Volume 30 Issue 4 Article 6

2020

Management of Tipped and Impacted Mandibular Second Molars

Jung-Chun Yeh Orthodontic Department, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Chien-Wei Chao Orthodontic Department, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Yu-Tin Wu Orthodontic Department, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Chih-Chen Chou School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

Chia-Tze Kao Orthodontic Department, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan, [email protected]

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Recommended Citation Yeh, Jung-Chun; Chao, Chien-Wei; Wu, Yu-Tin; Chou, Chih-Chen; and Kao, Chia-Tze (2020) "Management of Tipped and Impacted Mandibular Second Molars," Taiwanese Journal of Orthodontics: Vol. 30 : Iss. 4 , Article 6. DOI: 10.30036/TJO.201812_30(4).0006 Available at: https://www.tjo.org.tw/tjo/vol30/iss4/6

This Case Report is brought to you for free and open access by Taiwanese Journal of Orthodontics. It has been accepted for inclusion in Taiwanese Journal of Orthodontics by an authorized editor of Taiwanese Journal of Orthodontics. Case Report

Management of Tipped and Impacted Mandibular Second Molars

1,2 1,2 1,2 2 1,2 Jung-Chun Yeh, Chien-Wei Chao, Yu-Tin Wu, Chih-Chen Chou, Chia-Tze Kao 1 Orthodontic Department, Chung Shan Medical University Hospital, Taichung, Taiwan 2 School of Dentistry, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan

This is a 12Y11M old girl with mesial tipping of left and right mandibular second molars. The chief compliant was crowding of the teeth. The clinical examination revealed crowding of lower anterior teeth, 13, 23 block out and 47, 37 mesial tipping. The diagnosis was Angle Class I malocclusion with lower anterior crowding st and 37, 47 mesial tipping. The treatment plan was four 1 extraction. The treatment goal was to align anterior teeth and upright 37, 47. Two different uprighting spring were applied, one was a hand-bending lever arm appliance on the right second , and the other was a prefabricated upright spring on the left second molar. Total treatment duration was 4 months for the 37 and 47 uprighting. Correction of the mesial tipped mandibular molars is important for better oral hygiene care, improving occlusion and chewing function, and facilitating the prosthodontic rehabilitation. The aim of this case report was to interpret etiology of the tipped mandibular molars, and to enumerate the treatment options for uprighting of the mesial tipped mandibular molars. (Taiwanese Journal of Orthodontics. 30(4): 238-246, 2018)

Keywords: tipped mandibular second molar; molar uprighting.

teeth occur most commonly in third molars. Impaction INTRODUCTION of mandibular second molars are rare with an incidence 3,4 Mesial tipping of mandibular second molars are of 0–2.3%. Fu et al in 2002, reported an incidence caused by the following factors, including: (1) loss of the of 0.65% of mandibular second molars impaction in 2 after eruption of mandibular second Taiwan. Impacted second molars are commonly mesially 5-7 molars; (2) early loss of the mandibular first molar before inclined. The etiology of impaction is related to some eruption of mandibular second molars at a young age, disturbance of physiological mandibular growth and and without placing any space maintainer; (3) mandibular development. The space for second permanent molars is 1 second molar impaction with mesioangulation. obtained by resorption of the bone at the anterior border Impaction of tooth was defined as failure of tooth of the mandibular ramus and mesial migration of the eruption caused by a physical obstacle in the eruption first molar into the leeway space. The tooth bud of the 2 path or the abnormal position of the tooth. Impaction second permanent molar develops with some mesial

Received: July 20, 2018 Revised: December 13, 2018 Accepted: December 18, 2018 Reprints and correspondence to: Dr. Chia-Tze Kao, Department of Dentistry, Chung Shan Medical University, Taichung, Taiwan No.110, Sec. 1, Jianguo N. Rd., South Dist., Taichung City 402, Taiwan Tel: +886-4-24718668 Fax: +886-4-24759065 E-mail: [email protected]

