Orthodontic management of a patient with short root anomaly and impacted teeth
2019; Elsevier BV; Volume: 155; Issue: 3 Linguagem: Inglês
10.1016/j.ajodo.2018.11.009
ISSN1097-6752
AutoresMeenakshi Vishwanath, Po‐Jung Chen, Madhur Upadhyay, Sumit Yadav,
Tópico(s)Dental Trauma and Treatments
ResumoShort root anomaly (SRA) is a rare familial dental condition that is often misdiagnosed. Orthodontic treatment of patients with SRA is challenging because it is difficult to diagnose, it may be accompanied by other dental anomalies, and it has been reported to contribute to additional susceptibility to root resorption during orthodontic treatment. In this article, we describe a methodical and evidence-based means of diagnosing and orthodontically managing a patient with SRA. The patient had additional challenges, including impacted and ectopic teeth. An individualized treatment plan that incorporated efficient and effective mechanics led to a well seated occlusion and an esthetic smile. Short root anomaly (SRA) is a rare familial dental condition that is often misdiagnosed. Orthodontic treatment of patients with SRA is challenging because it is difficult to diagnose, it may be accompanied by other dental anomalies, and it has been reported to contribute to additional susceptibility to root resorption during orthodontic treatment. In this article, we describe a methodical and evidence-based means of diagnosing and orthodontically managing a patient with SRA. The patient had additional challenges, including impacted and ectopic teeth. An individualized treatment plan that incorporated efficient and effective mechanics led to a well seated occlusion and an esthetic smile. Short root anomaly (SRA) is a rare condition in which the roots of the teeth are abnormally short and blunted albeit complete in formation. SRA has been reported intermittently in the literature, with a definitive description of the anomaly in 1972.1Lind V. Short root anomaly.Scand J Dent Res. 1972; 80: 85-93PubMed Google Scholar The pathognomonic features of SRA are as follows: The teeth have short plump roots with rounded apices and crown-to-root ratios of 1:1; the shortness of the root (rizomicry) is not due to root resorption or any factor that is exogenous in origin; there is familial predilection; the apices of the roots are closed; and the teeth are often asymptomatic.1Lind V. Short root anomaly.Scand J Dent Res. 1972; 80: 85-93PubMed Google Scholar The prevalence of SRA among white populations has been reported as 1.3%2Apajalahti S. Holtta P. Turtola L. Pirinen S. Prevalence of short-root anomaly in healthy young adults.Acta Odontol Scand. 2002; 60: 56-59Crossref PubMed Scopus (43) Google Scholar-2.4%.3Jakobsson R. Lind V. Variation in root length of the permanent maxillary central incisor.Scand J Dent Res. 1973; 81: 335-338Google Scholar Generalized forms of rizomicry have been reported,4Puranik C.P. Hill A. Henderson Jeffries K. et al.Characterization of short root anomaly in a Mexican cohort—hereditary idiopathic root malformation.Orthod Craniofac Res. 2015; 18: 62-70Crossref PubMed Scopus (13) Google Scholar and a higher prevalence for localization of the condition in the maxillary incisors and premolars has been observed.5Apajalahti S. Sorsa T. Ingman T. Matrix metalloproteinase-2, -8, -9, and -13 in gingival crevicular fluid of short root anomaly patients.Eur J Orthod. 2003; 25: 365-369Crossref PubMed Scopus (19) Google Scholar Baccetti et al found a correlation between distal inclination of the mandibular second premolar bud and palatally displaced canines, small maxillary lateral incisors, and dental aplasia.6Baccetti T. Leonardi M. Giuntini V. Distally displaced premolars: a dental anomaly associated with palatally displaced canines.Am J Orthod Dentofacial Orthop. 2010; 138: 318-322Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar These anomalies in turn have been associated with SRA,7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar suggesting the presence of an altered gene-regulatory mechanism. Therefore, the percentages cited above may be underrepresentative, especially because SRA may be part of a continuous spectrum of dental anomalies. Differential diagnosis for teeth with short roots can be challenging, especially in a young patient. For more generalized forms of SRA, the existence of definitive etiologic factors, such as systemic factors,8Wang Z.Y. Zhang K. Zheng G.S. Qiao W. Su Y.X. Current concepts in odontohypophosphatasia form of hypophosphatasia and report of two cases.BMC Oral Health. 