Produção Nacional
Revisado por pares
Expanding torque possibilities: A skeletally anchored torqued cantilever for uprighting “kissing molars”
2018; Elsevier BV; Volume: 153; Issue: 4 Linguagem: Inglês
10.1016/j.ajodo.2017.12.006
ISSN1097-6752
AutoresSérgio Estelita Barros, Guilherme Janson, Kelly Chiqueto, Eduardo Ferreira, Cassiano Kuchenbecker Rösing,
Tópico(s)Temporomandibular Joint Disorders
Resumo•“Kissing molars” (KMs) are uncommon tooth impactions involving 2 severely tipped mandibular molars.•An innovative skeletally anchored cantilever, which uses the torque principle, is proposed for KM treatment.•KMs were successfully treated, achieving an excellent occlusal balance.•Reasons and guidelines for orthodontic treatment of KMs are discussed. Several uprighting mechanics and devices have been used for repositioning tipped molars. “Kissing molars” (KMs) are an uncommon tooth impaction involving 2 severely tipped mandibular molars with their occlusal surfaces positioned crown to crown, with the roots pointing in opposite directions. Orthodontic uprighting of KMs has not been a usual treatment protocol, and it can be a challenging task due to the severe tipping and double impaction, requiring efficient and well-controlled uprighting mechanics. An innovative skeletally anchored cantilever, which uses the torque principle for uprighting tipped molars, is suggested. This torqued cantilever is easy to manufacture, install, and activate; it is a well-known torque that is effective for producing root movement. A successful treatment of symptomatic KMs, involving the first and second molars, was achieved with this cantilever. Thus, clinicians should consider the suggested uprighting mechanics and orthodontic device as a more conservative alternative to extraction of KMs, depending on the patient's age, involved teeth in KMs, tipping severity, and impaction positions. Several uprighting mechanics and devices have been used for repositioning tipped molars. “Kissing molars” (KMs) are an uncommon tooth impaction involving 2 severely tipped mandibular molars with their occlusal surfaces positioned crown to crown, with the roots pointing in opposite directions. Orthodontic uprighting of KMs has not been a usual treatment protocol, and it can be a challenging task due to the severe tipping and double impaction, requiring efficient and well-controlled uprighting mechanics. An innovative skeletally anchored cantilever, which uses the torque principle for uprighting tipped molars, is suggested. This torqued cantilever is easy to manufacture, install, and activate; it is a well-known torque that is effective for producing root movement. A successful treatment of symptomatic KMs, involving the first and second molars, was achieved with this cantilever. Thus, clinicians should consider the suggested uprighting mechanics and orthodontic device as a more conservative alternative to extraction of KMs, depending on the patient's age, involved teeth in KMs, tipping severity, and impaction positions. Molar uprighting mechanics are frequently required to reposition mesially tipped and impacted molars or when the erupted molars tip toward an edentulous space because of loss or agenesis of an adjacent tooth.1Khouw F.E. Norton L.A. The mechanism of fixed molar uprighting appliances.J Prosthet Dent. 1972; 27: 381-389Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 2Shapira Y. Borell G. Nahlieli O. Kuftinec M.M. Uprighting mesially impacted mandibular permanent second molars.Angle Orthod. 1998; 68: 173-178PubMed Google Scholar However, “kissing molars” (KMs) describe an unusual type of tooth impaction in which 2 mandibular molars are severely tipped and impacted with their occlusal surfaces positioned crown-to-crown and the roots pointing in opposite directions.3Van Hoof R.F. Four kissing molars.Oral Surg Oral Med Oral Pathol. 1973; 35: 284Abstract Full Text PDF PubMed Scopus (17) Google Scholar, 4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar, 6Krishnan B. Kissing molars.Br Dent J. 2008; 204: 281-282Crossref PubMed Scopus (10) Google Scholar, 7Zerener T. Bayar G.R. Altug H.A. Kiran S. Extremely rare form of impaction bilateral kissing molars: report of a case and review of the literature.Case Rep Dent. 2016; 2016: 2560792PubMed Google Scholar, 8McIntyre G. Kissing molars: an unexpected finding.Dent Update. 1997; 24: 373-374PubMed Google Scholar Gulses et al9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar proposed a radiographic classification of KMs into Class I, Class II, or Class III categories depending on the location of the teeth involved. If the impactions are between the first and second molars, they are classified as Class I KMs; between the second and third molars, Class II KMs; and between the third and fourth mandibular molars, Class III KMs.4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar, 10Anish N. Vivek V. Thomas S. Daniel V.A. Thomas J. Ranimol P. Till surgery do us part: unexpected bilateral kissing molars.Clin Pract. 