Combining planned 3rd molar extractions with corticotomy and miniplate placement to reduce morbidity and expedite treatment. A case report with 3.5-year follow up

Abstract

Alveolar corticotomy (ACO) is increasingly popular to accelerate orthodontic tooth movement. However, because it is an invasive surgical procedure, there is still some resistance to its use. Combining ACO with other surgical procedures is a means to employ the method without adding an additional surgical intervention. Combining surgical interventions into one surgery reduces trauma and down time for the patient and also allows clinicians to maximize treatment outcomes. This article illustrates how the anticipation of the 3rd molars extraction created a window of opportunity for the use of ACO and miniplates, to successfully and efficiently retreat a moderate skeletal Class II on a young adult patient who did not accept orthognathic surgery with orthodontics as a retreatment alternative.

Introduction

The search for an ideal orthodontic anchorage method lead to the development of temporary skeletal anchorage devices (TADs). The use of miniscrews and/or miniplates represented a major advancement in orthodontics. Skeletal anchorage has important advantages over the traditional anchorage methods. It reduces the challenge of patient compliance in wearing removable appliances, it increases the number of sites available for force application, improves efficiency of orthodontic mechanics, and creates the possibility of treating some moderate skeletal malocclusions in cases where orthognathic surgery is contraindicated or unacceptable.

TADs have been used adjunctively with alveolar corticotomies (ACO) to enhance orthodontic tooth movement reducing the overall treatment time and facilitating the correction of complex malocclusions. However, despite the favorable results described in the literature, there is still some resistance to the use of ACO owing to surgery invasiveness and the costs of an additional procedure. Combining ACO with other planned surgical procedures allows for its use in cases where it would otherwise be ruled out.

Third molars extraction is one of these opportunities, since after the completion of the orthodontic treatment, approximately 75% of the patients are referred to an oral surgeon to have their 3rd molars removed. Thus, the aim of this article is to illustrate how planned surgical procedures create a window of opportunity for the rational use of ACO through a case which combines 3rd molar extractions with miniplate placement and ACO.

Case report

A 17-year-old male sought orthodontic retreatment with the following chief complaint: “I would like to know what are my options to correct my bite because it is still very bad.” He also reported that during his previous treatment he did not comply with wearing high-pull headgear (HG). Beyond that, the patient’s medical and dental history were within normal limits. We concluded that HG compliance was the primary obstacle to achieving optimal results. A strategy other than HG would be needed to address the chief complaint.

Extraoral evaluation revealed adequate facial symmetry and passive lip sealing. However, the lower facial third was moderately augmented, the profile was convex and both lips were protruded ( Fig 1 ). Study cast evaluation showed that both molars and canines presented in a Class II relationship, with an increased overjet and a reduced overbite. The transverse dimension of both arches was adequate and there was mild mandibular crowding (2 mm) ( Fig 2 ).

Figure 1
Pretreatment extraoral photographs.

Figure 2
Initial study models.

Cephalometric analysis confirmed the presence of a moderate skeletal Class II (ANB= 7°, Witts = +6 mm) and an open bite (SN-GoGn = 43°). Furthermore, protrusion and proclination of the maxillary (U1-AP = +12 mm and U1-NS = 110°) and mandibular (L1-AP = +6 mm and IMPA = 98°) incisors were observed ( Fig 3 A). The pretreatment panoramic radiograph revealed the absence of pathologies, presence of all permanent teeth and lack of space for appropriate eruption of the 3rd molars (M), which presented complete crown formation and initial stages of root development ( Fig 3 B).

Figure 3
Pretreatment radiographs.

Two treatment options were presented to the patient and his parents. The 1st option contemplated the ideal treatment objectives and consisted on the use of maxillary and mandibular fixed appliances, extraction of all 1st premolars (PM) to correct both proclination and protrusion of the incisors. These extractions would also allow to increase the overjet to create room for a subsequent mandibular advancement with orthognathic surgery that would also impact the maxilla and correct the increased skeletal vertical dimension. After thoroughly understanding the classical options, he patient and his parents rejected the surgical-orthodontics treatment plan due to the risks and morbidity associated with orthognathic surgery. At the same time, they steadfastly demanded to correct the residual malocclusion and insisted on innovative options beyond those which were made available during his first treatment.

In view of their request, the patient’s records were re-evaluated and another treatment alternative, addressing the occlusal problems and the other dental needs was suggested. Since the overall dental treatment plan anticipated 3rd molar extractions, titanium miniplate could be placed at the zygomatic arch and regional ACO from the 3rd molar to the 1st premolar area could be performed during the same surgical procedure. Subsequent intrusion of the maxillary molars and premolars, enhanced by the use of TAD’s and the ACO effects, would enable counterclockwise rotation of the mandible and consequent closure of the anterior open bite. After weighting the advantages and disadvantages of both treatment options, the patient and his parents chose this treatment alternative and signed an informed consent authorizing his treatment.