2016; 16: 70Crossref PubMed Scopus (10) Google Scholar syndromes9Brook U. Stevens-Johnson syndrome and abnormal root development: a case report.Int J Paediatr Dent. 1994; 4: 101-103Crossref PubMed Scopus (9) Google Scholar, 10Roinioti T.D. Stefanopoulos P.K. Short root anomaly associated with Rothmund-Thomson syndrome.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007; 103: e19-e22Abstract Full Text Full Text PDF Scopus (22) Google Scholar, 11Robotta P. Schafer E. Hallermann-Streiff syndrome: case report and literature review.Quintessence Int. 2011; 42: 331-338Google Scholar and genetic disorders,12Fulari S.G. Tambake D.P. Rootless teeth: dentin dysplasia type I.Contemp Clin Dent. 2013; 4: 520-522Google Scholar must be investigated. However, generalized forms of SRA with an associated familial history can occur in isolation of other conditions.4Puranik C.P. Hill A. Henderson Jeffries K. et al.Characterization of short root anomaly in a Mexican cohort—hereditary idiopathic root malformation.Orthod Craniofac Res. 2015; 18: 62-70Crossref PubMed Scopus (13) Google Scholar, 13Edwards D.M. Roberts G.J. Short root anomaly.Br Dent J. 1990; 169: 292-293Google Scholar Differential diagnosis for localized forms of SRA can include incomplete or delayed root formation and/or root hypoplasia occurring after dental trauma, and they must be ruled out with the use of a thorough dental and family history.14Valladares Neto J. Rino Neto J. de Paiva J.B. Orthodontic movement of teeth with short root anomaly: should it be avoided, faced or ignored?.Dental Press J Orthod. 2013; 18: 72-85Crossref PubMed Scopus (14) Google Scholar However, the most common misdiagnosis for both localized and generalized SRA is idiopathic root resorption (IRR),7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar because both are asymptomatic with a predilection for females.2Apajalahti S. Holtta P. Turtola L. Pirinen S. Prevalence of short-root anomaly in healthy young adults.Acta Odontol Scand. 2002; 60: 56-59Crossref PubMed Scopus (43) Google Scholar, 15Iwamatsu-Kobayashi Y. Satoh-Kuriwada S. Yamamoto T. et al.A case of multiple idiopathic external root resorption: a 6-year follow-up study.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005; 100: 772-779Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar Some helpful diagnostic clues to differentiate SRA and IRR are: (1) SRA is usually bilaterally symmetric1Lind V. Short root anomaly.Scand J Dent Res. 1972; 80: 85-93PubMed Google Scholar, 2Apajalahti S. Holtta P. Turtola L. Pirinen S. Prevalence of short-root anomaly in healthy young adults.Acta Odontol Scand. 2002; 60: 56-59Crossref PubMed Scopus (43) Google Scholar with smooth apical blunting as opposed to irregularities in the root accompanying resorption16Sogur E. Sogur H.D. Baksi Akdeniz B.G. Sen B.H. Idiopathic root resorption of the entire permanent dentition: systematic review and report of a case.Dent Traumatol. 2008; 24: 490-495Crossref PubMed Scopus (18) Google Scholar; and (2) association with other developmental anomalies and familial history also provide helpful diagnostic clues for SRA.7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar The distinction between the two is important from a clinical standpoint because IRR, unlike SRA, may have varying periods of progressive resorption.15Iwamatsu-Kobayashi Y. Satoh-Kuriwada S. Yamamoto T. et al.A case of multiple idiopathic external root resorption: a 6-year follow-up study.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005; 100: 772-779Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar, 16Sogur E. Sogur H.D. Baksi Akdeniz B.G. Sen B.H. Idiopathic root resorption of the entire permanent dentition: systematic review and report of a case.Dent Traumatol. 2008; 24: 490-495Crossref PubMed Scopus (18) Google Scholar Although certain reports have noted an increased propensity for root resorption in patients with SRA,1Lind V. Short root anomaly.Scand J Dent Res. 1972; 80: 85-93PubMed Google Scholar, 7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar it has not been corroborated through research. It can be hypothesized that the increased susceptibility is probably due to known risk factors for root resorption in patients undergoing orthodontic treatment,17Samandara A. Papageorgiou S.N. Ioannidou-Marathiotou I. Kavvadia-Tsatala S. Papadopoulos M.A. Evaluation of orthodontically induced external root resorption following orthodontic treatment using cone beam computed tomography (CBCT): a systematic review and meta-analysis.Eur J Orthod. 