Biomechanics of occlusion - implications for oral rehabilitation

Oral health and orofacial pain in people with dementia admitted to acute hospital wards: observational cohort study

Background

Orofacial pain in people with dementia is difficult to detect, and often under-treated. Our aim was to investigate the prevalence of orofacial pain in people with dementia in acute hospitals in the UK. Secondary aims were to examine oral health status and explore associations between orofacial pain and oral health factors.

Methods

This cross-sectional observational study was carried out in two UK hospitals. Using the Orofacial Pain Scale in Non-Verbal Individuals (OPS-NVI) to identify orofacial pain, 101 participants with dementia, admitted to acute medical wards, were observed for at least 3 min during rest and chewing. Verbal participants were then asked about presence of orofacial pain, using self-report pain scales. Finally, a brief oral assessment was performed.

Results

Orofacial pain, assessed with the OPS-NVI, was present in 11.9% (95% C.I. 5.9, 18.8) of participants at rest and 21.9% (95% C.I. 14.6, 31.3) whilst chewing. Participants who were no longer able to self-report pain were significantly more likely to experience orofacial pain. Oral health in both dentate and edentate participants was poor. Brush frequency, indication of chewing quality, consistency of the food, presence of extra-oral abnormalities, person who performed mouth care, and oral hygiene in dentate participants were significant predictors for the presence of orofacial pain.

Conclusion

Improving oral care in acute hospital patients with dementia, particularly those who cannot self-report pain, may significantly reduce pain and suffering in this population.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0810-7) contains supplementary material, which is available to authorized users.

Correlations between fracture load of zirconia implant supported single crowns and mechanical properties of restorative material and cement

Zirconia implants that were restored with veneered zirconia displayed severe chipping rates of the restorations in clinical studies. Purpose of this study was to evaluate the fracture load of different zirconia implant supported monolithic crown materials (zirconia, alumina, lithium disilicate, feldspar ceramic and polymer-infiltrated ceramic) cemented with various cements (Harvard LuteCem SE, Harvard Implant Semi-permanent, Multilink Automix, VITA Adiva F-Cem). Flexural strength and fracture toughness of crown materials and compressive strength of the cements were measured. Fracture load values of crowns fabricated from lithium disilicate, feldspar ceramic and polymer-infiltrated ceramic were increased when cement with high compressive strength was used. Fracture loads for zirconia and alumina crowns were not influenced by the cement. Flexural strength and fracture toughness of the ceramics correlated linearly with the respective fracture load when using adhesive cement with high compressive strength. To achieve sufficient fracture load values, cementation with adhesive cement is essential for feldspar and polymer-infiltrated ceramic.

A hemispherical contact model for simplifying 3D occlusal surfaces

STATEMENT OF PROBLEM

Currently, dental articulators can recreate mandibular movements and occlusal contacts. However, whether virtual articulators can also provide information about occluding dental surfaces, functional movements, and the mandibular condyles is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the occluding surfaces on dental casts obtained from a patient and approximate them to a hemispherical contact model. Both models were tested by digitizing the Dentatus ARL dental articulator.

MATERIAL AND METHODS

A combination of photogrammetry and structure from motion methods were used to scan a Dentatus ARL articulator and representative dental casts. Using computer-aided engineering and finite element analysis, contact points and action vectors to the forces on occluding surfaces and condyles were obtained for cast and hemispherical models. This experiment was performed using centric occlusion and 3 different condylar inclinations. The Kruskal-Wallis 1-way analysis of variance on ranks test was used to allow all pairwise comparisons between condylar inclination and mechanical action vector values in each location (α=.05).

RESULTS

Action vectors from the cast model and each location of the hemispherical model were calculated to show the mechanical consequences and the similarity among models. Overall, no significant differences were observed for action vectors (A20 versus A40 versus A60) at each location (dental cast/hemisphere, right condylar, and left condylar) in the analysis of dental casts and the hemisphere model (.382≤P≤.999).

CONCLUSIONS

This study provided graphical information that may assist the dental professional in determining which occlusal contacts should be modified to attain condylar and balanced centric occlusion.