 0.277 mm in P3).

CONCLUSIONS

Within the limitation of this study, the data obtained showed a better occlusal surface dimensional accuracy of the 3D printed provisional crowns, when compared to the milled ones. Comparing the results obtained, it is possible to assume that the intraoral scans also had a contribution to occlusion, beside the manufacturing method. 3D printing can be successfully applied for manufacturing temporary PMMA crowns.

Philosophies of full mouth rehabilitation: A systematic review of clinical studies

Aim:

To systematically review the available literature on full mouth rehabilitation of the worn out dentition to help the clinician to choose a suitable philosophy to treat an individual Turner and Missirlian classification.

Settings and Design:

Systematic review following PRISMA guidelines.

Materials and Methods:

The electronic search engine explored for relevant published studies from the earliest available date, from January 1960 till October 2018. Search terms included were “full mouth rehabilitation OR occlusion OR philosophies of full mouth rehabilitation OR oral rehabilitation OR Pankey Mann Schuyler philosophy OR Hobo Twin stage OR Hobo Twin Table OR worn out dentition OR Turner and Missirlian classification”. All collected studies were analyzed and a total of 54 articles and 2 hand searches were extracted, among which 32 articles were selected for the systematic review. Of these 32 articles, 8 were original research studies, 23 case reports and 1 study which comprised 3 case reports were incorporated. Hence, a total of 26 case reports were considered for this systematic review based on CAse REport guidelines.

Statistical Analysis Used:

Qualitative analyisis.

Results:

Among 26 case reports, 15 cases (57.69%) were treated by Pankey Mann Schuyler philosophy, 2 cases (7.69%) by Hobo twin table and 9 cases (34.61%) by Hobo twin stage philosophy. 21 out of 26 cases were introduced for category no. 1 (80.76%) and 4 cases for category no. 2 (15.38%) and only 1case presented for category no.3 (3.84%) of Turner and Missirlian classification.

Conclusion:

No philosophies are universally applicable. Although the most commonly used philosophy is Pankey Mann Schuyler. Hobo Twin stage philosophy is the second most commonly used followed by Hobo Twin table. Maximum patients with worn out dentition are grouped under category no.1 of Turner and Missirlian classification system. Maximum cases of this category are treated by Pankey Mann Schuyler's philosophy.

Functional ectodermal organ regeneration as the next generation of organ replacement therapy

In this decade, substantial progress in the fields of developmental biology and stem cell biology has ushered in a new era for three-dimensional organ regenerative therapy. The emergence of novel three-dimensional cell manipulation technologies enables the effective mimicking of embryonic organ germ formation using the fate-determined organ-inductive potential of epithelial and mesenchymal stem cells. This advance shows great potential for the regeneration of functional organs with substitution of complete original function in situ. Organoids generated from multipotent stem cells or tissue stem cells via establishment of an organ-forming field can only partially recover original organ function owing to the size limitation; they are considered ‘mini-organs’. Nevertheless, they hold great promise to realize regenerative medicine. In particular, regeneration of a functional salivary gland and an integumentary organ system by orthotopic and heterotopic implantation of organoids clearly points to the future direction of organ regeneration research. In this review, we describe multiple strategies and recent progress in regenerating functional three-dimensional organs, focusing on ectodermal organs, and discuss their potential and future directions to achieve organ replacement therapy as a next-generation regenerative medicine.

Alveolar ridge atrophy related to facial morphology in edentulous patients

OBJECTIVES

The morphology of the alveolar process determines the retention and stability of prosthetic restorations, thereby determining the result of the therapy. Considering that the edentulous jaws may be affected by the atrophy process, it was hypothesized that the morphology of the alveolar process of the maxilla may be dependent on the anterior facial height and anatomy of the mandible.

SUBJECTS AND METHODS

Twenty-five healthy edentulous Caucasian individuals were randomly chosen. Each subject underwent a lateral cephalogram before and after prosthetic rehabilitation. During exposition, newly made prostheses were placed in the patient's mouth. Teeth remained in maximal intercuspidation. Morphological parameters were evaluated according to the Ricketts, McNamara, and Tallgren's method.

