Application Of Laser Doppler Flowmetry In The Evaluation Of The Trend Of Pulp Vitality Of Traumatic Young Permanent Teeth

Dental trauma is a common and frequently occurring disease in the field of dental treatment and it is especially common in children.Young permanent teeth trauma accounts for 50-70% of the permanent traumatic injury and plays on the role of being the important factor that caused children’s teeth to be defected or even missed.The key to its diagnosis and treatment is to retain vital pulp for traumatic young permanent teeth as much as possible to promote the continued development of the roots.However,a scientific and rational diagnosis and treatment program for traumatic young permanent teeth depends on the early diagnosis of its pulp state.Therefore,it is of great significance to explore a new,objective,accurate and reliable detection method of pulp vitality for the diagnosis and treatment of traumatic young permanent teeth because the traditional dental pulp sensory test methods are difficult to be used for young permanent teeth and the subjective feedback of children is often inaccurate.Laser-Doppler flowmetry(LDF)is a painless,non-invasive and objective method for the detection of dental pulp vitality.The detection object is the change of the pulpal blood flow(PBF),which is objective and accurate.The advantages can be applied to the detection of dental pulp vitality of young permanent teeth.This study aimed to solve the problem of judging the state of pulp after tooth trauma among children according to the status of dental pulp testing at home and abroad.The normal reference range of PBF and related factors of laser-Doppler dental pulp blood flow among anterior teeth in different age groups was summarized and analyzed by collecting the PBF of normal group.Several laser-Doppler tests of different types of dental trauma cases was collected combining with clinical and imaging findings that aimed to explore the trend of PBF of the three trauma groups including concussion,subluxation,and uncomplicated crown fracture and calculate its clinical compliance rate thereby to validate whether it would have a high sensitivity and specificity.A reliable means of detection for the early and accurate diagnosis of dental pulp of young permanent teeth with trauma and a reference for formulating or adjusting the diagnosis and treatment plan and long-term prognosis were provided.Part One: To detect the clinical reference value of anterior teeth PBF in adolescents of different age groups by LDF.Aim: To statistically analyze and calculate the range of physiological clinical reference range of the PBF values of maxillary central incisor and lateral incisors through collecting the dates from healthy volunteers aged 7 to 12 years and more or less 20 years old.Methods: The standard of inclusion and exclusion were made according to the working principle of LDF and then the amount of sample size required for the experiment was estimated.A great amount of volunteers were recruited after the approval by the Ethical Committee of Oral Medicine Hospital of the Air Force Military Medical University and an informed consent was signed.All data of PBF was collected by the standard operating procedures and then estimated interval used SPSS 19.0 in order to calculate the clinical reference range.The related factor which may impact the PBF was discussed through chi-square test and randomized block analysis.Results: The required sample size for young people aged more or less 20 years old was calculated as 385 and for children aged 7-12 was 584 according to the result of pre-experimenting.400 students(250 males and 150 females)who meet the inclusion criteria were recruited into this study and the requirements of the experimental sample size were met by recruiting undergraduates of the Air Force military medical university.682 preschool children(358 males and 324 females)were enrolled in the study.1364 cases of incisors and 1180 cases of lateral incisors were collected to meet the needs of sample size testing and the results were valid.The clinical reference value of the anterior teeth PBF in the 20-year-old youth population in this study was calculated as: Male: The tooth of 12 was 8.85 ± 1.48,the tooth of 11 was 9.43 ± 1.53,the tooth of 21 was 9.38 ± 1.51 and the tooth of 22 was 8.84 ± 1.47;Female: the tooth of 12 was 9.63 ± 1.47,the tooth of 11 was 10.14 ± 1.58,the tooth of 21 was 10.23 ± 1.58 and the tooth of 22 was 9.68 ± 1.335.There was a statistically significance between male and female 12-22 teeth(P < 0.05)and there was also a statistically significance between central incisors and lateral incisors whether male or female(P < 0.05),however,there was no statistically significant correlation between PBF and age(P > 0.05).The range of PBF clinical reference value of anterior teeth of children aged 7-12 was: 12 teeth: 10.40 ± 1.90,11 teeth: 8.56 ± 1.50,21 teeth: 8.97 ± 1.49,22 teeth: 10.42 ± 1.91.There was no statistically significance between genders in this learning(P > 0.05).The PBF of the central incisor was lower than that of the lateral incisor and the difference was statistically significant(P < 0.001).There was a statistically significant correlation with age changes(P < 0.05).Conclusion: There was a statistically significant correlation between the PBF and gender in the 20-year-old youth group by LDF(P <0.05).There was a slight difference in the normal reference range between men and women that the female had a slightly higher PBF than the male.There was a statistically significance between the central and lateral incisors(P <0.05),but no statistically significant correlation with ages(P> 0.05)was found.There was no statistically significance between male and female in the age group of 7-12 years old school-age children(P> 0.05).There was a statistically significance between the central incisors and the lateral incisors(P <0.05)that the lateral incisors had slightly higher PBF than the central incisors.There was a statistically significant correlation with ages(P <0.05)that shown a trend of gradual increasing and then being stable or slightly decreasing with the gradual increase of age.Part Two: To explore the clinical coincidence rate of the traumatic teeth PBF detected by LDFAim: The clinical compliance rate was aimed to be calculated according to the number of true positive and true negative statistics by using LDF to detect the PBF of the uncomplicated crown fracture,concussion and dislocation combined with clinical and imaging findings.Meanwhile,whether LDF had higher sensitivity(Se)and specificity(Sp)in the detection of traumatic dental PBF would be validated.Methods: The criteria of inclusion and exclusion of this study was made according to the Andreasen classification method combined with the principle of LDF test.The dental PBF of traumatic teeth was collected from the clinical children