Late diagnosis of dentoalveolar ankylosis: Impact on effectiveness and efficiency of orthodontic treatment

CASE REPORT

Late diagnosis of dentoalveolar ankylosis: Impact on effectiveness and efficiency of orthodontic treatment Lı´via Barbosa Loriato,a Andre´ Wilson Machado,a Bernardo Quiroga Souki,b and Tarcı´sio Junqueira Pereirab Belo Horizonte, Minas Gerais, Brazil Dentoalveolar ankylosis is a local etiologic factor of malocclusion that can have deleterious effects on normal dental development. Therefore, it is of paramount importance to diagnose the problem as early as possible so that interception can be performed at the correct time. This case report demonstrates the consequences of late diagnosis of dentoalveolar ankylosis and discusses its effects on development of the occlusion and how it can increase orthodontic biomechanical complexity and treatment time. (Am J Orthod Dentofacial Orthop 2009;135:799-808)

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entoalveolar ankylosis is an eruption anomaly defined as the union of the tooth root to the alveolar bone, with local elimination of the periodontal ligament. This condition can result in replacement root resorption, in which the root is substituted by bone.1 Dentoalveolar ankylosis has been described as a local factor of malocclusion.2-4 Its cause is not well defined, but it can be associated with dental trauma,5-7 metabolic disturbance,5,7 a genetic tendency, or a local deficiency in vertical bone growth.5 According to Biederman7 and Moyers,2 ankylosis in deciduous teeth is about 10 times more likely than in the permanent dentition, and twice as likely in the mandibular than in maxillary arch. A higher incidence can be observed in the molar region during the deciduous and mixed dentition. The incidence of deciduous-tooth dentoalveolar ankylosis was reported to be 1.5% to 9.9%.8 When dental ankylosis occurs early, it is more likely to have a deleterious impact on the occlusion.7,9 The most common consequences are progressive infraocclusion of the ankylosed teeth, inclination of adjacent teeth, bone defects, and impaction of the succeeding perma-

From the Department of Orthodontics, School of Dentistry, Pontifı´cia Universidade Cato´lica, Belo Horizonte, Minas Gerais, Brazil. a Postgraduate student. b Associate professor. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Lı´via Loriato, Av. Nossa Senhora da Penha, 570/802, Praia do Canto, Vito´ria, Espı´rito Santo, Brazil 29055-130; e-mail, lbloriato@yahoo. com.br. Submitted, December 2006; revised, March 2007; accepted, April 2007. 0889-5406/$36.00 Copyright Ó 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2007.04.040

nent teeth or eruption delay.9 Becker and KarneiR’em10-12 also added midline shift to the ankylosed side and extrusion of the antagonist tooth, increasing the risk of occlusion problems. Kofod et al6 pointed out that, in a growing child, the ankylosed tooth does not follow the normal vertical growth of the alveolar process, and a deficiency occurs, causing the tooth to be even more impacted. Diagnosis of dental ankylosis is generally established through clinical findings, but radiographs can sometimes add some information. As suggested by Mullally et al,8 although a clinical diagnosis can be made by infraocclusion, percussion, and mobility testing, sometimes lack of orthodontic movement can confirm the diagnosis. Since dentoalveolar ankylosis can cause deleterious effects on occlusal development, early diagnosis and an effective treatment plan are fundamental to prevent further eruption deviations and more severe malocclusion. Our aim in this article was to present a patient in the mixed dentition with dentoalveolar ankylosis of a deciduous molar in which the diagnosis was not made at the correct time, resulting in a severe malocclusion. As a result, when the diagnosis was established, longer and more complex treatment was necessary. Although the treatment was effective, it was not efficient because of its long duration and biomechanical complexity, caused by the late diagnosis. DIAGNOSIS AND ETIOLOGY

A boy, aged 9 years 10 months, of mixed ethnic background (black and white), was referred to the orthodontic clinic of the School of Dentistry of the Pontifı´cia Universidade Cato´lica de Minas Gerais in Brazil. His chief complaints were absence of a mandibular 799

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Fig 1. Pretreatment facial photographs.

Fig 2. Pretreatment intraoral photographs.

deciduous molar and inclination of the adjacent teeth (Figs 1-5). His medical and dental histories were uneventful. The facial analysis showed symmetry, a convex profile, and good balance between the facial thirds, with an increased lower facial height. The intraoral examination showed that he was in the mixed dentition, with the permanent incisors and first molars already in the arches. In addition, he had a deep overbite and some diastemas in the anterior

region of the maxillary arch. The molars on the left side were in a Class I relationship, whereas the mandibular right first permanent molar was lingually and mesially inclined. The mandibular right second deciduous molar was missing. The panoramic radiograph showed the infraocclusion of the mandibular right second deciduous molar, indicating dentoalveolar ankylosis. The alveolar process in this region had a severe deficiency in vertical development. The permanent successor germ was developing

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Fig 3. Pretreatment models.