2015; 5: 688Crossref PubMed Google Scholar However, this classification does not set treatment guidelines. KMs should be treated if they cause adverse symptoms, are associated with cystic pathology, or because they have a high risk of caries, periodontal complications, or progressive bone loss.5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar, 9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar Orthodontic mechanics for uprighting KMs have not been reported. Surgical treatment involving extraction of 1 or both KMs is the most common protocol.4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 7Zerener T. Bayar G.R. Altug H.A. Kiran S. Extremely rare form of impaction bilateral kissing molars: report of a case and review of the literature.Case Rep Dent. 2016; 2016: 2560792PubMed Google Scholar, 11Arjona-Amo M. Torres-Carranza E. Batista-Cruzado A. Serrera-Figallo M.A. Crespo-Torres S. Belmonte-Caro R. et al.Kissing molars extraction: case series and review of the literature.J Clin Exp Dent. 2016; 8: e97-101PubMed Google Scholar, 12Boffano P. Gallesio C. Kissing molars.J Craniofac Surg. 2009; 20: 1269-1270Crossref PubMed Scopus (16) Google Scholar, 13Kiran H.Y. Bharani K.S. Kamath R.A. Manimangalath G. Madhushankar G.S. Kissing molars and hyperplastic dental follicles: report of a case and literature review.Chin J Dent Res. 2014; 17: 57-63PubMed Google Scholar The reason for this includes the high severity of the ectopic positions inherent to KMs. When molar tipping is extremely severe, showing a vertically inverted position in a panoramic radiograph (ie, root apex positioned more occlusally than the tooth crown), and the exposure level of the molar crown does not allow placement of uprighting mechanics on its buccal surface, molar uprighting may be a challenging task. This report shows an orthodontic treatment option for Class I KMs, presents an innovative skeletally anchored cantilever to aid in uprighting severely tipped KMs, and discusses reasons and guidelines for orthodontic treatment of this anomaly. A girl, aged 10 years 9 months, sought treatment at the dental school at the Federal University of Rio Grande do Sul in Porto Alegre, Brazil, with a clinical history of recurrent pericoronitis involving the mandibular right molar region. The clinical examination was not enough to provide an accurate diagnosis (Fig 1). Radiographically, the right first and second molars were severely tipped toward each other so that their occlusal surfaces were contacting crown to crown, whereas the roots pointed in opposite directions, in a typical KM impaction position (Fig 2).4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar, 6Krishnan B. Kissing molars.Br Dent J. 2008; 204: 281-282Crossref PubMed Scopus (10) Google Scholar, 7Zerener T. Bayar G.R. Altug H.A. Kiran S. Extremely rare form of impaction bilateral kissing molars: report of a case and review of the literature.Case Rep Dent. 2016; 2016: 2560792PubMed Google Scholar The second molar was the most severely tipped, with a vertically inverted position and over 90° of long axis rotation in relation to the adjacent unaffected teeth (Fig 2). The unerupted surfaces of the KMs presented an enlarged pericoronal space that communicated with the oral cavity, allowing food debris impaction, bacterial contamination, and chronic infection with acute episodes, leading to bone loss (Fig 1, Fig 2). This difficult access for dental cleaning probably led to the development of a deep carious lesion in the first molar (Fig 2).5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar The patient's parents reported a history of a cystic lesion related to the KMs, which had been surgically treated 3 years previously. Since the patient had no history of metabolic diseases, trauma, or fracture involving the KM area, the cystic formation may have contributed to the displacement of the adjacent teeth to the KM position.4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar, 7Zerener T. Bayar G.R. Altug H.A. Kiran S. Extremely rare form of impaction bilateral kissing molars: report of a case and review of the literature.Case Rep Dent. 2016; 2016: 2560792PubMed Google Scholar, 9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar, 11Arjona-Amo M. Torres-Carranza E. Batista-Cruzado A. Serrera-Figallo M.A. Crespo-Torres S. Belmonte-Caro R. et al.Kissing molars extraction: case series and review of the literature.J Clin Exp Dent. 2016; 8: e97-101PubMed Google Scholar, 13Kiran H.Y. Bharani K.S. Kamath R.A. Manimangalath G. Madhushankar G.S. Kissing molars and hyperplastic dental follicles: report of a case and literature review.Chin J Dent Res. 2014; 17: 57-63PubMed Google Scholar, 14Nedjat-Shokouhi B. Webb R.M. Bilateral kissing molars involving a dentigerous cyst: report of a case and discussion of terminology.Oral Sug. 2014; 7: 107-110Crossref Scopus (7) Google Scholar, 15Sá Fortes R.Z. Júnior V.S. Modolo F. Mackowiecky E. Kissing molars: report of a case.J Oral Maxillofac Surg Med Pathol. 