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6 axial inclination and the ability for natural self-correction permanent molar roots is still undergoing development. 6,8 manifests as the remodeling changes occur. Inadequate growth may lead to disturbances of this natural CASE REPORT process and cause the impaction which was mainly 6,9 This is a 12Y11M female with both mesial tipped associated with an arch length deficiency. The second left and right mandibular second molars. She came to molar needs the distal root of the first molar as the guide our hospital with her parents for orthodontic consultation for proper eruption .Therefore, excess space between the developing second molar and first molar may also result in due to crowding of teeth. She denied any major systemic 6,10 impaction. Sometimes the second molar gets impacted disease and drug allergy. She had received dental care at spontaneously, which is probably related to the third local dental clinics, and she has good oral hygiene. 6,11 molar position. The findings of clinical examination are as On the other hands, impaction of lower second followings: (1) extraoral findings: convex profile with molars also develop during orthodontic treatment, when: facial symmetry, normal facial height proportion, no lip (1) banding on 36 or 46, that may cause unerupted 37 and incompetence, no mentalis muscle strain, no occlusal 47, progressively tipping mesially instead of erupting; (2) canting, nasolabial angle 98°, upper show is 50%; distalize 36,46 in mixed dentition also increases risk of (2) intraoral findings: Class I molar relationship on both 1 37, 47 impaction; (3) lip bumper or lingual arch therapy side, lower midline shift to left 2.5 mm, overjet 2.5 mm, that may prevent the mesial shift of the first permanent overbite 2 mm, crowding of upper and lower anterior 6 molars. teeth, 13, 23 blocked out and 47, 37 are mesial tipped The best time to treat impacted mandibular molars impaction. Figure 1 presents the initial models of this is between 11 and 14 years of age, when the second patient.

Figure 1. Initial models and photographs. The mandible right and left side second molars were mesially tipped.

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The panoramic film showed 47, 37 impaction with uprighting spring to correct mesial tipped and impacted mesial tipping. The cephalometric analysis demonstrated 37, 47. that the SNA=86°, SNB=83°, ANB=3°, U1-SN=115°, The orthodontic treatment started with full mouth L1-MP= 105°, U1-L1=111°, upper lip to E-line was 1.5 0.022x0.028 slot pre-adjusted OPA-K bracket system. mm, lower lip to E-line 4 mm (Figure 4a, Table 1). Space After 7 months of preliminary alignment and leveling, analysis demonstrated space discrepancy of 3 mm in the 16x22 stainless steel wire was inserted in lower arch. In upper arch, and -4 mm in the lower arch. the same time 17x25 TMA wire-bended lever arm was ® applied on 47, and a prefabricated Memory Titanol Diagnosis and treatment upright spring was applied on 37. The memory Titanol The diagnosis was dental and skeletal Class I upright spring consist of a 16x22 Ni-Ti wire on the malocclusion with bimaxillary protrusion, upper and posterior part that is connected by means of a climbable lower anterior crowding and 37, 47 are mesial tipped tube to a 17x22 stainless steel wire on the anterior part impaction. The treatment goal is to upright the mesial (Figure 2a). After placing the auxiliary uprighting springs tipped and impacted 37, 47, to relieve crowding of upper on both side for 4 months, 37 and 47 were uprighted. and lower anterior teeth, to retract proclined upper and Figure 2b presented the progress of treatment. We can also lower . The treatment plan was four 1st premolars see the result of 37, 47 well uprighted in the panoramic extraction due to crowding of both arches, and using the film (Figure 3b).

Table 1. Cephalometric analysis in initial and treatment progress stage.

Measurement Norm Pre-Tx Progress

Skeletal

SNA (°) 79.8 ~ 83.2° 86° 86.5°

SNB (°) 75.7 ~ 78.7° 83° 84°

ANB (°) 3.2 ~ 5° 3° 1.5°

SN-MP (°) 33.8 ~ 38.4° 29° 27°

Dental

U1 to SN (°) 4.3 ~ 8.1 4.5 1

U1 -NA (mm) 103.85 ~ 108.75° 115° 110°

L1 to MP (°) 5.4 ~ 10.2 5.5 4.5

L1 -NB (mm) 93.4 ~ 99.2° 105° 95°

Soft tissue

U lip - E line (mm) 0.7 ~ 3.1 1.5 0

L lip - E line (mm) 0.2 ~ 3.4 4 2

240 Taiwanese Journal of Orthodontics. 2018, Vol. 30. No. 4 10.30036/TJO.201812_30(4).0006 Upright the Tipped Mandibular Second Molars

2a

2b

2c

Figure 2. a , A self-bending lever arm uprighting appliance of 0.017 ×0.0 25 TMA wire was bended and placed on 47 (right). A prefabricated ® Memory Titanol upright spring was placed on 37 (left); b , With auxiliary uprighting springs placing on both side for 4 months, both impacted second molars were uprighted; c , Intraoral photos in finishing and detailing stage.

