The Evaluation Of The Orthodontic Treatment Outcomes With Different Molar Extraction Patterns

Background: With the growth of economic and cultural level,the demand for malocclusion orthodontics is no longer limited to teenagers,and more and more adults also have the command for orthodontic treatment.And adult teeth are usually more complicated,often accompanied by multiple dental caries,dental defects and other problems.In the process of orthodontic treatment,there are not a few molars that are damaged or missing.Based on the principle of preserving healthy teeth,More and more attention has been paid to the orthodontic methods of extraction of molars.The dental caries rate of mandibular first molars is the highest in all teeth.The process of treatment and repair of large area caries is complicated and the effect is not good.Due to the complexity of the anatomical structure of the mandibular first molar,As a result,severe caries often occur earlier,leading to serious damage to the crown of the first molar,and even to the pulp and periapical tissue.In orthodontic treatment,most of the cases need to be removed.However,most of the cases involved extraction of premolars for treatment.However,many of them often encountered problems in the design of tooth extraction.In addition,maxillary molars,especially second molars,were also found to have severe caries and ectopic eruption.Severe torsion,crowding,etc.,or excessive buccal tilt can lead to nonfunctioning.A great deal of literature has shown that the extraction of mandibular first molars can achieve better results,however,What is the effect of extraction of maxillary molars or simultaneous extraction of maxillary molars? Maxillary extraction molars,maxillary sinus affect its closure space? What about the parallelism of the root on both sides of the gap? This requires some objective criteria to evaluate.Objective: OGS index was used to evaluate the effect of extraction of unilateral and bilateral molars on malocclusion and to explore the relationship between the removal of the molar and the occlusion establishment of the third molar,in order to provide reference for orthodontists to choose extraction methods.Methods: A total of 40 patients(20 males and 20 females)were randomly selected from the Department of Stomatology of the second affiliated Hospital of Guangzhou Medical University in the past ten years.According to the different extraction methods,they were divided into unilateral molar extraction group and bilateral molar extraction group.A total of 65 molars were extracted,with an average age of 22.33±1.03 years old.All the subjects were treated with MBT straight wire arch technique.Proper use of class II or III class elastics intermaxillary traction treatment,the orthodontic process is successful.Collect casts of all patients before and after treatment and the panoramic radiographs.According to the objective evaluation system of ABO(Objective Grading System),the casts and the panoramic radiographs were measured.Results: 1.Both bilateral molar extraction group and unilateral molar extraction group had significant improvement before and after orthodontic treatment.The total score of ABO-OGS in the bilateral molar extraction group was decreased by 29.10±15.59,and the total score of ABO-OGS in the unilateral molar group was decreased by 21.00±16.06.The difference between the two groups was statistically significant(P<0.001).2.The alignment,buccolingual inclination,occlusal relationship and overjet of the two groups before and after orthodontic treatment were all significantly improved,and the difference between pretreatment and posttreatment was statistically significant(p<0.01);For the posterior teeth alignment and root angulation,the improvement of the bilateral molar extraction group was more obvious than that of the unilateral group.In terms of occlusal contact,the two groups of ABO-OGS increased,and there was a statistically significant difference(P<0.001).3.Comparison of results after treatment in the two groups: There were no statistically significant differences between the two groups except for the marginal ridges height.The proportion of posterior teeth alignment,the marginal ridges height,and occlusal contact was the highest in the total score,while the anterior teeth alignment and interproximal contacts were the lowest among all single criteria.4.In all cases,15%(6 cases)were passed according to the ABO-OGS certification criteria,and the potential rate of pass was 62.5%(25 cases).5.The course of treatment for removal of molars was longer.The average course of treatment for the unilateral molar extraction group was 30±7.88 months,and the duration of treatment for the bilateral molar extraction group was longer,with an average of 37±9.60 months.A statistically significant difference between the two groups of treatment time was found(P<0.05).Conclusion: 1.Two different protocols of molar extraction can achieve satisfactory treatment outcomes,with the potential of clinical evaluation through ABO-OGS.2.Extraction of molars can effectively relieve the crowd,improve the buccolingual inclination and overjet,which may lead to bad occlusal contact and the marginal ridges height.The OGS score seemed to be greatly influenced by posterior teeth alignment,the marginal ridges height and the occlusal contact,and the interproximal contact was less related to the score.3.Close longer extraction space,eruption of third molars,and occlusal establishment increase the duration of extraction and removal of molars,but avoid root canal treatment and denture restoration,retain healthy teeth,and extend dentition life.