Orthodontic correction of a skeletal Class III malocclusion with impacted maxillary second molars and amelogenesis imperfecta

Orthodontic correction of a skeletal Class III malocclusion with impacted maxillary second molars and amelogenesis imperfecta

orthodontic waves 65 (2006) 43–49 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/odw Case report Orthodontic correct...

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orthodontic waves 65 (2006) 43–49

available at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/odw

Case report

Orthodontic correction of a skeletal Class III malocclusion with impacted maxillary second molars and amelogenesis imperfecta Kazuaki Nishimura *, Ken Hidaka, Hideki Kitagawa, Shigemi Goto Department of Orthodontics, Aichi-Gakuin University School of Dentistry, 2-11 Suemoridori, Chikusaku, Nagoya 464-8651, Japan

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Article history:

This article describes the orthodontic treatment of a 17-year-old female patient having a

Received 21 October 2005

skeletal Class III malocclusion with impacted maxillary second molars and amelogenesis

Accepted 14 November 2005

imperfecta. We simplified the treatment mechanics of orthodontic preparation for orthog-

Published on line 3 March 2006

nathic surgery by starting the traction of impacted teeth after the operation, and we were able to operate on schedule. The present case involved amelogenesis imperfecta of hypo-


plastic enamel. However, we were able to finish orthodontic treatment without causing

Orthognathic surgery

dental enamel damage such as demineralization, white spot lesion and cracks when we

Impacted second molars

removed the edgewise appliances. A good occlusion and facial esthetics were achieved, and

Amelogenesis imperfecta

these results have been maintained for three years after completion of the active treatment. # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved.



In a case of severe skeletal Class III malocclusion with long face [1], we often have difficulty controlling the posterior movement of the molars during orthodontic preparation for orthognathic surgery. This is because of the insufficient vertical eruption space due to the discrepancy of the posterior vertical dimension. One of the most important objectives of orthodontic preparation for orthognathic surgery [2] is the stability of intercuspation including the second molars just after orthognathic surgery. However, because second molars are difficult to control sufficiently during the preoperative treatment, clinicians tend to align them to avoid cuspal interference. We report a case that was diagnosed as skeletal mandibular protrusion with impacted maxillary second molars and amelogenesis imperfecta. We considered fenestration–trac-

tion of impacted teeth before orthognatic surgery to improve stability of intercuspation. However, we applied traction to the impacted teeth after orthognathic surgery because there was lack of vertical space for erupting. Since the patient had mild amelogenesis imperfecta, we instituted to establish adequate plaque control and treated the patient by a direct bonding method.


Case history

The patient was a 17-year-old Japanese female with a severe skeletal Class III malocclusion. The chief complaint was mandibular protrusion. She had an orthodontic history of chin cap therapy from 11 to 17 years of age by her family dentist. In her family history, her father had amelogenesis imperfecta and her mother had mandibular protrusion.

* Corresponding author. Tel.: +81 52 759 2162; fax: +81 52 751 8900. E-mail address: [email protected] (K. Nishimura). 1344-0241/$ – see front matter # 2006 Elsevier Ltd and the Japanese Orthodontic Society. All rights reserved. doi:10.1016/j.odw.2005.11.002


orthodontic waves 65 (2006) 43–49

observed in the maxillary bilateral second molars (Figs. 4A and 5). Cephalometric analysis showed a skeletal Class III relationship with an ANB angle of 2.18. The size of the maxilla was small and the mandible was large and protruded. FMA and gonial angle were large, indicating a high angle. In addition, the mandibular incisors showed significant lingual inclination (Table 1).


Fig. 1 – Facial photographs: (A) pretreatment (17y0m); (B) posttreatment (20y5m); and (C) postretention (23y5m).

Based on the diagnostic records, the following treatment objectives were developed: (1) lateral expansion of the maxillary dental arch, (2) correction of the deviation and prognathic appearance of the mandible, (3) surgical exposure and traction of the impacted maxillary second molars, and (4) establishment of a stable occlusion. The major treatment objective was to correct the skeletal disharmony and improve her profile with orthognathic surgery of the mandible, consisting of posterior repositioning of the mandible. However, there was a remarkable improvement in the occlusion with the eruption of the impacted maxillary second molars. Therefore, some treatment alternatives were considered. The first plan was the traction of the impacted maxillary second molars and the extraction of the third molars. The second plan was the traction of the third molars after the extraction of the impacted maxillary second molars. The third plan was the eruption of the second molars and the preservation of the third molars. From the diagnostic records, the maxillary second molars were found to have caries, and future root canal treatment was predicted to be necessary. If the prognosis of the root canal treatment were to be unfavorable, tooth extraction would have become a possibility. Therefore, the third treatment plan was selected. There was insufficient posterior vertical space for erupting the maxillary second molars. Therefore, the treatment alternative of fenestration–traction of second molars was performed after orthognathic surgery to provide adequate space for correct second molar alignment (Fig. 6).


