Does Periodontal Tactile Input Uniquely Increase Cerebral Blood Flow in the Prefrontal Cortex?

We previously studied the effect of peripheral sensory information from sensory periodontal ligament receptors on prefrontal cortex (PFC) activity. In the dental field, an alternative dental implant without periodontal sensation can be applied for missing teeth. In this study, we examine whether periodontal tactile input could increase cerebral blood flow (CBF) in the PFC against elderly patients with dental implants lacking periodontal tactile (implant group), elderly individuals with natural teeth (elderly group), and young individuals with natural teeth (young group). The experimental task of maintaining occlusal force as closed-loop stimulation was performed. Compared with the young group, the elderly group showed significantly lower CBF. Contrastingly, compared with the young group, the implant group showed significantly lower CBF. There were no significant differences between the elderly and implant groups. Regarding the mean occlusal force value, compared with the young group and the elderly group, the implant group had a numerically, but not significantly, larger occlusal force exceeding the directed range. In conclusion, the periodontal tactile input does not uniquely increase PFC activity. However, increased CBF in the PFC due to the periodontal tactile input in the posterior region requires existing attention behavior function in the PFC.

Periodontal tactile input activates the prefrontal cortex.

The prefrontal cortex (PFC) plays a role in complex cognitive behavioural planning, decision-making, and social behaviours. However, the effects of sensory integration during motor tasks on PFC activation have not been studied to date. Therefore, we investigated the effect of peripheral sensory information and external information on PFC activation using functional near-infrared spectroscopy (fNIRS). Cerebral blood flow (CBF) was increased around bilateral Brodmann areas 46 and 10 during visual and auditory information integration during an occlusal force (biting) task. After local anesthesia, CBF values were significantly decreased, but occlusal force was similar. In conclusion, the effects of peripheral sensory information from the periodontal ligament and external information have minimal impacts on occlusal force maintenance but are important for PFC activation.

End points and assessments in esthetic dental treatment.

PURPOSE: There are two key considerations for successful esthetic dental treatments. This article systematically describes the two key considerations: the end points of esthetic dental treatments and assessments of esthetic outcomes, which are also important for acquiring clinical skill in esthetic dental treatments. STUDY SELECTION: The end point and assessment of esthetic dental treatment were discussed through literature reviews and clinical practices. RESULTS: Before designing a treatment plan, the end point of dental treatment should be established. The section entitled "End point of esthetic dental treatment" discusses treatments for maxillary anterior teeth and the restoration of facial profile with prostheses. The process of assessing treatment outcomes entitled "Assessments of esthetic dental treatment" discusses objective and subjective evaluation methods. CONCLUSIONS: Practitioners should reach an agreement regarding desired end points with patients through medical interviews, and continuing improvements and developments of esthetic assessments are required to raise the therapeutic level of esthetic dental treatments.

MiR-494-3p induced by compressive force inhibits cell proliferation in MC3T3-E1 cells.

Mechanical stimuli regulate fundamental cell processes such as proliferation, differentiation, and morphogenesis. We attempted to identify microRNA (miRNA) whose expression is changed during compressive treatment in MC3T3-E1, a pre-osteoblastic cell line. Microarray analysis followed by reverse transcription-quantitative polymerase chain reaction revealed that compressive force at 294 Pa for 24 h in MC3T3-E1 cells increased levels of miR-494-3p, miR-146a-5p, miR-210-3p, and miR-1247-3p. Among these miRNAs, miR-494-3p was found to inhibit cell proliferation in MC3T3-E1 cells. Furthermore, cells subjected to compressive force showed slower cell growth compared with control cells. Levels of mRNA for fibroblast growth factor receptor 2 (FGFR2) and Rho-associated coiled-coil kinase 1 (ROCK1), which were predicted to be targets of miR-494-3p, were decreased by compressive force or overexpression of miR-494-3p mimics in MC3T3-E1 cells. Furthermore, binding sites of miR-494-3p within 3'-untranslated regions of Fgfr2 and Rock1 were determined using luciferase reporter assay. In conclusion, compressive force affected expressions of several miRNAs including miR-494-3p in MC3T3-E1 cells. Compressive force might inhibit cell proliferation in osteoblasts by up-regulating miR-494-3p followed by FGFR2 and ROCK1 gene repressions.

Do sensation differences exist between dental implants and natural teeth?: a meta-analysis.

OBJECTIVE: The purpose of this systematic review was to survey evidence pertaining to the sensation differences between natural teeth and osseointegrated dental implants. MATERIAL AND METHODS: Using the MEDLINE (online PubMed) database, Cochrane Library, and Scientific Citation index, we performed a systematic search of articles. We used the following search terms: "perception or sensation and dental implant." The systematic review of the extracted articles was performed to see the sensation differences between natural teeth and dental implants. RESULTS: A total of six studies on oral sensation, "tactile sensibility," and "thickness discrimination" were included in the meta-analysis. As to the "tactile sensibility", all studies indicated the threshold levels of the implants were about 4-20 times higher than that of natural teeth. The tactile sensibility of an implant was significantly higher than that of a natural tooth, with an standardized mean difference (SMD) of 8.3619 (95% CI, 6.3920-10.3317) and a P < 0.0001. As to the "thickness discrimination", all studies indicated the threshold levels of implants were about 1.2-2.3 times higher than that of natural teeth. The thickness discrimination was significantly higher than that of natural teeth with an SMD of 1.2368 (95% CI, 0.8699-1.6038) and a P < 0.0001. CONCLUSION: This meta-analysis suggested that both tactile sensibility and thickness discrimination thresholds of implants were significantly higher than those of natural teeth. This meta-analysis reconfirms that sensation differences between dental implants and natural teeth exist.