The association between dental wear and reduced vertical dimension of the face: a morphologic study on human skulls

Increasing Vertical Dimension of Occlusion (VDO): Review

The need to increase the Vertical Dimension of Occlusion (VDO) to restore lost dental function or optimise specific dental treatments is a common occurrence in daily dental practice. The common belief that the Vertical Dimension at Rest (VDR) is fixed hinders the development of restorations with a VDO that encroaches on or surpasses the interocclusal rest space (IRS), thereby preventing potential tissue damage to the masticatory apparatus. Recent studies have shown that the mandible rest position falls within a range termed as the "comfort zone". The range of this zone may vary from one person to another and within the same person over time due to factors such as age or health status. In this review, we have concluded that a permanent increase in the VDO, once indicated, is a safe procedure for dentulous patients. However, it is important to minimise the extent of the increase to simplify the prosthodontics treatment process. An inter-incisal increase exceeding 5 mm is seldom needed. Moreover, it is important to consider the functional, aesthetic, and biological elements associated with VDO. The biological and functional environment closely related to the VDO had great adaptive capacities, which have for a historically been underestimated. Patient adaptation has been observed in dentate patients, edentulous patients, and even cases involving implant-supported prostheses. Muscle relaxation and changes in muscle length are likely the primary adaptation mechanisms, rather than the restoration of the original VDO through dentoalveolar maturation. Intervention with a fixed restoration is more predictable and results in a higher and more rapid level of adaptation. Finally, the increase should include the entire arch to prevent relapse of the VDO to its previous value, and changes in VDO should be assessed by utilising temporary diagnostic restorations for a period before implementing definitive prostheses, in order to evaluate the adaptive muscle response.

Outcomes and Complications of 33 Soft-Milled Cobalt-Chromium-Ceramic Full-Arch Screw-Retained Implant-Supported Prostheses: A Retrospective Study with up to 10-Year Follow-up

This retrospective study assessed outcomes and complications related to implants and prostheses in edentulous patients treated with soft-milled cobalt-chromium-ceramic full-arch screw-retained implant-supported prostheses (SCCSIPs). After the final prosthesis was delivered, patients participated in an annual dental check-up program, including clinical and radiographic assessments. Outcomes of implants and prostheses were evaluated, and biological and technical complications were categorized as major or minor. Implant and prosthesis cumulative survival rates were assessed using the life table analysis. A total of twenty-five participants (mean age 63.6 ± 7.3 years) with 33 SCCSIPs were observed for a mean of 68.9 ± 27.9 months (range 1–10 years). A total of 7 out of 245 implants were lost, with no effect on prosthesis survival, leading to cumulative survival rates of 97.1% for implants and 100% for prostheses. The most recurrent minor and major biological complications were soft tissue recession (9%) and late implant failure (2.8%). Among 25 technical complications, porcelain fracture was the only major technical complication, requiring prosthesis removal (1%). Porcelain chipping was the most frequent minor technical complication, affecting 21 crowns (5.4%), which required polishing only. At the end of the follow-up, 69.7% of the prostheses were free of technical complications. Within the limitations of this study, SCCSIP showed promising clinical performance after 1–10 years.

An interdisciplinary approach for reconstruction of worn dentition

Complete tooth wear dentition is multifactorial and has challenges with diagnosis and etiology. Their rehabilitation often requires orthognathic surgery, orthodontics, periodontal surgery, and prosthodontic guidelines for occlusion with harmonious facial and dental esthetics. A patient needs a multidisciplinary approach with systematic analysis to formulate evidence-based approach to improve function and esthetics. Contemporary periodontal therapy also encompasses esthetic treatment where needs are frequently associated with changes in tooth size, shape, proportion, and balance that can adversely affect smile appearance. The article provides an evidence-based guideline for reconstruction of a worn dentition. The completed work includes crown lengthening, provisionalization, socket shield technique, oral implants, and gain in lost vertical dimension with occlusion correction and minimally invasive prosthetic restorations.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

The effect of tooth wear, age and sex on facial height assessed by soft tissue analysis

AIM

The aim of the study was to evaluate the effects of tooth wear, age and sex on facial height measurements based on soft tissue analysis.

METHODS

One hundred and twelve subjects (45 males and 67 females), 19-80 years of age (mean 43 ± 0.9 years), which were divided into three age groups, met the inclusion criteria. Tooth wear was assessed using a 5-point ordinal scale (0-4). Based on the tooth wear score, three groups were defined: mild, moderate and severe wear. Facial height was evaluated based on soft tissue measurements using frontal facial photographs. The dimension of the upper facial height (UFH) and lower facial height (LFH) and the ratio between the two (R-U-L) were measured.

