Study On The Pain Threshold Of Periodontal Ligament Pressure

Part 1Test-retest reliability of a new technique with pressure algometry applied to teeth in healthy Chinese individuals Objectives:Algometry and pressure pain threshold(PPT)have been shown to be a useful method to obtain measures of mechanical pain sensitivity from deep tissues.However,clinical methods for measuring mechanical allodynia in teeth have not been reported.The aim of this study was to assess the reliability of PPTs in the periodontal ligament by direct stimulation of the teeth in healthy Chinese participants.Methods:Twenty healthy young adults(ten males and ten females)participated.PPTs were measured at six teeth(maxillary and mandibular incisors,canines and first premolars on either the left or right side)and in two directions(lateral and vertical),the pressure was increased steadily at a rate of 30 kPa/s.The tests included three consecutive trials in two separate sessions conducted by one examiner on the first day.After 1-3 weeks,an identical protocol was carried out by two examiners,also in two separate sessions.Data were analyzed with reliability tests and three-way analysis of variance(ANOVA)for repeated measures.Results:The PPTs for all teeth,sessions and examiners were stable with no significant differences between repeated measures(P>0.129).The PPTs had excellent reliability with high intra-class coefficients(ICC)across different sessions(ICC:0.871-0.956),days(ICC:0.879-0.951)and examiners(ICC:0.845-0.950).Conclusion:Pressure algometry and PPTs applied to the teeth have excellent intra-and inter-examiner agreement in healthy participants.This method may be proposed as an easy and reliable technique to assess e.g.mechanical allodynia and hyperalgesia in the periodontal ligament associated with endodontic or periodontal conditions and further clinical studies are warranted.Part 2Assessment of periodontal mechano-nociceptive function in healthy Chinese individualsObjectives:The objective of this study was to test a new technique for assessment of periodontal mechano-nociceptive function by direct application of controlled forces to the teeth and quantify site,side and gender differences in healthy individuals.Methods:Twenty healthy young adults(ten males and ten females)participated.A pressure algometer was used to assess pressure pain threshold(PPT)on the maxillary and mandibular incisors,canines and first premolars on the left and the right side from two directions:lateral and vertical,the pressure was increased steadily at a rate of 30 kPa/s.Statistical analysis was performed using analyses of variance(ANOVA)with repeated measures to compare data.Results:There were significant gender differences of PPT for both lateral(Pbuccal=0.007)and vertical(Pocclusal=0.001)directions with lower thresholds in females(higher sensitivity)than in males.A significant site effect(Pbuccal=0.000,Pocclusal=0.000)was observed with less sensitivity at the first premolar compared to the anterior teeth.No significant right-to-left side differences(Pbuccal=0.521,Pocclusal=0.082)were found for the PPTs.There were significant differences between lateral and vertical direction(P<0.001).Conclusion:The different patterns of mechano-nociceptive function in the periodontal ligament in healthy individuals may help for a better understanding of the underlying mechanisms of mechanical allodynia or hyperalgesia in different periodontal disorders.