2018; ([Epub ahead of print])Google Scholar such as a decrease in the ratio of root to crown,18Oyama K. Motoyoshi M. Hirabayashi M. Hosoi K. Shimizu N. Effects of root morphology on stress distribution at the root apex.Eur J Orthod. 2007; 29: 113-117Crossref PubMed Scopus (47) Google Scholar as well as an anomalous dental morphology19Thongudomporn U. Freer T.J. Anomalous dental morphology and root resorption during orthodontic treatment: a pilot study.Aust Orthod J. 1998; 15: 162-167PubMed Google Scholar and not due to the inherent nature of the anomaly. This report presents the orthodontic management and treatment of a patient with SRA associated with multiple impacted teeth, ectopically erupted teeth, and peg-shaped laterals. It also discusses the diagnostic and clinical considerations for orthodontic treatment of SRA patients. A 14-year-old postpubertal girl presented to our orthodontic clinic with the chief complaint of gaps between her upper front teeth. The patient's medical history was noncontributory and she had received regular dental care. She had a symmetric mesoprosopic face with a convex soft tissue profile, obtuse nasolabial angle, and retrusive lips. Intraorally, she had a Class I molar relationship bilaterally, with her left molars in crossbite. The upper right canine was ectopically erupted and she had microdontia of her upper lateral incisors. The dentition was spaced in both arches (Fig 1). Panoramic radiographs revealed distally tipped and unerupted mandibular second premolars with delayed apical closure, impacted upper left canine, and shortened roots on all upper premolars, lower second premolars, and the distal roots of the upper first molars (Fig 2). Cephalometric analysis indicated a skeletal Class I relationship with a normovergent mandibular plane angle. The upper and lower incisors were slightly retroclined. The upper and lower lips were retrusive to the E-line (Fig 3; Table I).Fig 2Pretreatment panoramic radiograph.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 3Pretreatment lateral cephalometric radiograph.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Table ICephalometric analysisMeasurementNormalBefore treatmentAfter treatmentSNA (°)82.0 ± 2.07979SNB (°)80.0 ± 2.076.576.5ANB (°)2.0 ± 2.02.52.5SN-MP (°)32.0 ± 5.03636FMA (°)24.0 ± 4.52526U1-SN (°)102.0 ± 5.59790U1-NA (mm)4.3 ± 2.731L1-MP (°)95.0 ± 79594L1-NB (mm)4.0 ± 1.843.5Interincisal angle (°)130.0 ± 6.0135138Upper lip to E-line (mm)−4.0 ± 2.0−8−10Lower lip to E-line (mm)−2.0 ± 2.0−7−7 Open table in a new tab An accurate diagnosis was imperative to provide optimal treatment and address the patient's chief complaint. To buccolingually locate the impacted teeth and simultaneously analyze the crown-to-root ratios, intraoral periapical (IOPA) radiographs were taken and the Clark rule or the buccal object rule was applied (Fig 4). Before exposure of the impacted teeth, the periodontist requested a cone-beam computed tomographic (CBCT) scan, which is considered the standard of care in unusual impactions such as the lower left second premolar. Because both impacted teeth were on the left side, a CBCT scan with a limited field of view captured both teeth (Fig 5). We also examined previously available panoramic radiographs of the patient's parents and sibling (Fig 6). Shortened premolar roots and an impacted tooth were diagnosed in her sibling's radiograph. The diagnosis of SRA was made for the patient based on the presence of familial inheritance, bilateral symmetry, root morphology, and associated developmental anomalies.Fig 5CBCT images of impacted upper left canine and lower left second premolar.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 6Panoramic radiographs of patient's family: A, father; B, mother; C, older sister.View Large Image Figure ViewerDownload Hi-res image Download (PPT) In accordance with the pretreatment records and the patient's chief complaint, the treatment objectives were to (1) prevent any further root shortening in teeth with SRA (due to unusual root morphology), (2) carefully expose and orthodontically extrude the impacted teeth and bring the ectopically erupted teeth into alignment, thereby closing the spaces in both the maxillary and mandibular arches, (3) correct the crossbite in the left molar region, (4) maintain Class I molar relationship bilaterally, and (5) achieve ideal overjet and overbite as well as coincident dental and facial midlines with good smile esthetics. Keeping in view our treatment objectives and to attain the best esthetic and functional results, 2 treatment options were proposed to the patient. Both were nonextraction options, taking into