Initially, maxillary partial fixed appliances (Mini Master Series™, American Orthodontics, Sheboygan, WI) were placed bilaterally from 1st permolars to 2nd molars. Segmented leveling and alignment was performed working up to a 0.019 × 0.025-in stainless steel (SS) wire on both sides. After 5 months of posterior segmented leveling, transpalatal arches with lingual crown torque were placed on both 1st and 2nd molars to control the buccal crown inclination tendency during intrusion and the patient was referred to surgeon to have the surgical procedures performed.

For the 3rd molar extractions, intravenous sedation 5 mg of Dormonid® (Roche, Basel, BS) with 1 ml of Fentanil® (Janssen, Beerse, BE) diluted to 5 ml was implemented, and supra-apical ACO was performed only on the buccal surface of the alveolar bone on both right and left sides, extending from the mesial of the 1st premolars to the distal of the 2nd molars ( Fig 4 ). Additionally, I-shaped anchor miniplates were bilaterally implanted at the infrazygomatic crest area to support the intrusion of the maxillary molars and premolars, as well as the distal movement of the entire maxillary dentition ( Fig 4 ).

Figure 4
Surgical photographs: (A) third molar extraction sites; (B) horizontal corticotomies; (C) I-shaped miniplates inserted.

One week after surgery, intrusion was initiated with elastic chains ligating the maxillary 1st molar tubes to the miniplates’ hooks. Orthodontic check-ups took place every 2 weeks for intrusive force re-activation and after 3 months of intrusive mechanics, the anterior open bite was closed ( Fig 5 ) due to the counterclockwise rotation of the mandible. Subsequently, mandibular fixed appliances were placed and the lower crowding was corrected with interproximal enamel reduction performed on the 6 anterior teeth. Final detailing was achieved with 0.016 × 0.022-in SS wires and debonding was accomplished after a total treatment time of 14 months.

Figure 5
Progress photos: (A, B) immediately post-surgery; (C, D) three month post-surgery showing significant posterior intrusion and anterior open bite closure.

A lower fixed 3 × 3 retainer was placed and a wrap-around Hawley was inserted in the maxilla. Full-time wear of the maxillary retainer during the first 6 months post-treatment and night-time wear thereafter was requested. The post-treatment records showed that a Class I relationship was obtained for both molars and canines. Furthermore, accebtable overbite and overjet, as well as a canine-protected occlusion was achieved ( Fig 6 ). Cephalometric superimpositions confirmed the intrusion of the maxillary molars and the consequent counterclockwise rotation of the mandible ( Fig 7 ). The post-treatment panoramic radiographic evaluation revealed satisfactory root parallelism, adequate alveolar bone height and no signs of root resorption ( Fig 8 ). Finally, the 3.5-year follow-up photographs showed that the results remained stable ( Fig 9 ).

Figure 6
Final photographs.

Figure 7
Post treatment cephalometric evaluation. (A) Final ceph; (B) overall superimposition; (C) maxillary superimposition.

Figure 8
Final panoramic radiograph.

Figure 9
Intraoral photographs 3.5 years post orthodontic treatment.

Case report

A 17-year-old male sought orthodontic retreatment with the following chief complaint: “I would like to know what are my options to correct my bite because it is still very bad.” He also reported that during his previous treatment he did not comply with wearing high-pull headgear (HG). Beyond that, the patient’s medical and dental history were within normal limits. We concluded that HG compliance was the primary obstacle to achieving optimal results. A strategy other than HG would be needed to address the chief complaint.

Extraoral evaluation revealed adequate facial symmetry and passive lip sealing. However, the lower facial third was moderately augmented, the profile was convex and both lips were protruded ( Fig 1 ). Study cast evaluation showed that both molars and canines presented in a Class II relationship, with an increased overjet and a reduced overbite. The transverse dimension of both arches was adequate and there was mild mandibular crowding (2 mm) ( Fig 2 ).

Figure 1
Pretreatment extraoral photographs.

Figure 2
Initial study models.

Cephalometric analysis confirmed the presence of a moderate skeletal Class II (ANB= 7°, Witts = +6 mm) and an open bite (SN-GoGn = 43°). Furthermore, protrusion and proclination of the maxillary (U1-AP = +12 mm and U1-NS = 110°) and mandibular (L1-AP = +6 mm and IMPA = 98°) incisors were observed ( Fig 3 A). The pretreatment panoramic radiograph revealed the absence of pathologies, presence of all permanent teeth and lack of space for appropriate eruption of the 3rd molars (M), which presented complete crown formation and initial stages of root development ( Fig 3 B).