RESULTS

Facial height dimensions (UFH, LFH) were significantly different between the three age groups and between the three tooth wear groups. Both the UFH and LFH measurements had a weak positive correlation with age (r = .40; r = .41, respectively) and with tooth wear (r = .40; r = .41, respectively). The R-U-L showed a significant difference (P < .001) between sexes as males showed slightly lower ratio compared with females; however, the R-U-L was not dependent upon age or tooth wear.

CONCLUSIONS

This study demonstrated that although facial height is affected by age and tooth wear, the proportion between the upper to lower facial segments is constant and is not affected by the same parameters. A statistically significant difference in the R-U-L relative to sexes was noted.

Non-carious lesions in patients treated for functional temporomandibular disorders

Introduction. Numerous clinical symptoms found in patients with temporomandibular disorders include non-carious lesions, such as V-shaped lesions, wear facets, enamel cracks, and impressions on the tongue or changes in the buccal mucosa. In addition, loosening and dislocation of teeth may occur.

Aim. The aim of the study was to obtain a clinical assessment of the prevalence and severity of non-carious lesions of dental hard tissues (attrition and abrasion) in patients treated for functional temporomandibular disorders.

Material and methods. The clinical research was performed among 45 patients of both genders, aged 16-38 years, treated at the Department of Functional Masticatory Disorders at the Medical University of Lublin, Poland. The study group consisted of 30 patients with diagnosed temporomandibular disorders. The control group included 15 individuals with no diagnosed temporomandibular disorders. The control group was selected using the method of analogues (considering age, gender and dental status). The examinations were performed before the treatment and twelve weeks after its beginning.

Results. The study found significantly higher values of the prevalence and severity of attrition in the patients group, in comparison with the control group (p < 0.05). In the case of abrasion, higher values of the studied variables of prevalence and severity of lesions in the patients, compared to controls, were also found, but the differences were not statistically significant (p > 0.05).

Conclusions. Attrition occurs more frequently and is more severe in patients with diagnosed temporomandibular disorders than in those without such diagnosis. However, no significant differences have been found in the prevalence and severity of abrasion in both groups.

[Cone-beam computed tomography-synthesized cephalograms for evaluating the vertical dimension of occlusions]

OBJECTIVE

The accuracy of the occlusion vertical dimensions of edentulous Han patients from Yunnan province was compared and analyzed on the basis of cone-beam computed tomography (CBCT)-synthesized cephalograms, closest speaking space method, and interocclusal distance.

METHODS

A database correlating the CBCT head lateral images of Han patients from Yunnan province with normal occlusal conditions was first constructed. Then, five edentulous Han patients aged 63-78 years old from Yunnan Province were selected. NNT.View software was used to measure and analyze hard tissue cephalometric radiographs that had been transformed by the CBCT marker. The radiographs were then combined with the normal population database for the assessment of occlusion vertical dimensions. The occlusion vertical dimensions determined on the basis of CBCT-synthesized cephalograms, the closest speaking space method, and the free-way space were analyzed.

RESULTS

The closest speaking space method was used as the standard control group, the differences between seven methods and the closest speaking space method were analyzed. The seven methods include free-way space method and six CBCT-synthesized cephalograms methods (N-ANS/ANS-Me, S-Go/N-Me, ANS-Gn/N-ANS, ANS-FH/Me-FH, ANS-Xi-Pm, and CA/LA). The seven methods were highly consistent with the closest speaking space method (intraclass correlation coefficient>0.986). The absolute values of the differences between the methods of free-way space, N-ANS/ANS-Me, S-Go/N-Me and the closest speaking space method were lower than those of the other four groups (P<0.05), while the differences between ANS-FH/Me-FH and the closest speaking space method was higher than those other groups (P<0.05).

CONCLUSIONS

CBCT-synthesized cephalograms, with the exception of ANS-FH/Me-FH, can provide references for the clinical evaluation of the occlusion vertical dimensions of patients with edentulous jaws.

Restoration of the Occlusal Vertical Dimension with an Overlay Removable Partial Denture: A Clinical Report

The process of tooth loss throughout life associated with severe occlusal wear may pose a challenge in the rehabilitation of partially edentulous arches. In these cases, many therapeutic procedures are necessary because each tooth must be restored to obtain the correct anatomical contour and recover the occlusal vertical dimension (OVD). A removable partial denture (RPD) with occlusal/incisal coverage, also known as an overlay RPD, is an alternative treatment option with fewer interventions, and, consequently, lower cost. This clinical report reviews the principles involved in the clinical indication for an overlay RPD, as well as the necessary planning and execution, to discuss the feasibility and clinical effectiveness of this treatment, identifying the indications, advantages, and disadvantages of this procedure through the presentation of a clinical case. The overlay RPD can be an alternative treatment for special situations involving partially edentulous arches in patients who need reestablishment of the OVD and/or realignment of the occlusal plane, and it can be used as a temporary or definitive treatment. The main advantages of this type of treatment are its simplicity, reversibility, and relatively low cost; however, further studies are needed to ensure the efficacy of this treatment option.