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We examined the effects of mechanical load on transcripts of a set of cell wall related genes that are implicated in the formation of supporting tissues, by applying a 50 mg strip of aluminum foil to the inflorescence stem of Arabidopsis thaliana, a weight roughly half the fresh weight of the stem. Transcript levels of 12 of the 15 genes examined were increased by load application, as were the levels of some transcription factors that regulate secondary wall formation. These findings support the involvement of a load-sensing system in regulation of supporting tissue formation via transcriptional regulation of cell wall related genes. [ABSTRACT FROM AUTHOR]

Objectives. Edentulous oral mucosa involves different tissue types, various innervation and wound healing process. We hypothesized that pressure pain threshold (PPT) of edentulous oral mucosa varies significantly among different regions. The objective of this study is to examine regional differences and correlations of PPT in edentulous oral mucosa.Methods. Pain threshold (PPT) was measured at 112 sites in 15 edentulous patients using an electric-controlled pressure algometer. PPT mapping was created by the level of PPT, and PPT clustering was undertaken based on the inter-site correlation of PPT.Results. PPT increased from the anterior to posterior alveolus in both maxilla and mandible, but decreased from the anterior palate to the posterior palate. PPT decreased from the ridge crest to the buccal vestibule. The inter-site difference was four fold within the maxilla and 2.4 fold within the mandible. Principal component analysis applied on PPT inter-site correlation matrix revealed that the maxilla and mandible could be differentiated statistically. The maxilla and mandible were divided into three and four clusters, respectively.Conclusion. These results demonstrate that different areas of edentulous oral mucosa have different PPT and that the PPT varies proportionally in selected areas, providing useful diagnostic and therapeutic information in removable prosthodontics and a new opportunity for understanding pain underneath the denture. [Copyright &y& Elsevier]

Once subjected to denture wearing, oral mucosa has to withstand mechanical loads of various levels and durations. However, how this load affects oral mucosal sensitivity is unknown. This study investigated the pressure–pain threshold (PPT) of oral mucosa with or without pre-loading. An electric pressure algometer was developed specifically for measuring the PPT of oral mucosa. Measurements of 10 dentulous maxillae showed that the baseline PPT (BPPT) of the palatal site was 4·9- and 3·7-fold greater than that of the labial or buccal sites, respectively. The PPT of the labial site decreased significantly compared with its BPPT after 2 s–100% BPPT and 5 s–100% BPPT pre-loading. The PPT of the palatal site increased after 5 s–50% BPPT and 5 s–80% BPPT and 0·2 s–100% BPPT and 2 s–100% BPPT pre-loading. The PPT of the buccal site did not change after all levels and durations of pre-loadings tested. These results indicated the disproportionate modulation of oral mucosal PPT following various loads, suggesting that oral mucosa possesses region-specific psychophysical tolerance to mechanical stimuli. [ABSTRACT FROM AUTHOR]

Fundamental knowledge of pain in the oral mucosa is lacking. We determined the validity and reliability of the pressure–pain threshold (PPT) measurement in the oral mucosa using a newly developed hand-held pressure algometer. Ten dentulous subjects were recruited, and the PPT was measured at the bilateral buccal (on the attached gingiva apical to the midline of the upper first premolars, 3 mm from the mucogingival junction) and the palatal sites (mid-point between the bilateral upper first molars). The PPT linearly increased with an increase in load-rate (P < 0·0001). The PPT yielded a high intra-individual stability both for the same-day consecutive trials and weekly sessions. The palatal site revealed a 4- to 4·65-fold greater PPT than the buccal sites (Bonferroni, P < 0·0001), whereas no difference was found between the bilateral buccal sites (P =0·663). Despite a great interindividual variation in the PPT, significant intra-individual correlations were found among the measurement sites. This suggested differences in individual sensitivity to pain in the oral mucosa, which may determine overall pain sensation specific to an individual. A pressure algometer described herein reliably assessed the PPT in the oral mucosa and sensitively discriminated PPT differences at different sites and at different load-rates, suggest-ing the reliability and validity of PPT measure-ments in the oral mucosa for clinical and research investigations. [ABSTRACT FROM AUTHOR]