2014; 26: 48-51Crossref Scopus (9) Google ScholarFig 2Pretreatment, panoramic, and periapical radiographs. The second molar was the most severely tipped KM with a vertically inverted position (root apex positioned more occlusally than the tooth crown) and over 90° of long-axis rotation in relation to the long axis of adjacent unaffected teeth. Note that the distalization force vector is close to the center of resistance of the severely tipped second molar.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The premolar relationships showed a half cusp Class II malocclusion (Fig 1). Distal tipping of the first molar, associated with mesial tipping of the second molar, caused arch-length shortening in the KM area. The pretreatment dentoskeletal and soft tissue cephalometric features are shown in the Table.TableCephalometric data before and after orthodontic treatmentVariablePretreatmentPosttreatmentDifferenceSNA (°)87.8880.2SNB (°)84.185.31.2ANB (°)3.72.7−1Wits (mm)2.30−2.3SN.GoGn (°)24.9261.1FMA (°)17.618.10.5LAFH (mm)5459.25.2Mx1-NA (°)26.320−6.3Mx1-NA (mm)3.62.7−0.9Md1-NB (°)19.831.211.4Md1-NB (mm)1.64.42.8Overjet (mm)52−3Overbite (mm)3.52.2−1.2Nasolabial angle (°)113.7112.4−1.3Upper lip to E-plane (mm)−0.9−1.2−0.3Lower lip to E-plane (mm)−1.5−0.21.3Inter-KMs angle (°)138.55−133.5 Open table in a new tab The primary treatment objectives were to normalize the posterior occlusion on the KM side and the periodontal health and dental cleaning access, preventing progress of the side effects associated with this developmental anomaly, such as occlusal collapse and bone loss.6Krishnan B. Kissing molars.Br Dent J. 2008; 204: 281-282Crossref PubMed Scopus (10) Google Scholar, 9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar Additional objectives included Class II malocclusion correction and establishment of a functional occlusion. Based on the primary objectives, some treatment alternatives were considered. Extraction of both KMs is the most usual treatment reported.4Menditti D. Laino L. Cicciu M. Mezzogiorno A. Perillo L. Menditti M. et al.Kissing molars: report of three cases and new prospective on aetiopathogenetic theories.Int J Clin Exp Pathol. 2015; 8: 15708-15718PubMed Google Scholar, 5Gonzalez-Perez L.M. Infante-Cossio P. Sanchez-Sanchez M. Valdivieso-del-Pueblo C. Robles-Garcia M. Kissing molars: a report of three cases and literature review.Int J Oral Dent Health. 2015; 1: 1-5Crossref Google Scholar, 6Krishnan B. Kissing molars.Br Dent J. 2008; 204: 281-282Crossref PubMed Scopus (10) Google Scholar, 7Zerener T. Bayar G.R. Altug H.A. Kiran S. Extremely rare form of impaction bilateral kissing molars: report of a case and review of the literature.Case Rep Dent. 2016; 2016: 2560792PubMed Google Scholar, 9Gulses A. Varol A. Sencimen M. Dumlu A. A study of impacted love: kissing molars.Oral Health Dent Manag. 2012; 11: 185-188PubMed Google Scholar, 11Arjona-Amo M. Torres-Carranza E. Batista-Cruzado A. Serrera-Figallo M.A. Crespo-Torres S. Belmonte-Caro R. et al.Kissing molars extraction: case series and review of the literature.J Clin Exp Dent. 2016; 8: e97-101PubMed Google Scholar, 12Boffano P. Gallesio C. Kissing molars.J Craniofac Surg. 2009; 20: 1269-1270Crossref PubMed Scopus (16) Google Scholar, 13Kiran H.Y. Bharani K.S. Kamath R.A. Manimangalath G. Madhushankar G.S. Kissing molars and hyperplastic dental follicles: report of a case and literature review.Chin J Dent Res. 2014; 17: 57-63PubMed Google Scholar, 14Nedjat-Shokouhi B. Webb R.M. Bilateral kissing molars involving a dentigerous cyst: report of a case and discussion of terminology.Oral Sug. 2014; 7: 107-110Crossref Scopus (7) Google Scholar, 15Sá Fortes R.Z. Júnior V.S. Modolo F. Mackowiecky E. Kissing molars: report of a case.J Oral Maxillofac Surg Med Pathol. 