Importance of Osseoperception and Tactile Sensibility during Masticatory Function in Different Prosthetic Rehabilitations: A Review

Occlusion and Biomechanical Risk Factors in Implant-Supported Full-Arch Fixed Dental Prostheses-Narrative Review

The biophysiological differences between teeth and dental implants and the issue of occlusal overload, although controversial, form the basis for the management of occlusion in implant-supported full-arch fixed dental prostheses (ISFAFDPs). Although there is currently a lack of scientific evidence on occlusal management, it is clear that the favorable prognosis of ISFAFDPs is linked to a correct understanding of the biomechanical principles involved. In the design of ISFAFDPs, the lack of proprioceptive feedback requires special attention to biomechanical factors: minimizing overloading complications and providing biomechanical stability are among the main goals of the occlusion. In ISFAFDPs, the occlusion must be decided on the basis of several factors that influence the loads on prosthesis and implants: each case must be evaluated individually and requires a personalized occlusion. The main aim of this narrative review is to provide an overview of the occlusal principles and materials that can be used in ISFAFDPs based on the data currently available in the literature. Practical clinical recommendations for the occlusion management of ISFAFDPs and a biomechanical risk score index to personalize implant-prosthetic treatment are proposed.

Use of T-Scan III in analyzing occlusal changes in molar fixed denture placement

BACKGROUND

This study aims to analyze the longitudinal variation of occlusal force distribution prior to and after fixed restoration for molar full-crowns with T-SCAN III which provide reference for occlusal adjustment and long-term maintenance.

METHODS

We enrolled a total of 20 patients who received conventional restorative treatment for molars. The occlusion examination was conducted in 3 stages (before placement, immediately after placement, and 3 months after placement) using T-SCAN III (Tekscan South Boston, MA, USA, 10.0) to examine and measure the occlusal contact areas of the full dentition.

RESULTS

The results indicated that the occlusal force distribution in the molar region of the patients changed before and after the fixed restoration, but the percentages of occlusal force in the dental arch of the molar did not differ significantly before and after the restoration (P > 0.05). Three months after the fixed restoration, the percentage of occlusal force in the restored dental arches of lateral teeth increased significantly (P < 0.05).

CONCLUSION

The results of this study indicated that the occlusal forces of the patients changed with tooth movement and adaptation, which is mainly reflected in the increasing occlusal force. Quantitative occlusal force analysis using T-SCAN III occlusal analyzer can provide more objective and accurate data to effectively guide clinical occlusion adjustments.

Clinical Outcomes of Three versus Four Mini-Implants Retaining Mandibular Overdenture: A 5-Year Randomized Clinical Trial

Background and Objectives: Due to a lack of long-term clinical studies that would clarify whether the insertion of three mini-implants (MDIs) can be as successful treatment as the insertion of four MDIs for the retention of mandibular overdentures (ODs), this 5-year prospective cohort study was set up. Materials and Methods: Participants (n = 83) randomly received either four or three MDIs and a mandibular OD. Clinical examinations were performed at the baseline, as well as after one, three, and five years, respectively. A total of 73 participants (38 in the four-MDI and 35 in the three-MDI groups) partook in the study. The marginal bone level change, success and survival rates, and prosthodontic maintenance were assessed. Results: Repeated measures showed that the mean peri-implant bone loss increased progressively at a small amount over five years in both groups (four-MDI group = -0.36 ± 0.74; three-MDI group = -0.33 ± 0.27 mm; p < 0.05). However, an ANCOVA revealed no significant effects of the group (no significant difference between the three- and the four-MDI groups; F = 0.085; p = 0.771), gender (F = 0.023; p = 0.88), or covariate age (F = 1.95; p = 0.167) on the dependent variable: the 5-year MBL change. The success rate (together with successful survival) was 93.8% in the four-MDI group and 91.7% in the three-MDI group. The log-rank (Mantel-Cox) test revealed no significant differences between them (X2 = 0.373; p = 0.541). Conclusions: In patients with narrow ridges, the insertion of three MDIs in the mandible for overdenture retention can be equally as successful as the insertion of four MDIs.

Mini-Implants Retaining Removable Partial Dentures in Subjects without Posterior Teeth: A 5-Year Prospective Study Comparing the Maxilla and the Mandible

Background and objectives: Long-term studies of clinical outcomes of mini-implants (MDIs) in the first premolar/canine sites retaining a bilateral free-ending removable partial dentures (RPD) in Kennedy class I subjects have not been well documented. The aim was to assess clinical outcomes in a prospective 5-year cohort study comparing the mandible and maxilla. Material and Methods: Participants (n = 92) who received two MDIs each and a new RPD were reviewed after one, three and five years. A total of 71 participants (82 mini-implants in the mandible; 58 in the maxilla) completed the study. Marginal bone level change, success, survival rates, Modified Plaque (MPI) and Bleeding Indices (MBI) were assessed. Results: The five-year success rate was 93.3% and 93.4% (p > 0.05), in the mandible and the maxilla, respectively. Mean peri-implant bone loss (MBL) increased significantly over five years (p < 0.01) to 0.50 mm in the mandible and 0.52 mm in the maxilla. Age had a significant effect on the MBL (higher rates in younger participants), while jaw of insertion, gender, and antagonistic jaw status did not. MPI and MBI were not significantly correlated with MBL. Conclusions: The insertion of two MDIs in previous first premolar/canine sites for retention of a free-end saddle RPD can be a successful treatment modality in subjects with narrow alveolar ridges.