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3a

3b

3c

Figure 3. a , initial panoramic film; b , progressive panoramic film; c , panoramic film in the finishing stage.

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The patient is still undergoing the final detailing SN=110°, L1-MP= 95°, U1-L1=128°, upper lip to E-line stage of orthodontic treatment. The extraction space of was 0 mm, lower lip to E-line 2mm. Figure 4b showed 14,24,34,44 have been closed, Class I molar relationship is superimposition of the Initial (blue line) and progressive still maintained; proper overjet, overbite and interdigitation (red line) cephalometric tracing. is almost achieved. The mandibular dental midline The patient is still in growth, overall superimposition coincided with maxillary and facial midline (Figure 2c). showed vertical skeletal and soft tissue growth. Maxillary Figure 3c, Figure 4a, right demonstrated the panoramic superimposition presented the upper incisor film and cephalometric film after molar uprighting. lingually tipped 8°, and extruded 1 mm. The upper first Compared to the initial cephalometric film (Figure. 4a, molar mesially moved 4.5 mm. The lower incisor crown left), the mandibular second molars were uprighted. tipped lingually by 6°, retracted 3 mm and intruded 1 mm. The following are initial and progressive cephalometric The lower first molar extruded 2 mm, mesially moved 2.5 analysis (Table 1). The progressive cephalometric analysis mm. The lower second molar uprighted distally by 48°. demonstrated SNA=85°, SNB=84°, ANB=1.5°, U1-

4a

4b

Figure 4. a , initial and progressive cephalometric films; b , superimposition of the initial and progressive cephalometric tracing, overall superimposition (left), maxillary superimposition (right upper), and mandibular superimposition (right lower).

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auxiliary uprighting spring to upright the second molar. DISCUSSION The best choice of the segmental auxiliary spring is 16x22 In order to correct impacted/tipped molars, one M-NiTi wire which provides a light force to align the 1 should tip the tooth posteriorly and then upright it. Use second molars. A sectional cantilever uprighting spring by a pure couple force system with a high moment-to-force using 17x25 beta-Ti (TMA) wire without a helical loop or 6 ratio is to secure a pure rotation of molar uprighting. A 17x25 SS wire with a loop for more springiness, is also 1 long cantilever gives a high moment-to-force ratio, which an option to upright the tipped/impacted molar. Inserted results in a clinical effect that very close to a pure rotation. distal arm of spring into the second molar tube, and the The moment of 800–1500 g/mm has been suggested to uprighting spring is activated by lifting the mesial arm 6,12 rotate a molar. The main effects of cantilever on the and hooking it over a stabilizing wire between the is distal crown tipping and the molar extrusion. A and brackets. 6 long cantilever delivers less extrusion than a shorter one. The uprighting spring is a cantilever which produces Several methods for different severity of the mesial- effects of distal crown tipping and molar extrusion. The tipped impacted mandibular second molars are discussed forces acting on the tipped second molar is of the same as followings: magnitude as, but in opposite direction to the forces acting on the stabilizing wire. Thus, the couple of force would 1. When the second molar is mild tipped and the 6 rotate the second molar distally. There is a commercially first molar is missing. ® available prefabricated Memory Titanol upright Simply use a flexible 17x25 A-NiTi single wire to 1 spring, which has similar mechanics with the traditional complete the necessary uprighting is suggested. Or a uprighting spring for clinical convenience. braided rectangular steal wire could be considered, but 1 There are other methods for molar uprighting: it requires frequent removal and reshaping. During the (1) Miao’s method: use a double or triple push spring process of mandibular molars uprighting, it is essential bended from 18 SS wire, and solder it onto the lingual to remove the occlusal interference to prevent excessive surface of the band of the tipped molar. Activated the tooth mobility and increases treatment duration. spring by compressing the spring to engage the lingual 2. When the second molar is impacted and mild tipped. 13,14 button on the tipped molar. Insert a separator between the second and first molars (2) Kuang’s Method: Molar uprighting with AIPS 1 is suggested. Or a brass wire penetrating beneath the (Anterior Insertion Pushing Spring). AIPS is a double 4 contact point between two teeth could be used. helix push spring, which is made of a 17x25 TMA 3. When the second molar is severe tipped/ impacted. wire. Inserted the mesial segment into the auxiliary An attachment must be bonded to the second tube of the first molar mesially, and engage to the molar. Placing a segmental auxiliary NiTi wire from distal hook over the lingual button on the impacted the auxiliary tube on the first molar to the tube on the molar. Tie the mesial helix with the hook of the 14 second molar is an easier way to upright the second adjacent molar to activate the spring. molar. Using a continuous wire to upright the molar (3) Liaw’s method: a modification of Kuang’s method, will cause side effects on the position and inclination which changed the wire to 16x22 NiTi, without wire 1 14 of the second premolar. Therefore, we may carry out a bending. sectional uprighting spring to generate the effect of distal (4) Richard Bach’s method: Insert a 14x25 CuNiTi wire crown tipping. Use a stiff 19x25 steel wire maintains the between the 2 molars. Followed by bending the wire relationship of the teeth in the anchor segment and an to the occlusal surface of the adjacent first molar and

