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Congenitally missing teeth: Orthodontic management in the adolescent patient
EARLY TREATMENT SYMPOSIUM
Congenitally missing teeth: Orthodontic management in the adolescent patient Vincent O. Kokich, Jr, DMD, MSD Tacoma, Wash
M
axillary lateral incisors are the second most common congenitally absent teeth. Two treatment options exist for treating patients with this problem. One option is to open space to replace the missing tooth; the other is to close the space and substitute the canine for the missing lateral incisor. Selecting the appropriate treatment plan depends on the malocclusion, the tooth-size relationship, and the size and esthetics of the canine. Implants have become the restoration of choice for most patients when the treatment option is to open space. Unfortunately, implants cannot be placed until facial growth is complete. Therefore, it is important to monitor eruption and implant site development from an early age. This raises many interesting questions such as: How much space is necessary? What can be done in the mixed dentition to appropriately develop a future implant site? How will the gingival architecture be affected in the area of the missing tooth? The orthodontist must answer these questions when planning treatment for patients in the mixed dentition. In opening space, the main concern is alveolar ridge width in the area of the missing lateral incisor. Alveolar ridge width may be influenced in the mixed dentition during the eruption of the permanent canine. The ideal situation is to encourage the canine to erupt adjacent to the permanent central incisor. After the canine has Affiliate assistant professor, Department of Orthodontics, School of Dentistry, University of Washington, Tacoma. Presented at the International Symposium on Early Orthodontic Treatment, February 8-10, 2002; Phoenix, Ariz. Am J Orthod Dentofacial Orthop 2002;121:594-5 Copyright © 2002 by the American Association of Orthodontists. 0889-5406/2002/$35.00 ⫹ 0 8/1/124174 doi:10.1067/mod.2002.124174
594
erupted, it can be moved distally into its normal position. By moving the tooth distally, bone is laid down, forming an alveolar ridge with adequate buccolingual width to facilitate proper implant placement.1 Occasionally, the canine does not erupt adjacent to the central incisor. When this occurs, a future bone graft might be necessary to establish the appropriate width in the edentulous area to place an implant. What if the patient is in the mixed dentition and has a large diastema between the permanent central incisors? In this instance, the centrals occupy over half of the natural lateral incisor position, and when they are moved mesially and the diastema is closed, there will probably be good alveolar width for a future implant. However, this type of movement in an adult will affect papilla heights on the distal of the central incisors as the teeth are moved toward each other. According to Atherton,2 the distal sulcus will be everted as the space is closed, leaving the papilla behind. As the nonkeratinized gingiva is exposed, the tissue looks red. Over time, this tissue will keratinize, but the location of the papilla will not change. In an adult patient, this can be an esthetic dilemma for the periodontist and the restorative dentist when placing the implant and replacing the missing tooth. Fortunately, in the mixed dentition, as the child continues to grow and the teeth erupt, the bone and the gingiva constantly change. As a result, the future esthetics of the implant site do not seem to be affected. The mandibular second premolar is another common congenitally missing tooth. Maintaining this space is often important, especially when an implant is planned for the future; the primary second molar can be an ideal space maintainer. However, this tooth will occasionally become ankylosed. Fortunately, this is a relatively uncommon occurrence, and it is often diagnosable in the mixed dentition as these teeth begin to submerge below the level of the occlusal plane. Unfortunately, this may result in a bony defect between the primary molar and the adjacent permanent teeth, which may ultimately affect future implant placement. How
Kokich 595
American Journal of Orthodontics and Dentofacial Orthopedics Volume 121, Number 6
can this problem be detected early, and what should be done in the mixed dentition to facilitate future periodontal and restorative treatment? The orthodontist must remember that the crowns of the primary molars are naturally shorter than those of the adjacent permanent first molar. Therefore, a step in the occlusal plane does not indicate that a primary molar is ankylosed. Certain methods of detection, such as tapping the tooth to determine a difference in sound, generally do not predict ankylosis. The best method to determine true ankylosis of the primary molar is by evaluating the interproximal bone level on a bitewing radiograph. If the interproximal bone level is flat, the tooth is probably erupting at the same rate as the adjacent permanent tooth. If the radiograph shows a developing vertical defect between the primary and the permanent teeth, then the tooth is ankylosed and may need to be extracted before the defect worsens. Unfortunately, extracting an ankylosed primary molar is often a difficult procedure that might require a flap as well as bone removal. The ultimate result could be a narrow ridge buccolingually that requires future bone grafting to achieve successful implant placement. Age, gender, and presence of a permanent successor ultimately influence the decision to extract an ankylosed primary molar. What if a 14-year-old girl has a submerged primary second molar, and the succedaneous second premolar is congenitally absent? Should the primary tooth be extracted? This decision should be based on the patient’s remaining facial growth. As a child grows, the rami lengthen; this causes the posterior teeth to erupt to maintain occlusion.1 This affects a 14-year-old boy more than a girl, because boys generally continue to grow until they are 18 years or older. Therefore, ankylosis in a 14-year-old girl with little remaining facial growth will have minimal effect on the occlusion. The primary tooth can be maintained but will most likely need to be reduced mesiodistally and temporarily restored into a more ideal occlusion. A 14-year-old boy with an ankylosed primary second molar and no permanent second premolar will require extraction of the primary tooth because he will continue to grow throughout adolescence. This will allow the edentulous alveolar ridge to move occlusally as the adjacent teeth erupt.3 Donnelly and Swoope4 showed that as the periosteum is stretched over the edentulous ridge, osteoblastic activity is stimulated to