consideration the patient's profile, lip support, and space analysis. The first option was to use the concept of therapeutic diagnosis and proceed with regular mechanics without anchorage reinforcement for the orthodontic traction of the impacted teeth. To determine the susceptibility of teeth with SRA to resorption, it was proposed to initially bond only 1 of the upper premolars bilaterally (first premolar) and apply orthodontic force. Furthermore, follow-up periapical radiographs of the upper premolars were built into the plan. Based on the response of the teeth with SRA that were bonded, the exposure and orthodontic traction of the impacted teeth and bonding of the control teeth with SRA would be planned. The second option involved the use of temporary anchorage device–supported traction of the impacted teeth with delayed bonding of other teeth along with minimal orthodontics for aligning and finishing. This option was considered because earlier reports have found that underestimation of anchorage demands is one of the major reasons for failure in the treatment of impacted canines.20Becker A. Chaushu G. Chaushu S. Analysis of failure in the treatment of impacted maxillary canines.Am J Orthod Dentofacial Orthop. 2010; 137: 743-754Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar Therefore, this option was also presented as an alternate plan to the first option if the teeth with SRA did not respond well to orthodontic forces. Risks and benefits for each treatment option were discussed at length with the patient and her parents, and the first treatment option was adopted with their consent. Preadjusted edgewise brackets (0.022 × 0.028 inch) were bonded on all erupted teeth except the upper second premolars, which served as control teeth. The upper right canine was bypassed during initial leveling. Both arches were leveled and aligned with the use of 0.016-inch nickel-titanium (NiTi) continuous archwires. Periodic radiographic evaluations of the upper premolar region were obtained every 3 months (Fig 7). Visual inspection indicated no drastic change in the root length and morphology of the maxillary first premolars. Six months into the treatment, the upper second premolars were bonded and both arches were built up to 0.019 × 0.025-inch stainless steel archwires sequentially. Orthodontic traction was applied by means of piggyback mechanics with the use of NiTi wires to the upper right canine and lower right second premolar, which was surgically exposed in the orthodontic clinic itself owing to its superficial positioning (Fig 8). At this time, a decision was made to expose and orthodontically extrude the impacted teeth, namely, the upper left canine and lower left second premolar. Based on progression of the root development of the lower left second premolar toward apical closure and the diagnosis of SRA for the contralateral second premolar, it seemed unlikely that the lower left second premolar would develop a longer root. Moreover, studies have demonstrated that orthodontic movement of immature teeth does not lead to adverse effects in root formation and in fact may be advantageous.21Mavragani M. Boe O.E. Wisth P.J. Selvig K.A. Changes in root length during orthodontic treatment: advantages for immature teeth.Eur J Orthod. 2002; 24: 91-97Crossref PubMed Scopus (53) Google Scholar The patient was referred to the department of periodontics for the exposure of the upper left canine and lower left second premolar (Fig 9, A). The CBCT image revealed a fairly uncomplicated midalveolar positioning of the upper left canine with mild resorption of the cervical third of the adjacent upper left lateral incisor. In contrast, the lower left second premolar was distolingually tipped and approximating the mesial root of the first molar and placed 4-5 mm deep within the alveolar bone (Fig 5). After exposure, the initial force on the lower left second premolar was applied with the use of an elastic chain to mesialize the tooth away from the molar root (Fig 9, B). Once it had moved away from the molar root, a cantilever was used to bring the premolar into the arch (Fig 9, C and D). A follow-up radiograph was taken to assess the root development and tooth position (Fig 9, F).Fig 8Progress intraoral photograph: extrusion of upper right canine and lower right second premolar.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 9Progress intraoral photographs: orthodontic traction of the lower left second premolar and follow-up radiograph.