Figure 3
Pretreatment radiographs.

Two treatment options were presented to the patient and his parents. The 1st option contemplated the ideal treatment objectives and consisted on the use of maxillary and mandibular fixed appliances, extraction of all 1st premolars (PM) to correct both proclination and protrusion of the incisors. These extractions would also allow to increase the overjet to create room for a subsequent mandibular advancement with orthognathic surgery that would also impact the maxilla and correct the increased skeletal vertical dimension. After thoroughly understanding the classical options, he patient and his parents rejected the surgical-orthodontics treatment plan due to the risks and morbidity associated with orthognathic surgery. At the same time, they steadfastly demanded to correct the residual malocclusion and insisted on innovative options beyond those which were made available during his first treatment.

In view of their request, the patient’s records were re-evaluated and another treatment alternative, addressing the occlusal problems and the other dental needs was suggested. Since the overall dental treatment plan anticipated 3rd molar extractions, titanium miniplate could be placed at the zygomatic arch and regional ACO from the 3rd molar to the 1st premolar area could be performed during the same surgical procedure. Subsequent intrusion of the maxillary molars and premolars, enhanced by the use of TAD’s and the ACO effects, would enable counterclockwise rotation of the mandible and consequent closure of the anterior open bite. After weighting the advantages and disadvantages of both treatment options, the patient and his parents chose this treatment alternative and signed an informed consent authorizing his treatment.

Initially, maxillary partial fixed appliances (Mini Master Series™, American Orthodontics, Sheboygan, WI) were placed bilaterally from 1st permolars to 2nd molars. Segmented leveling and alignment was performed working up to a 0.019 × 0.025-in stainless steel (SS) wire on both sides. After 5 months of posterior segmented leveling, transpalatal arches with lingual crown torque were placed on both 1st and 2nd molars to control the buccal crown inclination tendency during intrusion and the patient was referred to surgeon to have the surgical procedures performed.

For the 3rd molar extractions, intravenous sedation 5 mg of Dormonid® (Roche, Basel, BS) with 1 ml of Fentanil® (Janssen, Beerse, BE) diluted to 5 ml was implemented, and supra-apical ACO was performed only on the buccal surface of the alveolar bone on both right and left sides, extending from the mesial of the 1st premolars to the distal of the 2nd molars ( Fig 4 ). Additionally, I-shaped anchor miniplates were bilaterally implanted at the infrazygomatic crest area to support the intrusion of the maxillary molars and premolars, as well as the distal movement of the entire maxillary dentition ( Fig 4 ).

Figure 4
Surgical photographs: (A) third molar extraction sites; (B) horizontal corticotomies; (C) I-shaped miniplates inserted.

One week after surgery, intrusion was initiated with elastic chains ligating the maxillary 1st molar tubes to the miniplates’ hooks. Orthodontic check-ups took place every 2 weeks for intrusive force re-activation and after 3 months of intrusive mechanics, the anterior open bite was closed ( Fig 5 ) due to the counterclockwise rotation of the mandible. Subsequently, mandibular fixed appliances were placed and the lower crowding was corrected with interproximal enamel reduction performed on the 6 anterior teeth. Final detailing was achieved with 0.016 × 0.022-in SS wires and debonding was accomplished after a total treatment time of 14 months.

Figure 5
Progress photos: (A, B) immediately post-surgery; (C, D) three month post-surgery showing significant posterior intrusion and anterior open bite closure.

A lower fixed 3 × 3 retainer was placed and a wrap-around Hawley was inserted in the maxilla. Full-time wear of the maxillary retainer during the first 6 months post-treatment and night-time wear thereafter was requested. The post-treatment records showed that a Class I relationship was obtained for both molars and canines. Furthermore, accebtable overbite and overjet, as well as a canine-protected occlusion was achieved ( Fig 6 ). Cephalometric superimpositions confirmed the intrusion of the maxillary molars and the consequent counterclockwise rotation of the mandible ( Fig 7 ). The post-treatment panoramic radiographic evaluation revealed satisfactory root parallelism, adequate alveolar bone height and no signs of root resorption ( Fig 8 ). Finally, the 3.5-year follow-up photographs showed that the results remained stable ( Fig 9 ).

Figure 6
Final photographs.

Jan 9, 2020 | Posted by in Orthodontics | Comments Off on Combining planned 3rd molar extractions with corticotomy and miniplate placement to reduce morbidity and expedite treatment. A case report with 3.5-year follow up
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