2014; 26: 48-51Crossref Scopus (9) Google Scholar, 16Bakaeen G. Baqain Z.H. Interesting case: kissing molars.Br J Oral Maxillofac Surg. 2005; 43: 534Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar However, in this young patient, having Class I KMs, extraction of first and second molars would produce an extensive occlusal sequel and early need for rehabilitation. Extracting only the second molar could be a more conservative and reasonable alternative, taking into account its considerable tip (Fig 2). However, the first molar had a deep carious lesion and some root shortening compared with the contralateral tooth (Fig 2). Furthermore, the potential replacement of the second molar with the third molar, which was in the early stage of cusp calcification, raised treatment success uncertainties regarding the third molar's anatomic characteristics, including its shape, structure, and dimensions.17Altalie S. Thevissen P. Willems G. Classifying stages of third molar development: crown length as a predictor for the mature root length.Int J Legal Med. 2015; 129: 165-169Crossref PubMed Scopus (6) Google Scholar Treatment time would also be greatly increased waiting for the eruption of the third molar, to adequately position this molar and close residual spaces. Finally, replacement of the second molar with a dental implant instead of the third molar could also be disadvantageous because the patient has a long growth period ahead, which contraindicates implant placement in the short term while risking bone loss in the extraction area. An alternative and conservative approach would be to extract the damaged first molar, but this option must take into account that treatment success would depend on the less predictable results of uprighting an extremely tipped second molar. The previously mentioned drawbacks, such as developmental uncertainties regarding the third molar, increased treatment time, and need for closing the residual spaces also applied to this protocol, as well as to bone loss in case of an implant rehabilitation choice. Lastly, it must be considered that, unlike second molar extraction, first molar removal would require the difficult task of mesializing 2 molars. The factors that influenced the decision to treat this Class I KM patient using a nonextraction protocol were the following: the patient's young age, the need for immediate clinical intervention, the early development stage of the third molar, the moderate preservation of the dental structure of the KMs, and the parental reluctance to accept an extraction treatment plan. Thus, any of the previously discussed extraction protocols involving late third molar handling would still be available if for some reason the repositioning of the KMs proved to be unsuccessful. The orthodontic treatment began with a focused intervention on KMs because of the urgent patient need and because not all permanent teeth were erupted at this time. Due to the arch-space deficiency for first molar repositioning, KM correction was started with uprighting of the second molar. However, the position and exposure degree of the second molar crown was not favorable for conventional buccal uprighting mechanics (Fig 1).1Khouw F.E. Norton L.A. The mechanism of fixed molar uprighting appliances.J Prosthet Dent. 1972; 27: 381-389Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 2Shapira Y. Borell G. Nahlieli O. Kuftinec M.M. Uprighting mesially impacted mandibular permanent second molars.Angle Orthod. 1998; 68: 173-178PubMed Google Scholar, 18Sawicka M. Racka-Pilszak B. Rosnowska-Mazurkiewicz A. Uprighting partially impacted permanent second molars.Angle Orthod. 2007; 77: 148-154Crossref PubMed Scopus (50) Google Scholar In addition, uprighting mechanics that are based on distalization force vectors cannot produce an effective uprighting moment when the molar is extremely tipped because the line of force action lies close to the center of resistance of the tipped molar (Fig 2).19Mah S.J. Won P.J. Nam J.H. Kim E.C. Kang Y.G. Uprighting mesially impacted mandibular molars with 2 miniscrews.Am J Orthod Dentofacial Orthop. 2015; 148: 849-861Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar, 20Majourau A. Norton L.A. Uprighting impacted second molars with segmented springs.Am J Orthod Dentofacial Orthop. 1995; 107: 235-238Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar, 21Nienkemper M. Ludwig B. Kanavakis G. Pauls A. Wilmes B. Drescher D. Uprighting mesially impacted lower third molars with skeletal anchorage.J Clin Orthod. 