lay down bone and promote alveolar ridge development. What if the succedaneous second premolar is present? Should an ankylosed primary molar be extracted? This depends on age as well as location and stage of root development of the premolar. A-9-yearold with an ankylosed and submerged primary second molar and a premolar with one-third root formation might eventually experience a significant effect on the occlusion because of the ankylosed tooth. Therefore, it might be better to extract the tooth and maintain the space until the premolar root development is complete and the tooth erupts naturally. An 11-year-old with initial radiographic evidence of ankylosis will exhibit further root formation and significant root resorption of the primary tooth. In this instance, the orthodontist might choose to wait until the ankylosed tooth exfoliates by normal eruption of the premolar.5 Orthodontists commonly encounter patients with congenitally missing maxillary lateral incisors and ankylosed mandibular primary second molars. Treatment decisions must be based on eruption pattern, age, gender, and presence of a permanent tooth. If the patient is missing the maxillary lateral incisors, guided eruption and ridge development are critical. Early diagnosis and treatment of ankylosed primary second molars also might be important to the future periodontal and restorative treatment of the adolescent. Therefore, monitoring these patients in the mixed dentition is essential to preserve various treatment options in the future.
REFERENCES 1. Kokich VG. Managing orthodontic–restorative treatment for the adolescent patient. In: McNamara JA, Brudon WL, editors. Orthodontics and dentofacial orthopedics. Ann Arbor (Mich): Needham Press; 2001. p. 423-52. 2. Atherton JD. The gingival response to orthodontic tooth movement. Am J Orthod 1970;58:179-86. 3. Ostler MS, Kokich VG. Alveolar ridge changes in patients congenitally missing mandibular second premolars. J Prosthet Dent 1994;71:144-9. 4. Donnelly MW, Swoope CC. Periosteal tension in the stimulation of bone growth in the mandible [thesis]. Seattle: University of Washington; 1973. 5. Kurol J, Olson L. Ankylosis of primary molars: a future periodontal threat to the first permanent molars? Eur J Orthod 1991;13: 404-9.
Congenitally missing teeth: Orthodontic management in the adolescent patient Vincent O. Kokich, Jr, DMD, MSD Tacoma, Wash
M
axillary lateral incisors are the second most common congenitally absent teeth. Two treatment options exist for treating patients with this problem. One option is to open space to replace the missing tooth; the other is to close the space and substitute the canine for the missing lateral incisor. Selecting the appropriate treatment plan depends on the malocclusion, the tooth-size relationship, and the size and esthetics of the canine. Implants have become the restoration of choice for most patients when the treatment option is to open space. Unfortunately, implants cannot be placed until facial growth is complete. Therefore, it is important to monitor eruption and implant site development from an early age. This raises many interesting questions such as: How much space is necessary? What can be done in the mixed dentition to appropriately develop a future implant site? How will the gingival architecture be affected in the area of the missing tooth? The orthodontist must answer these questions when planning treatment for patients in the mixed dentition. In opening space, the main concern is alveolar ridge width in the area of the missing lateral incisor. Alveolar ridge width may be influenced in the mixed dentition during the eruption of the permanent canine. The ideal situation is to encourage the canine to erupt adjacent to the permanent central incisor. After the canine has Affiliate assistant professor, Department of Orthodontics, School of Dentistry, University of Washington, Tacoma. Presented at the International Symposium on Early Orthodontic Treatment, February 8-10, 2002; Phoenix, Ariz. Am J Orthod Dentofacial Orthop 2002;121:594-5 Copyright © 2002 by the American Association of Orthodontists. 0889-5406/2002/$35.00 ⫹ 0 8/1/124174 doi:10.1067/mod.2002.124174
594
erupted, it can be moved distally into its normal position. By moving the tooth distally, bone is laid down, forming an alveolar ridge with adequate buccolingual width to facilitate proper implant placement.1 Occasionally, the canine does not erupt adjacent to the central incisor. When this occurs, a future bone graft might be necessary to establish the appropriate width in the edentulous area to place an implant. What if the patient is in the mixed dentition and has a large diastema between the permanent central incisors? In this instance, the centrals occupy over half of the natural lateral incisor position, and when they are moved mesially and the diastema is closed, there will probably be good alveolar width for a future implant. However, this type of movement in an adult will affect papilla heights on the distal of the central incisors as the teeth are moved toward each other. According to Atherton,2 the distal sulcus will be everted as the space is closed, leaving the papilla behind. As