Fig 4. Pretreatment panoramic radiograph.

apically, between the ankylosed deciduous roots. Cephalometrically, the sagittal and vertical skeletal patterns were within normal standards, according to the analysis of Sassouni.13 TREATMENT OBJECTIVES

Phase 1 treatment (interceptive approach) was designed to begin with uprighting the mandibular right first permanent molar, followed by extraction of the mandibular right second deciduous molar and space

Fig 5. Pretreatment cephalometric tracing.

management. Phase 2 (corrective approach) objectives were to obtain the correct alignment, leveling, and dental intercuspation with fixed appliances. In addition, the patient’s facial characteristics should be maintained without altering the dentofacial growth pattern by using different orthodontic mechanics.

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Fig 6. Progress intraoral photographs.

Fig 8. Lip bumper maintenance during treatment. Fig 7. First progress panoramic radiograph. TREATMENT ALTERNATIVES

The major concerns in planning for this patient were the unfavorable position of the mandibular right first permanent molar and the impaction of the mandibular right second premolar. Considering this diagnosis, the first step in interceptive treatment would be to upright the mandibular right first permanent molar and extract the mandibular right second deciduous molar to allow the eruption of its permanent successor. This goal was accomplished with a lip bumper combined with Class III elastics on the right side and highpull headgear to minimize the unwanted mesial forces on the maxillary arch. It is a simple and effective alternative to uprighting the permanent molar, in spite of requiring patient cooperation with the elastics and the headgear. In case of noncompliance, we would have had no benefit from these mechanics, and another alternative would have been implemented.

Fig 9. Lingual arch placement.

One alternative for removable appliances could be an active lingual arch. This system would upright the right permanent molar but could create unwanted side effects on the mandibular left permanent molar that would be difficult to control. Another option would be mechanics with fixed appliances—eg, segmented mechanics or open-coil springs, as

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Fig 10. Second premolar eruption.

well as other methods that would not require patient cooperation during the tooth uprighting. However, considering the patient’s age and his mixed dentition phase with only 1 first deciduous molar in the right side and not enough anchorage teeth, it was not the first choice for interceptive treatment. If none of these alternatives had achieved good results, we could have planned to use mini-implants or miniscrews for permanent molar uprighting. Although these have often been used recently, at the time of this treatment, we had no access to these accessories. Another problem was eruption deviation of the mandibular right second premolar. Waiting for the spontaneous eruption of this tooth after regaining the space and extracting its deciduous ankylosed tooth was the conservative alternative. It can be considered that this is the ideal approach because spontaneous eruption enhances the possibility of favorable periodontal results. If the expected result was not achieved, surgical exposure and orthodontic traction with fixed or removable appliances would be another alternative. TREATMENT PROGRESS Phase 1

The therapy began with uprighting the mandibular right first permanent molar by using a lip bumper combined with Class III elastics on the right side (Fig 6). High-pull headgear was used to counter the side effects of the elastics. To optimize this mechanical effect, a maxillary acrylic anterior biteplane was placed to disclude the posterior teeth and reduce the anterior overbite.

After a year of treatment, a more favorable position of the mandibular right first permanent molar was verified, and the patient was referred for extraction of the ankylosed deciduous tooth (Fig 7). After the surgery, the lip bumper and elastics were maintained until the mandibular right first permanent molar had reached the correct position. Next, a lingual holding arch was placed to preserve the arch perimeter (Figs 8 and 9). In this way, the mandibular right second premolar eruption was observed to be within normal standards (Fig 10). After 4.5 years, the orthodontic interceptive phase ended, and the final results were favorable (Figs 11 and 12). The patient maintained his facial and skeletal characteristics, indicating that the mechanics had no deleterious impact on the dentofacial growth pattern and suggesting that the treatment was effective. A transpalatal arch was then placed to maintain the space until eruption of the permanent dentition. Phase 2

When the permanent teeth had erupted, except the third molars, the corrective phase of orthodontic treatment began. Standard edgewise appliances with .022 x .028-in slots were bonded and combined with a maxillary biteplane to reduce the anterior overbite. The dental arches were aligned and leveled, improving intercuspation and finalizing the treatment. This was uneventful, with routine archwire sequences (Fig 13). After this phase, the fixed appliances were removed, and retention began with a removable maxillary circumferential retainer and a removable mandibular spring retainer.

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Fig 11. Intraoral photographs at the end of phase 1.

Fig 12. Cephalometric tracing at the end of phase 1.

Fig 13. Progress intraoral photographs of phase 2.

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Fig 14. Posttreatment facial photographs.