2016; 50: 420-426PubMed Google Scholar Consequently, some distal movement of the second molar roots could occur; this would be undesirable (Fig 2). Thus, an innovative skeletally anchored cantilever made of stainless steel rectangular wire (0.019 × 0.025 in) was proposed. This cantilever was created to satisfy the clinical conditions and the mechanical objectives of this patient (Fig 3). A mini-implant was inserted between the canine and the first premolar to prevent the undesirable side effects from cantilever intrusion force. Unlike the usual cantilever mechanics, this new uprighting device uses the torque principle to move the roots in a mesiodistal direction (Fig 4). Torque is a twisting force traditionally used to produce tooth movement in a buccolingual direction. To achieve this new torque effect, an orthodontic tube was bonded with its slot buccolingually positioned on the erupted part of the occlusal surface of the impacted tooth (Figs 3, A and B, and 4, B). Thus, when this torqued cantilever is actively inserted into the molar tube, a mesiodistal moment of force is applied on the molar roots, producing an uprighting effect (Figs 3, C and D, and 4).Fig 4Torqued cantilever mechanics: A, this cantilever is activated by torquing the end of the rectangular wire that is inserted into the molar tube; B, since the molar tube is bonded buccolingually on the occlusal surface of the KM, the torque action of this cantilever will produce an uprighting movement of the impacted molar.View Large Image Figure ViewerDownload Hi-res image Download (PPT) After 5 months of uprighting mechanics with this skeletally anchored torqued cantilever, the second molar position was significantly corrected, and its buccal surface was clinically accessible, allowing orthodontic tube repositioning (Fig 5, A and B). A temporary bite raising was performed by adding light-curing composite resin on the occlusal surface of the maxillary premolars, allowing initial mandibular arch leveling. An open-coil spring was used to open space for the first molar repositioning and to aid in the second molar uprighting since the distalization force vector was away from the molar resistance center in this advanced uprighting stage, producing an efficient moment of force for uprighting (Figs 5, B and C, and 6). After space opening, a closed-coil spring was used to maintain the space, and first molar alignment was started with an auxiliary nickel-titanium wire inserted into the orthodontic tube bonded on its occlusal surface because the buccal surface was not accessible (Fig 5, D). At this stage, the KMs underwent periodontal surgery by means of an apically repositioned full-thickness flap to expose a greater amount of their clinical crowns, allowing repositioning of orthodontic accessories on the buccal surfaces (Fig 5, E). After 1 year, the second molar was uprighted, and the first molar correction was in progress (Fig 5, F). Positioning of the KMs progressively improved until total correction (Figs 5, G and H).Fig 6Moment of force produced by distalization forces depending on the degree of molar tipping: A, extreme molar tipping can reduce the distance (d) between the center of resistance (CR) of the molar and the distalization force vector (F), compromising the moment of force (M=Fxd) for molar uprighting; B, when the molar tipping degree is not extreme, distalization forces (F) can be indicated to produce an efficient moment of force (M) for molar uprighting and recovery of the arch space reduced by molar tipping.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Accentuated and reverse curves of Spee were used to correct the overbite. A Class I molar relationship was obtained with Class II elastics. However, the treatment finishing phase had to be postponed because the restorative treatment of the first molar's carious lesion was not successful and required endodontic treatment. Orthodontic treatment was discontinued for 2 months while the patient was endodontically treated, after which the finishing phase began. Although the root canal filling lengths and homogeneities were not ideal, there was no periapical pathology or patient symptom afterward. Orthodontic treatment was completed in 3.2 years (Fig 7, Fig 8).Fig 8Posttreatment facial and intraoral photographs.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Adequate positioning of the KMs was achieved (Fig 8, Fig 9). The first and second molars were uprighted by 133° until satisfactory root parallelism (5°) was reached between them (Table; Fig 9, Fig 10). The external apical root resorption of the KMs was not excessive, maintaining the initial root shortening of the first molar (Fig 2, Fig 9). The lost alveolar bone height between the KMs progressively recuperated as they were uprighted (Fig 2, Fig 5). The mesial surface of the second molar and the distal surface of the first molar were significantly extruded during the uprighting process, allowing recovery of the bone crest level (Fig 9). Clinically, the patient was completely asymptomatic, the pseudopocket was eliminated, the KMs were periodontally healthy, and pericoronitis recurrence was eliminated (Fig 8, Fig 9).Fig 10Overall superimposed tracings. Black, pretreatment; red, posttreatment.View Large Image Figure ViewerDownload Hi-res image Download (PPT) In addition, molar relationship, overjet, and overbite were normalized; this contributed to a well-finished static and functional occlusion (Fig 7, Fig 8). The dentoskeletal and soft tissue changes are shown in the Table and Figure 10. The final smile esthetics were pleasant because midlines, smile arc, and buccal corridors were adequate (Fig 8).22Janson G. Branco N.C. Fernandes T.M. Sathler R. Garib D. Lauris J.R. Influence of orthodontic treatment, midline position, buccal corridor and smile arc on smile attractiveness.Angle Orthod. 