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Eighteen months into treatment, all teeth were leveled and aligned and space closure was completed. A panoramic radiograph was taken to assess the positions of the roots as well as evaluate for root resorption. Bracket repositioning followed by finishing and detailing was completed. To obtain ideal overjet despite the tooth-size discrepancy, the patient was given options of building up the upper laterals versus interproximal reduction in the lower anterior region. The patient chose the latter option. The total treatment time was 24 months. A Hawley retainer was delivered in the upper arch, and a lingual fixed retainer was bonded on the lower anterior teeth for retention. The patient was very satisfied with the result because her chief complaint had been addressed and she had an esthetically pleasing smile, as seen in the posttreatment photographs (Fig 10). The discrepancy that would exist in the gingival zeniths of the upper anterior teeth due to microdontia of the upper laterals had been explained to the patient previously. She found it esthetically acceptable and did not want build-ups or veneers. A well seated Class I molar and canine relationship had been achieved (Fig 10). The posttreatment clinical evaluation revealed no mobility of the teeth with SRA. The panoramic radiograph showed good root parallelism and root development as well as apical closure of the lower left second premolar (Fig 11). The posttreatment lateral cephalometric analysis and superimposition revealed minimal growth and maintenance of the soft tissue profile (Fig 12, Fig 13). One year after retention, facial and intraoral photographs showed a stable occlusion (Fig 14). One-year postretention IOPA radiographs were obtained for the upper first and second premolars bilaterally because they were severely affected with SRA and were subjected to the maximum orthodontic stress (Fig 15). Root resorption was measured for each of the premolars by comparing them with the initial 3-month periapical radiograph (Fig 7) by means of the technique proposed by Linge and Linge22Linge L. Linge B.O. Patient characteristics and treatment variables associated with apical root resorption during orthodontic treatment.Am J Orthod Dentofacial Orthop. 1991; 99: 35-43Abstract Full Text PDF PubMed Scopus (286) Google Scholar; the results are presented in Table II. Of the 4 premolars, the upper right second premolar showed the maximum resorption, 0.5 mm, which is within the range of clinically acceptable orthodontically induced external root resorption.17Samandara A. Papageorgiou S.N. Ioannidou-Marathiotou I. Kavvadia-Tsatala S. Papadopoulos M.A. Evaluation of orthodontically induced external root resorption following orthodontic treatment using cone beam computed tomography (CBCT): a systematic review and meta-analysis.Eur J Orthod. 2018; ([Epub ahead of print])Google ScholarFig 11Posttreatment panoramic radiograph.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 12Posttreatment lateral cephalometric radiograph.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 13Superimpositions of pretreatment (black) and posttreatment (red) cephalometrc tracings.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 14Six-month follow-up facial and intraoral photographs.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 15One-year postretention periapical radiographs of the upper premolar region.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Table IIMeasurement of crown and root lengths from periapical filmsToothC1C2R1R2OIRR#47.1 mm7.0 mm6.1 mm5.5 mm0.5#56.1 mm7.1 mm6.0 mm6.5 mm0.4#126.4 mm7.5 mm6.1 mm6.7 mm0.4#136.7 mm7.4 mm5.8 mm6.3 mm0.1C1, Initial crown length (3-month radiograph); C2, final crown length (1-year follow-up radiograph); R1, initial root length (3-month radiograph); R2, final root length (1-year follow-up radiograph); OIRR, orthodontically induced external root resorption: R1 − R2(C1/C2). Open table in a new tab C1, Initial crown length (3-month radiograph); C2, final crown length (1-year follow-up radiograph); R1, initial root length (3-month radiograph); R2, final root length (1-year follow-up radiograph); OIRR, orthodontically induced external root resorption: R1 − R2(C1/C2). Molecular analysis of the gingival crevicular fluid from SRA patients has revealed that a characteristic feature is the activation, complex formation, and fragmentation of matrix metalloproteinase 9 (MMP-9). MMP-9 has low collagenolytic resorptive activity, thus reinforcing the hypothesis of developmental root shortening in SRA, which is not due to root resorption.5Apajalahti S. Sorsa T. Ingman T. Matrix metalloproteinase-2, -8, -9, and -13 in gingival crevicular fluid of short root anomaly patients.Eur J Orthod. 