the nonkeratinized gingiva is exposed, the tissue looks red. Over time, this tissue will keratinize, but the location of the papilla will not change. In an adult patient, this can be an esthetic dilemma for the periodontist and the restorative dentist when placing the implant and replacing the missing tooth. Fortunately, in the mixed dentition, as the child continues to grow and the teeth erupt, the bone and the gingiva constantly change. As a result, the future esthetics of the implant site do not seem to be affected. The mandibular second premolar is another common congenitally missing tooth. Maintaining this space is often important, especially when an implant is planned for the future; the primary second molar can be an ideal space maintainer. However, this tooth will occasionally become ankylosed. Fortunately, this is a relatively uncommon occurrence, and it is often diagnosable in the mixed dentition as these teeth begin to submerge below the level of the occlusal plane. Unfortunately, this may result in a bony defect between the primary molar and the adjacent permanent teeth, which may ultimately affect future implant placement. How
Kokich 595
American Journal of Orthodontics and Dentofacial Orthopedics Volume 121, Number 6
can this problem be detected early, and what should be done in the mixed dentition to facilitate future periodontal and restorative treatment? The orthodontist must remember that the crowns of the primary molars are naturally shorter than those of the adjacent permanent first molar. Therefore, a step in the occlusal plane does not indicate that a primary molar is ankylosed. Certain methods of detection, such as tapping the tooth to determine a difference in sound, generally do not predict ankylosis. The best method to determine true ankylosis of the primary molar is by evaluating the interproximal bone level on a bitewing radiograph. If the interproximal bone level is flat, the tooth is probably erupting at the same rate as the adjacent permanent tooth. If the radiograph shows a developing vertical defect between the primary and the permanent teeth, then the tooth is ankylosed and may need to be extracted before the defect worsens. Unfortunately, extracting an ankylosed primary molar is often a difficult procedure that might require a flap as well as bone removal. The ultimate result could be a narrow ridge buccolingually that requires future bone grafting to achieve successful implant placement. Age, gender, and presence of a permanent successor ultimately influence the decision to extract an ankylosed primary molar. What if a 14-year-old girl has a submerged primary second molar, and the succedaneous second premolar is congenitally absent? Should the primary tooth be extracted? This decision should be based on the patient’s remaining facial growth. As a child grows, the rami lengthen; this causes the posterior teeth to erupt to maintain occlusion.1 This affects a 14-year-old boy more than a girl, because boys generally continue to grow until they are 18 years or older. Therefore, ankylosis in a 14-year-old girl with little remaining facial growth will have minimal effect on the occlusion. The primary tooth can be maintained but will most likely need to be reduced mesiodistally and temporarily restored into a more ideal occlusion. A 14-year-old boy with an ankylosed primary second molar and no permanent second premolar will require extraction of the primary tooth because he will continue to grow throughout adolescence. This will allow the edentulous alveolar ridge to move occlusally as the adjacent teeth erupt.3 Donnelly and Swoope4 showed that as the periosteum is stretched over the edentulous ridge, osteoblastic activity is stimulated to
lay down bone and promote alveolar ridge development. What if the succedaneous second premolar is present? Should an ankylosed primary molar be extracted? This depends on age as well as location and stage of root development of the premolar. A-9-yearold with an ankylosed and submerged primary second molar and a premolar with one-third root formation might eventually experience a significant effect on the occlusion because of the ankylosed tooth. Therefore, it might be better to extract the tooth and maintain the space until the premolar root development is complete and the tooth erupts naturally. An 11-year-old with initial radiographic evidence of ankylosis will exhibit further root formation and significant root resorption of the primary tooth. In this instance, the orthodontist might choose to wait until the ankylosed tooth exfoliates by normal eruption of the premolar.5 Orthodontists commonly encounter patients with congenitally missing maxillary lateral incisors and ankylosed mandibular primary second molars. Treatment decisions must be based on eruption pattern, age, gender, and presence of a permanent tooth. If the patient is missing the maxillary lateral incisors, guided eruption and ridge development are critical. Early diagnosis and treatment of ankylosed primary second molars also might be important to the future periodontal and restorative treatment of the adolescent. Therefore, monitoring these patients in the mixed dentition is essential to preserve various treatment options in the future.
REFERENCES 1. Kokich VG. Managing orthodontic–restorative treatment for the adolescent patient. In: McNamara JA, Brudon WL, editors. Orthodontics and dentofacial orthopedics. Ann Arbor (Mich): Needham Press; 2001. p. 423-52. 2. Atherton JD. The gingival response to orthodontic tooth movement. Am J Orthod 1970;58:179-86. 3. Ostler MS, Kokich VG. Alveolar ridge changes in patients congenitally missing mandibular second premolars. J Prosthet Dent 1994;71:144-9. 4. Donnelly MW, Swoope CC. Periosteal tension in the stimulation of bone growth in the mandible [thesis]. Seattle: University of Washington; 1973. 5. Kurol J, Olson L. Ankylosis of primary molars: a future periodontal threat to the first permanent molars? Eur J Orthod 1991;13: 404-9.