RESULTS

An inversely proportional association was observed between patient age and the distal part of the maxilla. A statistically significant connection was noted between the vertical dimension of alveolar ridge and anterior total and lower facial height conditioned by prosthetic rehabilitation.

CONCLUSION

The height of the lateral part of the alveolar ridge of the maxilla remains in connection with the anterior total and lower facial height obtained in the course of prosthetic rehabilitation. The vertical dimension of the alveolar ridge of the maxilla seems to be in close relationship with the morphology of the lower jaw.

Practical whole-tooth restoration utilizing autologous bioengineered tooth germ transplantation in a postnatal canine model

Whole-organ regeneration has great potential for the replacement of dysfunctional organs through the reconstruction of a fully functional bioengineered organ using three-dimensional cell manipulation in vitro. Recently, many basic studies of whole-tooth replacement using three-dimensional cell manipulation have been conducted in a mouse model. Further evidence of the practical application to human medicine is required to demonstrate tooth restoration by reconstructing bioengineered tooth germ using a postnatal large-animal model. Herein, we demonstrate functional tooth restoration through the autologous transplantation of bioengineered tooth germ in a postnatal canine model. The bioengineered tooth, which was reconstructed using permanent tooth germ cells, erupted into the jawbone after autologous transplantation and achieved physiological function equivalent to that of a natural tooth. This study represents a substantial advancement in whole-organ replacement therapy through the transplantation of bioengineered organ germ as a practical model for future clinical regenerative medicine.

Whole Tooth Regeneration as a Future Dental Treatment

Dental problems caused by dental caries, periodontal disease and tooth injury compromise the oral and general health issues. Current advances for the development of regenerative therapy have been influenced by our understanding of embryonic development, stem cell biology, and tissue engineering technology. Tooth regenerative therapy for tooth tissue repair and whole tooth replacement is currently expected a novel therapeutic concept with the full recovery of tooth physiological functions. Dental stem cells and cell-activating cytokines are thought to be candidate approach for tooth tissue regeneration because they have the potential to differentiate into tooth tissues in vitro and in vivo. Whole tooth replacement therapy is considered to be an attractive concept for next generation regenerative therapy as a form of bioengineered organ replacement. For realization of whole tooth regeneration, we have developed a novel three-dimensional cell manipulation method designated the "organ germ method". This method involves compartmentalisation of epithelial and mesenchymal cells at a high cell density to mimic multicellular assembly conditions and epithelial-mesenchymal interactions in organogenesis. The bioengineered tooth germ generates a structurally correct tooth in vitro, and erupted successfully with correct tooth structure when transplanted into the oral cavity. We have ectopically generated a bioengineered tooth unit composed of a mature tooth, periodontal ligament and alveolar bone, and that tooth unit was engrafted into an adult jawbone through bone integration. Bioengineered teeth were also able to perform physiological tooth functions such as mastication, periodontal ligament function and response to noxious stimuli. In this review, we describe recent findings and technologies underpinning whole tooth regenerative therapy.

Differences between centric relation and maximum intercuspation as possible cause for development of temporomandibular disorder analyzed with T-scan III

Objective:

To compare subjects from the group with fixed dentures, the group who present temporomandibular disorders (TMDs) and a control group considering centric relation (CR) and maximum intercuspation (MIC)/habitual occlusion (Hab. Occl.) and to analyze the related variables also compared and analyzed with electronic system T-scan III.

Materials and Methods:

A total of 54 subjects were divided into three groups; 17 subjects with fixed dentures, 14 with TMD and 23 controls-selection based on anamnesis-responded to a Fonseca questionnaire and clinical measurements analyzed with electronic system T-scan III. Occlusal force, presented by percentage (automatically by the T-scan electronic system) was analyzed in CR and in MIC.

Results:

Data were presented as mean ± standard deviation and differences in P < 0.05 were considered significant. After measurements of the differences between CR and MIC in the three groups were noticed varieties but the P > 0.05 it was not significant in all three groups.

Conclusion:

In our study, it was concluded that there are not statistically significant differences between CR and MIC in the group of individuals without any symptom or sign of TMD although there are noticed in the group with TMD and fixed dentures disharmonic relation between the arches with overload of the occlusal force on the one side.