2003; 25: 365-369Crossref PubMed Scopus (19) Google Scholar Animal studies have also revealed that the loss of nuclear factor I genes results in root shortening due to disrupted odontoblast differentiation,23Park J.C. Herr Y. Kim H.J. Gronostajski R.M. Cho M.I. Nfic gene disruption inhibits differentiation of odontoblasts responsible for root formation and results in formation of short and abnormal roots in mice.J Periodontol. 2007; 78: 1795-1802Crossref PubMed Scopus (66) Google Scholar which could lead to future investigative research on the possible biologic basis of SRA in humans. Although unable to clearly delineate the exact inheritance pattern for SRA, studies have established a hereditary and genetic predisposition.4Puranik C.P. Hill A. Henderson Jeffries K. et al.Characterization of short root anomaly in a Mexican cohort—hereditary idiopathic root malformation.Orthod Craniofac Res. 2015; 18: 62-70Crossref PubMed Scopus (13) Google Scholar, 7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar Furthermore, SRA has been associated with other dental anomalies, such as tooth agenesis, ectopic canines, and peg-shaped laterals leading to further evidence for the existence of a shared genetic mechanism.2Apajalahti S. Holtta P. Turtola L. Pirinen S. Prevalence of short-root anomaly in healthy young adults.Acta Odontol Scand. 2002; 60: 56-59Crossref PubMed Scopus (43) Google Scholar, 7Apajalahti S. Arte S. Pirinen S. Short root anomaly in families and its association with other dental anomalies.Eur J Oral Sci. 1999; 107: 97-101Crossref PubMed Scopus (43) Google Scholar Previous case reports outlining the management of patients with SRA have used different treatment strategies to minimize the potential complications due to orthodontic forces. Marques et al managed a patient with SRA by specifically addressing the skeletal discrepancy and minimizing orthodontic tooth movement to meet the requirements of the case.24Marques L.S. Generoso R. Armond M.C. Pazzini C.A. Short-root anomaly in an orthodontic patient.Am J Orthod Dentofacial Orthop. 2010; 138: 346-348Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar In our patient, on the other hand, SRA was associated with dental anomalies such as ectopic and impacted teeth, thus necessitating the use of orthodontic forces. Treatment of multiple impacted teeth is challenging and time consuming even under normal circumstances.20Becker A. Chaushu G. Chaushu S. Analysis of failure in the treatment of impacted maxillary canines.Am J Orthod Dentofacial Orthop. 2010; 137: 743-754Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar SRA of the impacted teeth and teeth adjacent to the ectopic/impacted teeth led to an added complexity in the present patient. The initial step for such cases should be to determine the correct diagnosis through a thorough patient history and available evidence. In our case, once the diagnosis of SRA was confirmed and the risks communicated to the patient and the parents, an individualized treatment approach was constructed and delivered. The decision to monitor the root resorption of the teeth with SRA before bonding all teeth was made based on previously published orthodontic literature.1Lind V. Short root anomaly.Scand J Dent Res. 1972; 80: 85-93PubMed Google Scholar, 2Apajalahti S. Holtta P. Turtola L. Pirinen S. Prevalence of short-root anomaly in healthy young adults.Acta Odontol Scand. 2002; 60: 56-59Crossref PubMed Scopus (43) Google Scholar, 14Valladares Neto J. Rino Neto J. de Paiva J.B. Orthodontic movement of teeth with short root anomaly: should it be avoided, faced or ignored?.Dental Press J Orthod. 2013; 18: 72-85Crossref PubMed Scopus (14) Google Scholar Although orthodontic treatment is not contraindicated, the root form and orthodontic stress patterns postulate an increase in root resorption potential in teeth with SRA.18Oyama K. Motoyoshi M. Hirabayashi M. Hosoi K. Shimizu N. Effects of root morphology on stress distribution at the root apex.Eur J Orthod. 2007; 29: 113-117Crossref PubMed Scopus (47) Google Scholar, 19Thongudomporn U. Freer T.J. Anomalous dental morphology and root resorption during orthodontic treatment: a pilot study.Aust Orthod J. 1998; 15: 162-167PubMed Google Scholar Therefore, we followed the recommendations suggested by Valladares et al and used light forces throughout the treatment, allowed longer intervals between activations, and performed periodic monitoring with radiographs.14Valladares Neto J. Rino Neto J. de Paiva J.B. Orthodontic movement of teeth with short root anomaly: should it be avoided, faced or ignored?.Dental Press J Orthod. 