The patient had a concave profile, with excess vertical height of the lower face (Fig. 1A). Intraorally she had an Angle Class III molar relationship bilaterally, with a minimal overbite of +0.5 mm and an overjet of 1.0 mm. The premolars and molars were positioned in crossbite. The maxillary dentition spacing was +5.6 mm and minimal crowding 1.1 mm was present in the mandibular arch. The mandibular midline shifted to the left by 1 mm to the facial one. Dental arch width of maxillary and mandibular exhibited disharmony. All erupted teeth were amelogenesis imperfecta (Figs. 2A and 3A). The panoramic radiographs showed that the maxillary left second molar was completely impacted and the maxillary right second molar was partially impacted. Caries was

Treatment plan

Treatment progress

Caries control and oral hygiene instruction were performed. Subsequently, treatment was started by lateral expansion of the maxillary arch using quad helix appliance to coordinate the changes in both maxillary and mandibular lateral widths before surgery. After correcting the posterior crossbite, edgewise appliances (0.018 in.  0.025 in.) were immediately placed on all teeth. We performed sagittal split ramus osteotomy (SSRO) 18 months after the start of the treatment. At the SSRO, the maxillary left second molar was completely impacted and the right was partially impacted as they were at the initial examination. Seven months after the surgery, the space and the antagonistic teeth were secured to apply traction to the maxillary second molars. A palatal bar was placed for

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Fig. 2 – Intraoral photographs: (A) pretreatment (17y0m); (B) posttreatment (20y5m); (C) postretention (23y5m); (D) upper central incisors pretreatment surface; and (E) upper central incisors posttreatment surface.



orthodontic waves 65 (2006) 43–49

Fig. 3 – Dental casts: (A) pretreatment (17y0m); (B) posttreatment (20y5m); and (C) postretention (23y5m).

Fig. 4 – Panoramic radiographs: (A) pretreatment (17y0m); (B) posttreatment (20y5m); and (C) postretention (23y5m).

anchorage preparation. An edgewise appliance was bonded on the buccal surfaces of the impacted teeth and started the traction after fenestration. Thirty-three months later all edgewise appliances were removed, and wrap around retainers were fabricated to maintain the alignment. Mandibular deviation and protraction were improved, and a good facial appearance was obtained. A Class I molar occlusion was achieved and both maxillary and mandibular dental midlines coincided with the facial midline. Overbite and overjet correction were achieved. The impacted maxillary

second molars were treated by full cast crown for dental caries, but they were aligned in the dental arch by orthodontic treatment (Figs. 1B, 2B, 3B and 4B). In addition, we removed edgewise appliances without damaging the surfaces of the dental enamel (Fig. 2D and E). Roots were parallel and root resorption was not detected on radiographic examination (Fig. 4B). The nANB was 2.18 preoperatively, but after active treatment it was improved to +0.18 and was stable at retention (Figs. 7–9). The patient has been in retentionformorethan36months, and theocclusion has been maintained very well during this time (Figs. 1C, 2C, 3C and 4C).

Table 1 – Cephalometric measurements Measurements Facial angle (8) Convexity (8) A-B plane (8) ANB (8) FMA (8) Gonial angle (8) Ramus inclination (8) U1-to-FH (8) FMIA (8) A0 -Ptm0 (mm) Gn-Cd (mm) Pog0 -Go (mm) Cd-Go



Pretreatment (17y6m)

Posttreatment (20y5m)

Postretention (23y5m)

84.8 7.6 4.8 3.4 28.8 122.2 2.9 111.1 58.0 48.4 119.3 77.2 62.4

3.1 5.0 3.5 1.8 5.2 4.6 4.4 5.5

92.8 4.6 2.8 2.1 34.1 140.7 16.6 114.5 79.1 45.5 131.6 84.6 57.4

90.4 1.4 0.9 0.1 33.9 136.8 12.9 116.2 70.5 45.5 127.7 82.7 56.3

90.5 1.4 0.4 0.1 33.3 137.0 13.7 113.7 74.2 45.8 127.8 81.7 57.0

2.5 4.4 3.8 4.9

orthodontic waves 65 (2006) 43–49

Fig. 5 – Periapical radiographs: pretreatment record (17y0m).

Fig. 6 – Dental casts: (A) pretreatment dental casts; and (B) set-up model after orthognathic surgery.




Orthognathic surgery and impacted teeth

Orthognathic surgery is designed to eliminate skeletal imbalance and produce sufficient profile improvement to satisfy the patient’s esthetic needs [3]. Furthermore, in a case of skeletal mandibular protrusion with long face, it is difficult


Fig. 7 – Pretreatment and posttreatment superimposed cephalometric tracing. Superimposed on the SN plane at S.