Functional tooth restoration utilising split germs through re-regionalisation of the tooth-forming field

The tooth is an ectodermal organ that arises from a tooth germ under the regulation of reciprocal epithelial-mesenchymal interactions. Tooth morphogenesis occurs in the tooth-forming field as a result of reaction-diffusion waves of specific gene expression patterns. Here, we developed a novel mechanical ligation method for splitting tooth germs to artificially regulate the molecules that control tooth morphology. The split tooth germs successfully developed into multiple correct teeth through the re-regionalisation of the tooth-forming field, which is regulated by reaction-diffusion waves in response to mechanical force. Furthermore, split teeth erupted into the oral cavity and restored physiological tooth function, including mastication, periodontal ligament function and responsiveness to noxious stimuli. Thus, this study presents a novel tooth regenerative technology based on split tooth germs and the re-regionalisation of the tooth-forming field by artificial mechanical force.

Occlusal concepts in full mouth rehabilitation: an overview

Restoration of occlusion in patients with severely worn dentition is a challenging situation as every case is unique in itself. There is great apprehension involved in reconstructing debilitated dentition due to widely divergent views concerning the choice of an appropriate occlusal scheme for successful full mouth rehabilitation. This article is an overview of the various occlusal concepts/philosophies in full mouth rehabilitation which will help the clinician select an appropriate occlusal scheme for an individual case.

Functional tooth restoration by next-generation bio-hybrid implant as a bio-hybrid artificial organ replacement therapy

Bio-hybrid artificial organs are an attractive concept to restore organ function through precise biological cooperation with surrounding tissues in vivo. However, in bio-hybrid artificial organs, an artificial organ with fibrous connective tissues, including muscles, tendons and ligaments, has not been developed. Here, we have enveloped with embryonic dental follicle tissue around a HA-coated dental implant, and transplanted into the lower first molar region of a murine tooth-loss model. We successfully developed a novel fibrous connected tooth implant using a HA-coated dental implant and dental follicle stem cells as a bio-hybrid organ. This bio-hybrid implant restored physiological functions, including bone remodelling, regeneration of severe bone-defect and responsiveness to noxious stimuli, through regeneration with periodontal tissues, such as periodontal ligament and cementum. Thus, this study represents the potential for a next-generation bio-hybrid implant for tooth loss as a future bio-hybrid artificial organ replacement therapy.

Functional tooth regenerative therapy: tooth tissue regeneration and whole-tooth replacement

Oral and general health is compromised by irreversible dental problems, including dental caries, periodontal disease and tooth injury. Regenerative therapy for tooth tissue repair and whole-tooth replacement is currently considered a novel therapeutic concept with the potential for the full recovery of tooth function. Several types of stem cells and cell-activating cytokines have been identified in oral tissues. These cells are thought to be candidate cell sources for tooth tissue regenerative therapies because they have the ability to differentiate into tooth tissues in vitro and in vivo. Whole-tooth replacement therapy is regarded as an important model for the development of an organ regenerative concept. A novel three-dimensional cell-manipulation method, designated the organ germ method, has been developed to recapitulate organogenesis. This method involves compartmentalisation of epithelial and mesenchymal cells at a high cell density to mimic multicellular assembly conditions and epithelial-mesenchymal interactions. A bioengineered tooth germ can generate a structurally correct tooth in vitro and erupt successfully with the correct tooth structure when transplanted into the oral cavity. We have ectopically generated a bioengineered tooth unit composed of a mature tooth, periodontal ligament and alveolar bone, and that tooth unit was successfully engrafted into an adult jawbone through bone integration. Such bioengineered teeth were able to perform normal physiological tooth functions, such as developing a masticatory potential in response to mechanical stress and a perceptive potential for noxious stimuli. In this review, we describe recent findings and technologies underpinning tooth regenerative therapy.