2013; 18: 72-85Crossref PubMed Scopus (14) Google Scholar The other decision that was made after considerable deliberation and discussion with the periodontist was the exposure of the impacted lower left second premolar which most likely had SRA but the apical third of the root was still forming. Longitudinal follow-up of tooth movement with partially formed roots has shown favorable results,25da Silva Filho O.G. Mendes Ode F. Ozawa T.O. Ferrari Junior F.M. Correa T.M. Behavior of partially formed roots of teeth submitted to orthodontic movement.J Clin Pediatr Dent. 2004; 28: 147-154Crossref PubMed Scopus (4) Google Scholar but there is a scarcity of literature on exposure and orthodontic traction of teeth with incomplete root formation. Some published reports recommend waiting for spontaneous eruption owing to a great amount of variability in the formation and eruption of second premolars in general.26Bicakci A.A. Doruk C. Babacan H. Late development of a mandibular second premolar.Korean J Orthod. 2012; 42: 94-98Crossref Scopus (7) Google Scholar, 27Da Silva Filho O.G. Lauris Rde C. Ferrari J.F. Ozawa T.O. Delayed development of a maxillary left second premolar.J Clin Orthod. 2002; 36: 291-295Google Scholar We decided to carefully expose the lower left second premolar and place gentle orthodontic forces on it to simulate natural tooth eruption based on the scientific evidence that hypothesizes the existence of commonalities in the genetic expression and the end results of the 2 processes.28Wise G. King G. Mechanisms of tooth eruption and orthodontic tooth movement.J Dent Res. 2008; 87: 414-434Crossref PubMed Scopus (367) Google Scholar The stepwise mechanics for orthodontic traction was planned with the use of the CBCT images. After an initial mesial force to move the crown of the tooth away from the molar root, a cantilever was designed in such a way that it applied a mesial, buccal, and extrusive force on the premolar. The use of a cantilever from the first molar can easily generate a single light force for eruption of the impacted lower left second premolar because the line of action, the magnitude, and the point of force application can be titrated by the clinician. In our case, a cantilever was made from 0.017 × 0.025-inch Connecticut New Archwire generating a force of 20 cN. From a buccal view, the applied force (F1) can be resolved into vertical (FV) and horizontal (FH) components, which mesialized and extruded the premolar (Fig 16). From an occlusal view, the traction force can be divided into mesiodistal (FM) and buccolingual (FB) components, which provided mesial and buccal traction to the premolar. Because this system is in equilibrium, there are distal, intrusive, and constrictive forces on the first molar. The equilibrium forces that were generated on the first molar were dissipated among all other mandibular teeth attached to the rigid main archwire. Small reactivations of the cantilever as the tooth erupted led to its gradual eruption into the oral cavity over a period of 7 months. The root formation also proceeded to completion during this period, attaining the same crown-to-root ratio as the contralateral premolar. Future studies may conclusively substantiate the presence or absence of resorptive susceptibility for teeth with SRA. Genetic studies are also needed to be able to accurately diagnose the anomaly in the future. However, as the present case demonstrates, as well as based on the evidence in previously published literature, it is possible to narrow down the diagnosis of patients with SRA. We used conventional mechanics to treat the patient, although precautionary alternate plans, prudent mechanics, and continuous monitoring with the use of periodic radiographs were incorporated into the treatment plan. We also recommend simplification of the force system, such as the use of the cantilever system as an ideal approach for orthodontic traction, as demonstrated by this case. The execution of a well defined plan resulted in successful and efficient treatment of impacted teeth in a patient with SRA. Favorable esthetic and functional results were also obtained. Judicious weighing of risks and benefits before commencing treatment is recommended because each case of SRA will pose unique challenges to the clinician. Finally, we emphasize the need for correct diagnosis to achieve a successful outcome with minimal adverse effects.
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