2011; 81: 153-161Crossref PubMed Scopus (66) Google Scholar, 23Parekh S.M. Fields H.W. Beck M. Rosenstiel S. Attractiveness of variations in the smile arc and buccal corridor space as judged by orthodontists and laymen.Angle Orthod. 2006; 76: 557-563PubMed Google Scholar Correction of the KMs was stable 10 months after orthodontic treatment (Fig 11). Extraction of the most distal Class II KM and both Class III KMs may be a less controversial decision because in both cases the extractions do not involve the first and second molars, and bone availability in the retromolar area is often critical to accommodate the third molars and certainly insufficient for a fourth molar if all other teeth are present. However, nonextraction treatment should be considered for patients in the late mixed dentition and with symptomatic Class I KMs because first or second molar extraction may be disadvantageous. Nevertheless, it would require using unique orthodontic mechanics because of the severe ectopic positioning inherent to KMs. Based on a recent literature search and as far as we know, there has been no reported case of orthodontically treated KMs.13Kiran H.Y. Bharani K.S. Kamath R.A. Manimangalath G. Madhushankar G.S. Kissing molars and hyperplastic dental follicles: report of a case and literature review.Chin J Dent Res. 2014; 17: 57-63PubMed Google Scholar Several orthodontic mechanics and devices have been proposed to verticalize and disimpact the mesially tipped mandibular molars. Removable and fixed appliances and, more recently, skeletal anchorage have been used with push springs,24Reddy S.K. Uloopi K.S. Vinay C. Subba Reddy V.V. Orthodontic uprighting of impacted mandibular permanent second molar: a case report.J Indian Soc Pedod Prev Dent. 2008; 26: 29-31Crossref PubMed Scopus (4) Google Scholar, 25Henns R.J. Uprighting impacted mandibular second molars.Angle Orthod. 1975; 45: 314-315PubMed Google Scholar open-coil and closed-coil springs,1Khouw F.E. Norton L.A. The mechanism of fixed molar uprighting appliances.J Prosthet Dent. 1972; 27: 381-389Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 21Nienkemper M. Ludwig B. Kanavakis G. Pauls A. Wilmes B. Drescher D. Uprighting mesially impacted lower third molars with skeletal anchorage.J Clin Orthod. 2016; 50: 420-426PubMed Google Scholar, 26Giancotti A. Germano F. Greco M. An uprighting auxiliary for deeply impacted mandibular molars.J Clin Orthod. 2013; 47: 255-259PubMed Google Scholar, 27Giancotti A. Arcuri C. Barlattani A. Treatment of ectopic mandibular second molar with titanium miniscrews.Am J Orthod Dentofacial Orthop. 2004; 126: 113-117Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar tip-back cantilevers,1Khouw F.E. Norton L.A. The mechanism of fixed molar uprighting appliances.J Prosthet Dent. 1972; 27: 381-389Abstract Full Text PDF PubMed Scopus (12) Google Scholar, 2Shapira Y. Borell G. Nahlieli O. Kuftinec M.M. Uprighting mesially impacted mandibular permanent second molars.Angle Orthod. 1998; 68: 173-178PubMed Google Scholar, 18Sawicka M. Racka-Pilszak B. Rosnowska-Mazurkiewicz A. Uprighting partially impacted permanent second molars.Angle Orthod. 2007; 77: 148-154Crossref PubMed Scopus (50) Google Scholar, 28Simon R.L. Rationale and practical technique for uprighting mesially inclined molars.J Prosthet Dent. 1984; 52: 256-259Abstract Full Text PDF PubMed Scopus (10) Google Scholar looped springs,19Mah S.J. Won P.J. Nam J.H. Kim E.C. Kang Y.G. Uprighting mesially impacted mandibular molars with 2 miniscrews.Am J Orthod Dentofacial Orthop. 2015; 148: 849-861Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar and several other types and designs of uprighting springs29Nienkemper M. Pauls A. Ludwig B. Wilmes B. Drescher D. Preprosthetic molar uprighting using skeletal anchorage.J Clin Orthod. 2013; 47: 433-437PubMed Google Scholar, 30Kogod M. Kogod H.S. Molar uprighting with the piggyback buccal sectional arch wire technique.Am J Orthod Dentofacial Orthop. 