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22-25 secure the wire over occlusal surface with light cured be alterted. The microorganisms such as B.f, B.g, B.i, composite resin. For open bite cases, this technique A.a, also diminished in the mesial pocket of the mesial 14 22,26,27 should be avoided. tipped molar reporting in the previous studies. (5) Tip back cantilever technique: combined the cantilever and the mechanics similar to Richard Bach’s method CONCLUSION 15 with a 16x22 TMA wire. By using simple biomechanics, one may easily (6) Lin’s method: Use a 14 or 16 Ni-Ti wire and place an 14,16 correct the tipped molars. In this case report showed open coil spring between the tubes of the 2 molars. that the two appliances, hand-bending and prefabricated (7) using a lingual holding arch with distal extension as upright spring, have similar treatment effects. Proper an anchorage is also a treatment option to upright the orthodontic analysis, diagnosis, and treatment planning tipped molars. are important keys to correct the tipping molars. If the 4. In cases of very deeply impacted molars. mandibular first molar was lost after the second molar Inserting a miniscrew over the ascending ramus, may eruption, the space should be maintained by space upright the molar in a short period of time. Surgically maintainer for further fixed bridge or implant prosthesis in 1,28 exposure the impacted molar, bond a button on it, and the future. 1,14 pull it up with elastic chains. Once enough exposure If the patient loss the best timing to maintained the achieved, bond a buccal tube and use a NiTi wire to keep space and the molar already mesial tipped, using the 1,7,14,17 uprighting the impacted molar. The miniscrew uprighting mechanics is suitable for treatment. Uprighting can also be inserted at the area anterior to the impacted the mandibular tipped molars is beneficial for oral hygiene molar and use the mini-screw assisted uprighting spring care, occlusion and chewing function, and the condition 18,19 (MAUS). for prosthodontic rehabilitation as well as quality of life Surgical uprighting and autotransplantation are for the patients. 24,25,26 also discussed in the literature. Generally, surgical methods bring a higher risk of complications, such as REFERENCE 10,20,21 necrosis, ankylosis, or root resorption. In our case, the second molars are mild to moderate 1. Pr offit W, Fields H. Contemporary Orthodontics. St. mesial tipped and impacted. We use a cantilever lever arm Louis, Missouri: Mosby; 2013. pp 544, 627-630. 2. uprighting appliance by a 17x25 TMA wire on the right Fu PS, Wang JC, Wu YM, Huang TK, Chen WC, Tseng YC et al. Impacted mandibular second molars. mandibular second molar, and a prefabricated Memory ® Angle Orthod 2012;82:670-675. Titanol upright spring with 16x22 stainless steel main 3. Grover PS, Lorton L. The incidence of unerupted wire as anterior anchor unit. Both sides of mesial tipped and related clinical cases. Oral Surg and impacted molar were uprighted within four months. Oral Med Oral Pathol 1985;59:420-425. There are several benefits after uprighting of the 4. Cassetta M, Altieri F. The influence of mandibular mesial tipping and/or impaction mandibular molars, third molar germectomy on the treatment time of such as reducing risk of dental caries and periodontal impacted mandibular second molars using brass wire: problems, avoiding adjacent teeth root resorption, and a prospective clinical pilot study. Int J Oral Maxillofac easier prosthodontic rehabilitation. As to the periodontal Surg 2017;46:905-911. benefit, studies have indicated the mesial pocket depth of 5. W ellfelt B, Varpio M. Disturbed eruption of the the mesial tipping mandibular molars could significantly permanent lower second molar: treatment and results. reduce, and the bony morphology of angular defect could ASDC J Dent Child 1988;55:183-189.

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