Diagnosis and management of occlusal wear: a case report

The rationale for doing full mouth rehabilitation are, when occlusal forces become traumatic hampering the health of periodontal tissues, extensive occlusal diseases, trauma, temporomandibular joint disease and congenital disorders with malformed dentition. Literature exposes that full mouth fixed rehabilitation is one of the taxing procedures in the field of Prosthodontics. A critical aspect for successful occlusal rehabilitation is to determine the aetiology, correct sequence of treatment and most importantly the occlusal vertical dimension and centric relation in which to plan the treatment. A systematic approach in managing these patients can lead to a predictable and favourable prognosis. This article presents the stages of prosthodontic rehabilitation, from diagnosis to final treatment and follow-up, of a bruxer patient with severely worn dentition.

Occlusal stability

Occlusion is the foundation for clinical success in fixed, removable, and implant prosthodontic treatment. Understanding those principles is critical when restoring a patient's occlusion. Many philosophies, devices, and theories of occlusion have evolved based on anecdotal clinical observations and applied geometric perceptions. The literature has reported these classic and contemporary occlusal concepts. As evidence-based dentistry emerged, it championed scrutiny of previously held beliefs, resulting in the abandonment of many pragmatic, yet beneficial occlusal procedures. The impetus toward scientific discovery, whereby factual information might be universally applied in dental education and clinical practice, has renewed interest in occlusal studies.

Reproducibility of habitual intercuspation in vivo

OBJECTIVES

The aim of this in vivo study was to investigate how reproducible individuals find their habitual intercuspation.

METHODS

A new type of highly accurate measuring procedure was involved using an intraoral optical scanning device (Cerec Bluecam). First, a pilot test investigated the accuracy of the procedure within a standardized setting. With regard to the in vivo study, fifteen participants with full dentition were selected. For each of these individuals, eight scans were taken both in the morning and in the afternoon. Furthermore, during each session, scans were taken both in horizontal and upright position. In order to compare this to ubiquitous used processes, plaster replicas of five individuals were investigated as well. The scans were analysed, and the differences in the position of the lower jaw were calculated by a specialized superimposition program (n=570 comparisons/OraCheck).

RESULTS

The results showed that there was no significant difference between the time of day and the position of the patient. The overall mean ± SD value for locating the habitual intercuspation was 42 ± 34 μm, however ranging from 22 ± 9 μm to 77 ± 58 μm for single individuals. On the other hand, the differences in positioning plaster replicas reached a mean of 135 ± 77 μm.

CONCLUSIONS

The reproducibility of the habitual intercuspation can be obtained under in vivo conditions by a newly developed and highly accurate measuring procedure. Individuals with full dentition show values in average of 42 μm.

CLINICAL SIGNIFICANCE

Determining the occlusal jaw relation is an important precondition in restorative dentistry and many methods are proposed for a proper occlusal registration. Although much is known about in vitro accuracy of these techniques, little is known how reproducible the habitual occlusal position itself is found between individuals.

Full-mouth rehabilitation of severely worn dentition due to soda swishing: a clinical report

Diagnosis and treatment planning of severely worn dentition are complex and complicated. Erosion is one of the common causes of lost tooth surface. Defining the etiology of the erosion is essential before proceeding with treatment to be able to provide the most predictable treatment outcome. Multiple specialists including psychologists, family medicine practioners, and social workers should be involved in the diagnosis and the prevention of a continuing erosion process. The treatment plan should be based on the severity of the tooth surface lost. It can range from simple direct restorations to a full-mouth rehabilitation. This clinical report is a detailed description of a complex prosthodontic diagnostic index class IV patient based on current evidence-based dentistry.

Centric relation definition: a historical and contemporary prosthodontic perspective

Centric relation (CR) is a core topic of dentistry in general and prosthodontics in particular. The term CR has become thoroughly confusing because of many conflicting definitions. Unfortunately definition of CR changed repeatedly over past ten decades. All the existing definitions in the dental literature, for the past 81 years, are segregated into definitions from 1929 to 1970, 1970-1980, and 1980-2010 and are critically analyzed. Both PubMed (key words: centric relation/centric jaw relation) and hand searches were employed, from citation in other publications, to identify relevant articles in English language peer reviewed PubMed journals from 1956 to 2010; although the review is from 1929. Numerous definitions for CR have been given, however, no consensus exists and the definition given by a current glossary of prosthodontic terms is confusing. It relates CR to many clinically invisible parts and cannot guide a dental surgeon to record the CR following its description. The purpose of this article is not only to review all the definitions critically but to propose a self explanatory definition to minimize the confusion in the minds of dental practitioners and students for better understanding of the concept of CR. Centric relation is clinically significant since it is the only clinically repeatable jaw relation and the logical position to fabricate prosthesis.