1991; 99: 276-280Abstract Full Text PDF PubMed Scopus (10) Google Scholar, 31Kalantar Motamedi M.R. Heidarpour M. Siadat S. Kalantar Motamedi A. Bahreman A.A. Orthodontic extraction of high-risk impacted mandibular third molars in close proximity to the mandibular canal: a systematic review.J Oral Maxillofac Surg. 2015; 73: 1672-1685Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar, 32Fu P.S. Wang J.C. Chen C.H. Huang T.K. Tseng C.H. Hung C.C. Management of unilaterally deep impacted first, second, and third mandibular molars.Angle Orthod. 2012; 82: 565-571Crossref PubMed Scopus (6) Google Scholar to perform the challenging task of uprighting tipped molars. However, this is the first time that a moment of force used for molar uprighting has been obtained by an actively torqued rectangular archwire. This new use of archwire torque seemed to be as effective in accomplishing mesiodistal root movement as its traditional use to move the roots buccolingually. In this patient, second molar uprighting occurred mainly at the expense of torque movement, which is associated with extensive root repositioning and minor crown displacement in the opposite direction.33Strang R.H. A discussion of torque force as available in the edgewise arch mechanism.Angle Orthod. 1932; 2: 88-111Google Scholar This mechanical characteristic can be a clinical advantage when root movement is prioritized during the uprighting process. A clinical advantage of the skeletally anchored torqued cantilever is that it does not depend on exposure of the buccal surface of the tooth, as generally required by conventional cantilevers, because this area is frequently unavailable in patients with extremely tipped and partially erupted mandibular molars.2Shapira Y. Borell G. Nahlieli O. Kuftinec M.M. Uprighting mesially impacted mandibular permanent second molars.Angle Orthod. 1998; 68: 173-178PubMed Google Scholar, 18Sawicka M. Racka-Pilszak B. Rosnowska-Mazurkiewicz A. Uprighting partially impacted permanent second molars.Angle Orthod. 2007; 77: 148-154Crossref PubMed Scopus (50) Google Scholar, 29Nienkemper M. Pauls A. Ludwig B. Wilmes B. Drescher D. Preprosthetic molar uprighting using skeletal anchorage.J Clin Orthod. 2013; 47: 433-437PubMed Google Scholar Another mechanical advantage is that the moment of force produced by the skeletally anchored torqued cantilever, unlike some uprighting mechanics, does not depend on any distal force. Extremely tipped mandibular molars frequently have the center of resistance close to the line of action of the distal forces, generating reduced moments of force and tending to produce distal bodily movement of the tipped molar, which can reduce molar uprighting efficiency (Fig 2, Fig 6). Mini-implant insertion between the first premolar and the canine allowed use of a longer cantilever arm, which contributed to preventing excessive molar extrusion during uprighting (Fig 3, Fig 4).18Sawicka M. Racka-Pilszak B. Rosnowska-Mazurkiewicz A. Uprighting partially impacted permanent second molars.Angle Orthod. 2007; 77: 148-154Crossref PubMed Scopus (50) Google Scholar Furthermore, a longer cantilever arm can deliver a relatively low load-deflection rate, providing the force system with a high degree of constancy, which can benefit the extensive root movement required for uprighting.18Sawicka M. Racka-Pilszak B. Rosnowska-Mazurkiewicz A. Uprighting partially impacted permanent second molars.Angle Orthod. 2007; 77: 148-154Crossref PubMed Scopus (50) Google Scholar Lastly, activation of a conventional cantilever produces a well-known vertical deflection of this device, while with the skeletally anchored torqued cantilever a torsional deflection of the rectangular wire occurs simultaneously with the vertical deflection (Fig 3, Fig 4). This dual deflection system of the skeletally anchored torqued cantilever with a longer cantilever arm further reduces the load-deflection rate and ensures uniformity of the cantilever force, making the use of helical loops and flexible metal alloys, such as titanium-molybdenum alloy, unnecessary. In this patient with KMs, the first molar buccal enamel defect could not be clinically or radiographically diagnosed at the beginning of treatment, and endodontic treatment need was not a certainty at that time (Fig 1, Fig 2). However, the survival of endodontically treated teeth has been shown to be about 93% after 10 years, suggesting a good prognosis.34Fonzar F. Fonzar A. Buttolo P. Worthington H.V. Esposito M. The prognosis of root canal therapy: a 10-year retrospective cohort study on 411 patients with 1175 endodontically treated teeth.Eur J Oral Implantol. 