Fig 15. Posttreatment intraoral photographs. TREATMENT RESULTS

The interceptive approach corrected the malocclusion caused by the mandibular deciduous molar ankylosis. Of course, this initial orthodontic treatment phase lasted extremely long. However, the effectiveness of the phase 1 approach was good, since the interceptive objectives were obtained. At the end of phase 2, a favorable facial result was obtained with the maintenance of normal characteristics

and a pleasant smile (Fig 14). Posttreatment records showed a well-intercuspated occlusion with bilateral Class I molar and canine relationships and ideal anterior overjet and overbite (Figs 15 and 16). The final panoramic radiograph shows good dental positioning and normal periodontal health, especially in the area of the former dentoalveolar ankylosis (Fig 17). Later, the patient was referred for third molar extraction.

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Fig 16. Posttreatment models.

Fig 17. Posttreatment panoramic radiograph.

Posttreatment cephalometric evaluation according to Sassouni’s analysis13 showed maintenance of the skeletal characteristics (Fig 18); the patient’s skeletal pattern was not altered by the mechanics, except for expected growth changes (Fig 19). DISCUSSION

In this patient, late diagnosis of mandibular deciduous molar ankylosis led to several alterations, mainly

Fig 18. Posttreatment cephalometric tracing.

tooth infraocclusion, lack of growth of the alveolar process in this area, and the deviated eruption of the mandibular right first permanent molar, thus establishing a severe malocclusion in the initial mixed dentition. The mesial tipping of the first permanent molar and the distal inclination of the first deciduous molar adjacent to the ankylosed tooth can be explained, according to Becker and Karnei-R’em,10 by a local change of the

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Fig 19. Cephalometric superimposition.

transseptal fibers, which are reoriented diagonally downward in the direction to the infraoccluded ankylosed tooth. There is no consensus in the literature about the ideal time to start orthodontic treatment. According to Proffit,14 the gold standard for the right time to begin orthodontic treatment is the final phase of the mixed dentition, with early treatment started before this and late treatment after this. Some situations require early treatment; one of them is dentoalveolar ankylosis. In this way, the appropriate treatment after dentoalveolar ankylosis diagnosis should mitigate the consequences and damages caused by this alteration. Kurol9 stated that it is easier to implement early treatment, because of the shorter treatment duration and lower cost. The orthodontic interceptive approach (phase 1) is important in the process. According to Ackerman and Proffit,15 interceptive procedures are intended to eliminate interferences with the normal development of the occlusion. According to Starnes,16 phase 1 should ideally begin between the ages of 6 and 8 years. Between 7 and 9 years of age, according to Freeman,17 interception of any condition that can influence the growth pattern, tooth development, and eruption should be accomplished. In this context, Kurol9 pointed out that deviated eruption requires early diagnosis to intervene at the ideal moment and intercept the problem. It should have been done in our patient if the diagnosis was established immediately after the clinical findings. Another advantage of 2-phase treatment started in the mixed dentition is that, generally, the patient tends to be more cooperative. This characteristic was essential to the success of our case. The relatively complex mechanics and the long treatment time required the patient’s efforts and compliance with the therapy.

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Because of the late start, the interceptive approach was begun immediately after the diagnosis of this patient. The correction of the inclination and positioning of the mandibular right first permanent molar was established as a priority. A lip bumper was used with Class III elastics to upright the mandibular right first permanent molar, along with a maxillary biteplane to open the posterior bite. Celsus observed in 25 B.C. that overretention of deciduous teeth could cause displacement of developing permanent teeth.18 This calls for extraction of the deciduous tooth to allow the permanent successor to erupt into a more favorable position in the arch. In this patient, the ankylosed deciduous molar was extracted after the first permanent molar was uprighted, thus reducing the risk of damaging hard structures (teeth and bones) and adjacent soft tissues. The decision to wait until the right moment to extract the ankylosed tooth was made because of the possibility of the inclined adjacent teeth interfering with the surgical intervention.9 Radiographic follow-up showed that the spontaneous eruption of the mandibular right second premolar happened under normal conditions (Fig 10). Messer and Cline19 had also verified that an ankylosed deciduous tooth does not affect the successor’s development or crown morphology. However, contrary to the outcome in our patient, those authors described the possibility of intrabony dental rotation, leading to a lack of space. Messer and Cline19 also found greater susceptibility to periodontal breakdown, with lack of alveolar bone height and formation of periodontal pockets, especially when the ankylosed tooth was retained for a long time or when extraction was needed. However, periodontal breakdown did not occur in our patient. Becker and Shochat20 showed that extraction of an ankylosed tooth allows for recovery of the eruption process of the developing permanent successor and the development of normal root length. In some situations, however, altered morphology occurs. In our patient, no morphologic changes in the second premolar were found. After permanent molar correction, the dental position and the mandibular arch perimeter were maintained with a lingual arch, allowing the other permanent teeth to erupt and the permanent dentition to be established. If the mandibular right second premolar had not erupted spontaneously, surgery followed by orthodontic traction could have been planned. Another option for dealing with an ankylosed tooth would be restoration to create contact with adjacent teeth.7,19 However, as described by Biederman7 and Mullally et al,8 this relatively conservative and simple method is not feasible for all patients. When the