cases who suffered dental trauma according to the LDF standard operating procedures after the informed consent had been signed yet.The case data was collected according to the diagnostic test and standard diagnostic four grid table.The corresponding positive and negative diagnostic criteria were developed combining with the clinical and imaging performance.The positive standard was made up with the situation that the detected PBF was lower than the normal reference range that had obtained in Part I;the clinical examination showed that situation such as percussion pain,loose or discoloration and the imaging findings showed an apical shadow;diagnostic pulp-opening which prompted the pulp to be necrotic or inactivated.The negative standard included that the PBF stayed in the normal reference range and the clinical examination of the traumatic teeth showed no obvious percussion pain,loose or discoloration and there was no significant abnormalities in imaging examination and no pathological changes were observed in the long-term follow-up.Results: The clinical coincidence rate was 91.81% and the specificity and sensitivity were respectively 99.76% and 41.54% in the detection of PBF with uncomplicated crown fracture group by LDF.The clinical coincidence rate was 90.23% and the specificity and sensitivity were respectively100% and 7.14% in the group of concussion.The clinical coincidence rate was 87.77% and the specificity and sensitivity were respectively100% and 47.17% in the group of dislocation.There was a high specificity but a relatively low sensitivity in the detection of traumatic dental PBF with LDF and a number of possible factors such as early vascular contusion,post-traumatic root bone adhesion,root canal calcification,root fracture,feed the transmission factor or dental fluorosis,etc might result in a relatively high rate of false positives while such cases could mostly be ruled out according to the clinical and imaging examinations.The clinical compliance rate was as high as 90.42% in the detection of traumatic teeth PBF used by LDF which could provide a more reliable theoretical basis for the diagnosis and treatment of traumatic teeth.Conclusion: A high clinical compliance rate for the PBF of trauma teeth detected by LDF was proved and the false positive situation was more common in the early of the trauma especially in the type of periodontal support tissue trauma which may be related to its apical vascular reversible contusion in addition to the high possibility of root adhesions or root canal calcification in the long-term follow-up.Furthermore,the conservative concept of treatment also increases the probability of false positives to some extent.Overall,LDF could provide a more accurate basis for judging the state of dental pulp of traumatic teeth(especially in young permanent teeth trauma)and could be widely used in many fields of dental treatment.Part Three: Research on the trend of PBF in the treatment of uncomplicated crown fracture,concussion and subluxation with LDFAim: The PBF of the uncomplicated crown fracture,concussion and subluxation teeth in accordance with the Andreasen classification were measured and collected to do some statistical analysis to research the trend of the prognosis and explore the related factors.Methods: The criteria of inclusion and exclusion of this study was made according to the Andreasen classification method combined with the principle of LDF test.The dental PBF of traumatic teeth was collected from the clinical children cases who suffered dental trauma according to the LDF standard operating procedures after the informed consent had been signed yet.The patients were scheduled to be reviewed after the injury of the injured tooth for 1 month,3 months,6 months and 12 months and might be shorten the review period if there was any abnormality.The test results was statistically analyzed by using SPSS 19.0,respectively,to obtain the trend of PBF of uncomplicated crown fracture teeth after the indirect dental pulp treatment or the treatment of direct filling and the concussion and subluxation teeth and also to analyze the factors that led to the trend.Results: The early PBF value of the tooth was higher than the normal group in the uncomplicated crown fracture group which showed the state of the marrow cavity congestion that gradually decreased to the normal range and tended to be stable after 3 to 6 months follow-up.A small part of the early PBF was little lower than normal values which a certain degree of loosening was often accompanied and gradually rose to or slightly below the normal range and tended to be stable in the follow-up process.The trend of PBF in capping group and direct filling group was basically same,but the incidence of dental pulp necrosis was higher after direct filling in the long-term follow-up and the prognosis was worse than that of capping.Pulp necrosis often occurred more than half a year and even was found within 1 to 2 years after trauma,so the traumatic teeth should be followed up for at least 1 to 2 years.The prevalence of PBF in different age groups was consistent with the overall trend.The overall trend of the PBF of the concussion teeth was relatively stable while the PBF was slightly lower in the early trauma and the prevalence trend of different ages of the teeth was basically the same.The level of PBF in subluxation teeth was low at early stage of injury which was common within 1 month after trauma that would gradually increase to the normal range with the extension of follow-up period,meanwhile,some of the patients suffered from dental pulp necrosis.The overall trend was a gradual increase and gradually stabilized in 3 to 6 months after injury,while the PBF of some teeth showed a decreasing trend in the long-term follow-up.Conclusion: The tendency of PBF changes with time in the uncomplicated crown fracture group was slightly higher than the normal range in the early stage,and gradually decreased to the normal range after 3 to 6 months of follow-up,and the trend of PBF at different ages was basically the same as the whole.The rate of dental pulp necrosis after direct filling was relatively high and the long-term prognosis was worse than that of capping.The patients should be asked to pay more attention to the postoperative follow-up of PBF in order to make effective intervention for early detection of pathological changes.With the extension of follow-up,most of the PBF in the group of concussion and subluxation teeth gradually returned to normal and tended to be stable.The concussion had little effect on dental pulp blood flow and the overall trend was stable.The PBF of the subluxation teeth was a bit lower in the early trauma and the probability of occurrence of dental pulp necrosis was relatively high.So,it is significant to make effectively fixed early for the teeth with obvious loosening of the subluxation.