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A case of distal horizontal impaction of right mandibular first molar

Impacted teeth refer to the teeth that can only partially erupt or completely fail to erupt due to the obstruction of adjacent teeth, bone or soft tissue, and can not erupt in the future. impacted teeth often occur in the upper and lower third molars and maxillary canines. The first molar impaction is rare, especially the first molar distal horizontal impaction is more rare A case of horizontal impaction of the first molar of the right mandible was found in the Stomatological Hospital Affiliated to Nanchang University 1. Case report…

Impacted teeth refer to the teeth that can only partially erupt or completely fail to erupt due to the obstruction of adjacent teeth, bone or soft tissue, and can not erupt in the future.

impacted teeth often occur in the upper and lower third molars and maxillary canines. The first molar impaction is rare, especially the first molar distal horizontal impaction is more rare A case of horizontal impaction of the first molar of the right mandible was found in the Stomatological Hospital Affiliated to Nanchang University

1. Case report

A 10-year-old male, who was admitted to the hospital in July 2016, had no history of orthodontic treatment, tooth extraction and systemic diseases. There was no similar deformity in the family members. The intraoral images of

patients before treatment are shown in Figure 1.

A case of distal horizontal impaction of right mandibular first molar

1 oral image before treatment.

A: upper maxillofacial image; B: mandibular face image; C: right side image; D: frontal image; E: left side image.

Clinical examination: mixed dentition, neutral relationship of left molars, shallow overburden of anterior teeth, inversion of right lateral incisors, normal eruption of mandibular permanent incisors and left mandibular first molars, bilateral deciduous canines have not fallen off, the remaining mandibular teeth have not been found, and the mucosal color is normal (Fig. 1).

Panoramic film and cone beam computed tomography (CBCT) three-dimensional reconstruction images showed that 46 tooth germs existed, the crown was distally oriented, and the long axis of tooth was nearly parallel to the lower edge of mandible. The development of distal root was about 2 / 3 of the root length, and the development of mesial root was about 1 / 2 of the root length and slightly bent downward. The mesial root was closely related to 45 teeth, and the rest of mandibular tooth germs were normal (Fig. 2 and Fig. 3)

A case of distal horizontal impaction of right mandibular first molar

2 panorama before treatment

A case of distal horizontal impaction of right mandibular first molar

3 three dimensional reconstruction of CBCT before treatment

After comprehensive analysis and considering the wishes of the patients, the treatment plan of fenestration orthodontics was formulated. 45 teeth that had not yet erupted were extracted to provide space for 46 teeth. 36, 73, 32, 31, 42, 41 and 83 teeth were connected as a whole by casting plate to provide anchorage for traction of 46 teeth (Fig. 4).

A case of distal horizontal impaction of right mandibular first molar

4 the image of orthodontic appliance in mouth.

A: right side image; B: frontal image; C: left side image; D: mandibular face image.

The cast plate was bonded to the mandible with glass ionomer. The rubber chain was connected to the lingual buckle of 46 teeth through the traction hook in the distal of 83 teeth. The rubber chain produced a clockwise rotation force on 46 teeth during the traction of the rubber chain. The 46 teeth rotated clockwise (Fig. 5 and 6) during the operation of

After 5 months of treatment, 46 teeth had obvious clockwise rotation and were basically upright (Fig. 7). At this time, the bilateral deciduous canines fell off and the mandibular casting plate could not be retained. Therefore, the appliance was removed for observation and follow-up. After the other teeth erupted in the later stage, complete fixed orthodontic treatment was performed

A case of distal horizontal impaction of right mandibular first molar

5 intraoral images after 1 month of treatment.

A: right side image; B: positive image; C: left side image; D: mandibular face image.

A case of distal horizontal impaction of right mandibular first molar

Figure 6 panoramic film of 1 month treatment

A case of distal horizontal impaction of right mandibular first molar

Figure 7 panoramic film of 5 months treatment

2. Discussion

The first mandibular molar usually erupts at the age of 6-7 years. At this time, the second molar has not yet erupted, so the eruption space is sufficient and there is no resistance of deciduous teeth above the first molar, so the impaction rate of the first molar is about 0.01% The first molar impaction was divided into vertical, mesial, distal, horizontal and buccolingual positions. Among them, 62.5% were vertical impaction, 19.5% were mesial impaction, 8.5% were horizontal impaction, 6% were distal impaction and 4% were buccolingual impaction

This case is a case of horizontal impaction of the first molar in the right mandible. It is rare that the crown is distally oriented and the root is mesial. The diagnosis and localization of impacted teeth are very important in clinical practice. At present, apical radiographs, panoramic films and CBCT are used to diagnose impacted teeth. The first two images are two-dimensional images, which have the limitations of image distortion and overlap CBCT provides the three-dimensional image information of impacted teeth, through which the position and shape of impacted teeth and the position relationship between impacted teeth and adjacent teeth can be clearly determined.

therefore, the traction direction of impacted teeth can be determined by CBCT

The causes of the first permanent molar impaction have not been determined yet. The possible causes are local factors and systemic factors; 3) The results showed that the resistance of soft tissue was too high, and the crown resistance was too high due to scar and other reasons, resulting in tooth impaction; 4) ectopic tooth germ; 5) tooth eruption path change

The main systemic factors are as follows: 1) genetic factors; 2; 2)

this case has no genetic history, systemic disease history, trauma history, and the gingival color and texture above the molar is normal. Therefore, the cause of impacted molars may be abnormal eruption path. The treatment methods of

impacted molars include the following 1) Surgery assisted eruption: when the impacted molars have normal position, enough eruption space and certain eruption potential, surgical methods can be used to remove the crown soft tissue resistance to make it erupt automatically.

2 2) fenestration orthodontic collaborative treatment: if the impacted molars have abnormal position or bone resistance in the crown, the fenestration orthodontic treatment is needed 3) Orthodontics combined with autogenous tooth transplantation: for the teeth whose transverse position, inversion or traction direction are blocked, the impacted teeth or other normal teeth can be transplanted to the edentulous area by surgical means.

4) if the impacted teeth have short root, abnormal crown and root morphology, and root bone adhesion, the impacted teeth can be removed The shape and position of impacted teeth, the position relationship of adjacent teeth and the wishes of patients should be taken into consideration

In this case, 46 teeth were impacted horizontally. It was difficult for the impacted teeth to erupt automatically by surgical operation Considering that the root development of 46 impacted teeth in this case is fair, and the apical foramen are not completely closed, there is still a certain development potential. Therefore, 45 teeth which have not yet sprouted and have relatively weak function were extracted to provide space for 46 teeth to be vertical, and the 46 teeth with relatively strong function were retained through window opening and orthodontic treatment

original source:

Sun Chuanxi, Li Zhihua, Zhou Ziqi. A case of distal horizontal impaction of right mandibular first molar [J]. West China Journal of Stomatology, 2019 (01): 106-108

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