to plan a compensation treatment, such as a clockwise rotation by molar elongation for a short-faced patient, because of esthetic concerns and mechanics. Therefore, orthognathic surgery is often required [4]. Three-dimensional control of posterior movement of a molar is difficult because of the imbalance of anterior and posterior vertical facial heights. In the present case we improved the skeletal problem by orthognathic surgery at the earliest possible stage without a compensatory treatment like a clockwise rotation of the mandible. By doing so, because the patient was able to see improvements in her facial appearance, we not only obtained patient cooperation for the treatment but also effectively treated the impacted teeth. The impacted teeth were lack of vertical space for erupting. Therefore, control of the direction and power of traction became easier by starting the traction of impacted teeth after the operation, which secured the vertical eruption space. In comparison to the preoperative unstable occlusion, we were able to provide traction to the impacted teeth without producing an unwanted reaction such as lingual and buccal tipping of the anchor teeth. On the other hand, if we had started the traction before an operation, the duration of the treatment may have been shortened. The duration of postsurgical orthodontic treatment


orthodontic waves 65 (2006) 43–49

Fig. 8 – Pretreatment and posttreatment superimposed cephalometric tracing. Superimposed on the palatal plane at PNS. Superimposed on the mandibular plane at Me.

was 14 months in this case, comparable to a research reported by Satake et al. [5]. From these results, we believe that starting traction of impacted teeth after the operation led to good results. Orton-Gibbs et al. [6] reported that 99% of maxillary third molars erupt into a good or acceptable position after extraction of second molars. However, Bishara and Burkey [7] reported that one of the disadvantages of second molar extraction was frequently unacceptable positions of erupted third molars necessitating a second, late stage of fixed appliance therapy. Quinn [8] reported on some negative considerations such as small or poorly formed third molars, and the need for extended orthodontic supervision through third molar eruption. Graber [9] indicated the risk that functional disturbances can occur by extrusion of an antagonistic tooth. In the present case the maxillary second molars were given a root canal treatment for caries, and the prognosis of the teeth has been good. The selection of treatment of second molar traction without third molar extraction was accurate since the third molars have not affected the alignment.


Amelogenesis imperfecta

According to Witkop [10], amelogenesis imperfecta can be classified as hypoplastic, hypomaturation and hypocalcified

Fig. 9 – Posttreatment and postretention superimposed cephalometric tracing. Superimposed on the SN plane at S.

enamel by clinical features. Hypoplastic enamel does not develop to normal thickness. On radiographs enamel contrasts normally from dentin. Hypomaturation enamel is of normal thickness but has a mottled appearance, is slightly softer than normal enamel and chips from the crown. On radiographs enamel has approximately the same radiodensity as dentin. Hypocalcified enamel initially develops to normal thickness, is orange–yellow at eruption and consists of poorly calcified matrix which is rapidly lost, leaving dentin coarse. On radiographs enamel is less radiopaque than dentin. In the present case, on the periapical radiographs enamel contrasted normally from dentin, and the subjective symptom such as cold sensitivity to water was not found. From the above observations, we diagnosed this patient as amelogenesis imperfecta of hypoplastic enamel. We believed that the enamel would not easily chip from the crown due to mechanical irritation as in hypocalcified and hypomaturation enamel. In addition, for amelogenesis imperfecta, plaque is often retained on the rough surfaces of the dental enamel, and such patients are more prone to having dental caries. From the

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above facts, we established plaque control and decided to start treatment using a standard direct bonding method. Caries had occurred in the maxillary right second bicuspid during the orthodontic treatment. However, we believe that orthodontic treatment with a multi-bracket appliance would not be a problem for amelogenesis imperfecta of hypoplastic enamel such as in the present case. In addition, dental enamel was not extensively damaged macroscopically at the removal of multi-bracket appliances. However, it is reported that a parenchymatous defect of 10– 20 mm of tooth surface is made by etching. In such a case, a direct laminate veneer system needs to be considered in orthodontic treatment as reported by Miyazawa et al. [11].

[4] [5]


[7] [8]

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recommendations for orthognathic surgery. Am J Orthod Dentofacial Orthop 2000;118:134–40. Proffit WR. Contemporary orthodontics St. Louis: Mosby; 1986. p. 519–57. Satake H, Takagi T, Horiuchi S, Yokozeki M, Fujisawa K, Miyamoto Y, et al. Clinical statistical study of jaw deformity patients at the Department of Orthodontics, Tokushima University Dental Hospital. Shikoku Dent Res 2003;15:257– 62. Orton-Gibbs S, Victor C, Orton HS. Eruption of third permanent molars after the extraction of second permanent molars. Part 1: assessment of third molar position and size. Am J Orthod Dentofacial Orthop 2001;119:226–38. Bishara SE, Burkey PS. Second molar extractions: a review. Am J Orthod Dentofacial Orthop 1986;89:415–24. Quinn GW. Extraction of four second molars. Angle Orthod 1985;55:58–69. Graber TM. Maxillary second molar extraction in Class II malocclusion. Am J Orthod Dentofacial Orthop 1969;56:331– 53. Witkop Jr CJ. Amelogenesis imperfecta, dentinogenesis imperfecta and dentin dysplasia revisited: problems in classification. J Oral Pathol 1989;17:547–53. Miyazawa K, Miwa H, Kondo T, Goto S. Application of unique direct laminate veneer system of orthodontic treatment for prevention of caries and decalcification. Dent Jpn 2001;37:81–4.