2009; 2: 201-208PubMed Google Scholar Despite the low root-crown ratio of the mandibular right first molar (1.1), it was not so below the molar norm, and the 1:1 prosthetic parameter for minimal root-crown ratio was satisfactorily maintained.35Yun H.J. Jeong J.S. Pang N.S. Kwon I.K. Jung B.Y. Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population.J Adv Prosthodont. 2014; 6: 171-176Crossref PubMed Scopus (17) Google Scholar The radiolucency involving the mesial root of the second molar at the end of treatment was not indicative for endodontic treatment because the pulp vitality test did not suggest necrosis; the patient was asymptomatic; the carious lesions were inactive and restricted to fissures, and bone reorganization around the roots was in progress after extensive KM movement. Radiographic follow-up showed that this was the right clinical decision (Fig 11). The second and third molars' overlapping on the right side did not seem to be due to uncontrolled KMs uprighting mechanics because an even greater overlapping was seen on the opposite side, where no distal movement was performed. Arch-length discrepancy in this area seems to be the most determinant factor for that. Despite the potential impaction, if the third molar is asymptomatic and has no associated pathology or detrimental condition, prophylactic extraction has not been supported in the scientific literature, and professional monitoring seems to be a reasonable decision.36Brickley M. Kay E. Shepherd J.P. Armstrong R.A. Decision analysis for lower-third-molar surgery.Med Decis Making. 1995; 15: 143-151Crossref PubMed Scopus (56) Google Scholar, 37Mettes T.G. Nienhuijs M.E. van der Sanden W.J. Verdonschot E.H. Plasschaert A.J. Interventions for treating asymptomatic impacted wisdom teeth in adolescents and adults.Cochrane Database Syst Rev. 2005; : CD003879PubMed Google Scholar In this patient, third molar follow-up can be further advantageous because it remains as an orthodontic option to replace the second molar if first molar extraction is eventually required in the long term. If the first molar has unfavorable changes over time, it should be considered for extraction because of its less preserved dental structure. First molar extraction would allow suitable third molar positioning, but the cost-benefit rate of this hypothetic treatment should be carefully considered with the patient. She has a well-established Class I molar relationship, and mesialization of 2 molars through a molar width is always a hard and time-consuming task, even when skeletal anchorage is used. If this option is not accepted by the patient, first molar extraction and implant-restorative treatment should be proposed. In this situation, no previous orthodontic treatment would be needed because the second molar has already been uprighted, and implant bone availability would be guaranteed by the opportune presence of the first molar. Finally, the radiographic follow-up of the third molar did not show molar overlapping, reinforcing third molar follow-up indication (Fig 11). This molar overlapping improvement may have been due to the continuous mandibular growth and posterior relocation of the ramus, in addition to the progress of third molar development into a favorable eruption axis.38Erdem D. Ozdiler E. Memikoglu U.T. Baspinar E. Third molar impaction in extraction cases treated with the Begg technique.Eur J Orthod. 1998; 20: 263-270Crossref PubMed Scopus (8) Google Scholar Despite the complexity and adversities, this treatment could be considered successful because it reached its main objectives, and the results were stable, suggesting that when the KMs have an angular positioning about 140° between each other, with an impaction depth at the level of the alveolar ridge, orthodontic treatment using similar uprighting mechanics could be a reasonable option to solve this problem. This is especially true if the KMs are symptomatic, the first and second molars are implicated (Class I KMs), the patient is young (mixed or early permanent dentition), normal third molar development cannot be predicted or the third molar is missing, risks of caries and periodontal damage are present, and the patient or his or her parents do not agree to have extractions performed. Early treatment of Class I KMs can prevent progression of periodontal disease, bone loss, and carious lesions, allowing preservation of the mandibular first and second molars. However, the severity and complexity of the positions of the KMs require efficient and proper molar uprighting mechanics for successful nonextraction treatment. This can be achieved with the aid of a skeletally anchored torqued cantilever, which can perform an extensive root uprighting movement with minimal side effects, allowing easier clinical handling of extremely tipped and partially erupted KMs.
Referência(s)