Active Tactile Sensibility in Implant Prosthesis vs. Complete Dentures: A Psychophysical Study

BACKGROUND AND OBJECTIVES

Proprioceptive information from natural dentition and adjacent oral tissues enables correct masticatory function, avoiding damage to the teeth. Periodontium is the main source of this relevant information, and when a tooth is lost, all this proprioceptive sensibility relies on receptors from muscles, the mucous membrane or the temporomandibular joint, and this sensibility gets worse. Active tactile sensibility measures this proprioceptive capability in microns by psychophysical studies consisting of introducing thin metal foils between patients' dental arches during chewing to see if they are able to notice them or not. Osseoperception is a complex phenomenon that seems to improve this sensibility in patients wearing dental implants. The objective of this investigation is to measure this sensibility in different prosthetic situations by performing a psychophysical investigation.

MATERIAL AND METHODS

We divided 67 patients in three groups depending on their prosthetic situation and performed a psychophysical study by introducing aluminium foils of different thicknesses in order to establish an active tactile sensibility threshold in every group. We also measured variables such as prosthetic wearing time, age or gender to see how they may influence threshold values. We used Student's t-test and Mann-Whitney U tests to analyse these results.

RESULTS

Active tactile sensibility threshold values in implants are lower than those from complete dentures but higher than values in natural dentition. However, values in implants are closer to natural dentition than complete denture values. Age, gender or prosthetic wearing time have no influence in active tactile sensibility thresholds.

CONCLUSION

Active tactile sensibility threshold values depend on prosthetic rehabilitations and the mechanoreceptors involved in every situation. Implant prosthesis presents an increased active tactile sensibility thanks to osseoperception phenomenon.

Duração da mastigação e da fase oral da deglutição em idosos com diferentes condições dentárias: análise clínica

RESUMO Objetivo: mensurar o tempo total da mastigação e da fase oral da deglutição em idosos saudáveis, considerando diferentes consistências alimentares, a presença de dentes naturais e o tipo de reabilitação oral protética, bem como realizar comparação entre as condições dentárias e as consistências. Métodos: estudo transversal com 57 idosos saudáveis, entre 60 e 82 anos, distribuídos em grupo dentado (D) (n=15) e grupos reabilitados: próteses parciais fixas ou removíveis em uma ou ambas as arcadas (PP) (n=15); prótese total removível maxilar e mandibular (PTR) (n=15); prótese total - prótese removível superior e prótese implanto-suportada inferior (PTIS) (n=12). O tempo de duração (segundos) da mastigação e da fase oral da deglutição foi medido nas consistências: sólida (pão francês), pudim (10 ml) e líquida (10 ml). Resultados: idosos dentados saudáveis apresentaram os intervalos: líquido=1,07±0,35 s; pudim=3,48±1,76 s; e sólido=27,88±7,11 s. Foram observadas diferenças estatisticamente significativas entre os grupos D e PTIS (p=0,0056) e entre D e PTR (p=0,0056) para líquido. Para todos os grupos, houve aumento estatisticamente significante entre as consistências líquida e sólida e entre pastosa e sólida (p<0,001). Conclusões: idosos dentados apresentaram menor tempo de fase oral da deglutição para líquidos do que idosos edêntulos totais reabilitados, mas não diferente dos idosos com prótese parcial. O tempo de mastigação e deglutição do alimento sólido foi maior que o das demais consistências, independente da condição dentária.

Duration of mastication and oral phase of swallowing in the elderly with different dental conditions: a clinical analysis

ABSTRACT Purpose: to measure the total time of mastication and oral phase of swallowing in healthy elderly people, considering different food consistency, the presence of natural teeth, and the type of prosthetic oral rehabilitation, as well to compare dental conditions and consistencies. Methods: a cross-sectional study with 57 healthy elderly people, aged between 60 and 82 years, divided into: dentate group (D) (n=15); and rehabilitated groups; PD: fixed or removable partial dentures in one or both arches (n=15); CRD: maxillary and mandibular complete removable dentures (n=15); ISCD: complete dentures - maxillary removable denture and mandibular implant-supported dentures (n=12). The duration time (seconds) of chewing and of the oral phase of swallowing was measured in the consistencies: solid (a roll slice), pudding (10 ml) and liquid (10 ml). Results: healthy dentate elderly subjects had the following intervals: liquid=1.07±0.35 s; pudding=3.48±1.76 s; and solid=27.88±7.11 s. Statistically significant differences were observed between the D and ISCD groups (p=0.0056) and between D and CRD (p=0.0056) for liquid. For all groups, there was a statistically significant increase between liquid and solid consistencies and between pasty and solid ones (p<0.001). Conclusions: the dentate elderly had shorter oral phase time of swallowing for liquids than the rehabilitated edentulous elderly, but not different from the elderly with partial dentures. Chewing and swallowing time for solid food was longer than that for the other consistencies, regardless of dental condition.