Prosthetic rehabilitation of a cleidocranial dysplasia patient with vertical maxillofacial deficiency: a clinical report

Cleidocranial dysplasia (CCD) is a rare congenital disorder characterized by skeletal and dental anomalies. This clinical report describes the prosthodontic approach to treating a CCD patient who presented with decreased facial height and relative mandibular protrusion due to maxillary hypoplasia after orthodontic treatment. Functional and esthetic rehabilitation was achieved using telescopic detachable prostheses in the maxilla and osseointegrated implants and metal-ceramic fixed dental prostheses in the mandible. These treatment approaches precluded the need for orthognathic surgical correction and presented a favorable prognosis during the 5-year observation period.

Clinical considerations for increasing occlusal vertical dimension: a review

The purpose of this article is to discuss the clinical considerations related to increasing the occlusal vertical dimension (OVD) when restoring a patient's dentition. Thorough extraoral and intraoral evaluations are mandatory to assess the suitability of increasing OVD. In the literature, multiple techniques have been proposed to quantify OVD loss. However, the techniques lack consistency and reliability, which in turn affects the decision of whether to increase the OVD. Therefore, increasing OVD should be determined on the basis of the dental restorative needs and aesthetic demands. In general, a minimal increase in OVD should be applied, though a 5 mm maximum increase in OVD can be justified to provide adequate occlusal space for the restorative material and to improve anterior teeth aesthetics. The literature reflects the safety of increasing the OVD permanently, and although signs and symptoms may develop, these are usually of an interim nature. Whenever indicated, the increase in OVD should be achieved with fixed restorations rather than a removable appliance, due to the predictable patient adaptation. The exception to this is for patients with TMD, where increasing the OVD should still be achieved using removable appliances to control TMD-associated symptoms before considering any form of irreversible procedure.

Methodological challenges in the study of dental occlusion

This narrative review describes the methodological challenges in the study of dental occlusion. The reigning confusion about the scope of this topic is discussed, and a conceptual framework for understanding dental occlusion research is suggested. The characteristics of clinical studies used in the study of dental occlusion are presented within this proposed framework consisting of a triad comprising the relative positions of the teeth-mandible-maxilla, the oral functions and oral appearance. Challenges in the preparation for a clinical study of dental occlusion are reviewed, which include a discourse on the objectives of a clinical study and appropriateness of different study designs. Guidelines are provided for the conduct of studies with a central focus on dental occlusion and diagnostic tests, prognosis, therapy and aetiology, respectively. Summarising chapters present methodological challenges in designing a clinical study of dental occlusion and threats to the proper conduct of a clinical study.

Occlusal concepts application in resolving implant prosthetic failure: case report

The prosthetic management of a poor implant treatment is presented in this case report. The recommended occlusion concepts for implant-supported prostheses were applied for the resolution of the case. The rehabilitation of the posterior segments provided a mutually protected occlusion with adequate distribution of the axial and lateral bite forces with stable posterior occlusion. The clinical exam indicated the need for modification in the vertical dimension of occlusion. Sufficient interocclusal rest space was present to test the alteration in the vertical dimension. The aim was to achieve an occlusion scheme that followed four specific criteria: (1) centric contacts and centric relation of the jaw-to-jaw position; (2) anterior guidance only; (3) shallow anterior angle of tooth contact; and (4) vertical dimension of occlusion with acceptable tooth form and guidance. The success of an oral rehabilitation relies in following the aforementioned criteria, appropriate interaction between the dental laboratory technician and the clinician, careful elaboration of the provisional rehabilitation with all the desired details to be reproduced in the final prosthetic restoration and sufficient follow-up time of the provisional prostheses before placing the final restoration.