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ankylosed tooth is submucosal with considerable deficiency in the alveolar process, the restoration would have no benefit for the already established sequelae. This treatment success was partially due to the patient’s dentofacial growth pattern (Class I). Late diagnosis of dentoalveolar ankylosis of a deciduous tooth can have a fundamental impact on the effectiveness and efficiency of orthodontic treatment. An effective treatment is defined as one with satisfactory results. On the other hand, the term efficiency is applied to effective treatments that were concluded in the minimum amount of time.21 According to these guidelines, this treatment was effective, having achieved excellent dental, skeletal, and facial results, both esthetically and functionally. However, it was not efficient. The amount of time to complete phase 1 therapy was too long—more than 4 years— because of the late diagnosis and the interceptive treatment. CONCLUSIONS

This clinical case illustrates the importance of monitoring the development of dental occlusion, from deciduous dentition on, because of the risk that a late diagnosis can impact the efficiency of the orthodontic therapy, even when it does not alter its effectiveness. REFERENCES 1. Consolaro A. Reabsorc¸o˜es denta´rias nas especialidades clı´nicas. Sa˜o Paulo, Brazil: Dental Press Editora; 2002. 2. Moyers RE. Handbook of orthodontics. Chicago: Year Book Medical Publishers; 1988. 3. Proffit WR, Fields HW. Contemporary orthodontics. St Louis: C.V. Mosby; 1999. 4. Graber TM, Vanarsdall RL. Orthodontics: current principles and techniques. St Louis: C.V. Mosby; 2000. 5. Mancini G, Francini E, Vichi M, Tollaro I, Romagnoli P. Primary tooth ankylosis: report of case with histological analysis. ASDC J Dent Child 1995;62:215-9.

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6. Kofod T, Wu¨rtz V, Melsen B. Treatment of an ankylosed central incisor by single tooth dento-osseous osteotomy and a simple distraction device. Am J Orthod Dentofacial Orthop 2005;127:72-80. 7. Biederman W. Etiology and treatment of tooth ankylosis. Am J Orthod 1962;48:670-84. 8. Mullally BH, Blakely D, Burden DJ. Ankylosis: an orthodontic problem with a restorative solution. Br Dent J 1995;179:426-9. 9. Kurol J. Early treatment of tooth-eruption disturbances. Am J Orthod Dentofacial Orthop 2002;121:588-91. 10. Becker A, Karnei-R’em RM. The effects of infraocclusion: part 1. Tilting of the adjacent teeth and local space loss. Am J Orthod Dentofacial Orthop 1992;102:256-64. 11. Becker A, Karnei-R’em RM. The effects of infraocclusion: part 2. The type of movement of the adjacent teeth and their vertical development. Am J Orthod Dentofacial Orthop 1992;102: 302-9. 12. Becker A, Karnei-R’em RM. The effects of infraocclusion: part 3. Dental arch length and the midline. Am J Orthod Dentofacial Orthop 1992;102:427-33. 13. Sassouni V. Orthodontics in dental practice. St Louis: C.V. Mosby; 1971. 14. Proffit WR. Philosophy of early treatment: questions and answers. Proceedings of AAO: When to treat – making decisions: a symposium on early treatment [CD-ROM]; 2005 Jan 21-23; Las Vegas, Nev. 15. Ackerman JL, Proffit WR. Preventive and interceptive orthodontics: a strong theory proves weak in practice. Angle Orthod 1980; 50:75-87. 16. Starnes LO. Comprehensive phase I treatment in the middle mixed dentition. J Clin Orthod 1998;32:98-110. 17. Freeman JD. Preventive and interceptive orthodontics: a critical review and the results of a clinical study. J Prev Dent 1977;4: 7-14, 20-3. 18. Wienberger BW. Orthodontics: an historical review of its origin and evolution. St Louis: C.V. Mosby; 1926. Retraction in: Ackerman JL, Proffit WR. Angle Orthod 1980;50:75-87. 19. Messer LB, Cline JT. Ankylosed primary molars: results and treatment recommendations from an eight-year longitudinal study. Pediatr Dent 1980;2:37-47. 20. Becker A, Shochat S. Submergence of a deciduous tooth: its ramifications on the dentition and treatment of the resulting malocclusion. Am J Orthod 1982;81:240-4. 21. Pancherz H. Treatment timing and outcome. Am J Orthod Dentofacial Orthop 2002;121:559.