The Effect Of Orthodontic Force On Pulp Vitality Evaluated With Pulse Oximetry

Objective:1.To evaluate the relationship between the levels of saturation ofperipheral oxygen(SpO2) in the teeth and in the index finger of the patient by checkingthe SpO2values of the dental pulp in maxillary canine teeth.2.To study the effect oforthodontic force on the pulp by assessing pulpal blood circulation and oxygen saturationof maxillary canines under the distal150g orthodontic force using pulse oximetry.Methods:48patients of processed maxillas who need orthodontic treatment,24males,24females,aged12to16years,were examined.The relevance between the SpO2levels in thecanines and in the index fingers was investigated by measuring the SpO2values in96healthy maxillary canines and in the index finger of48patients using mindray PM-60pulse oximeter with separate oxygen sensor,and the SpO2levels of maxillary canineswere measured before and at1d,7d,14d,21d,28d after the150g orthodontic force wasapplied on them.All teeth were proved to be healthy by a thermal test with dry ice andthen subjected to a vitality test with pulse oximetry. Results:1. Mean oxygen values inthe index finger of48patients were（98.25±0.91）%.Mean oxygen values in the left andright maxillary canines were（83.73±2.03）%and（83.81±2.57）%, respectively. Therewas no significant statistical difference in the SpO2values between the left and rightmaxillary canines（P>0.05）.There was a statistically significant difference between theSpO2levels obtained from both the index fingers and the left and right canine teeth（P<0.001）,but there were no significant statistical correlations（P>0.05）.The levels ofSpO2of healthy maxillary canine were（83.77±2.30）%.2. There was a statisticallysignificant difference for the levels of SpO2among times（F=349.859,P<0.001）.Themultiple comparisons indicated that there’s a statistically significant difference in theoxygen levels between each time point except that among before, at1d and28d afterorthodontic force application.The SpO2levels after1d of orthodontic force decreased,and at7d decreased to the least,and then gradually increased,at last, at28d returned to thelevel before the force was applied. Conclusion:1.Pulse oximetry determined consistentlythe level of SpO2of the pulp in the left and right healthy maxillary canine teeth,thereforeit is an effective,objective method of evaluating dental pulp vitality.2.The application of150g orthodontic distal force could cause a temporary change of the SpO2levels of thedental pulp in maxillary canine teeth,but it’s reversible and followed by recovery at28dafter orthodontic force application.The results indicate that the measurement techniqueshown in this study could detect SpO2change produced by continuous orthodontic forceapplication.