Reason for the visit: improving the front bite and protrusion without surgery
“I was advised to have double-jaw surgery. Could orthodontic treatment alone help?”
A woman in her twenties was concerned about front teeth that bit in reverse and did not meet, as well as protrusion and asymmetry. Because she was apprehensive about surgery, she visited to find out how much improvement might be possible with non-surgical orthodontic treatment.
Before treatment
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Face and intraoral views before treatment
She had a long facial pattern with a prominent lower jaw, accompanied by both a skeletal Class III relationship and a dental Class III bite. The lower front teeth were 3 mm ahead of the upper front teeth, with a vertical gap of 2.5 mm between them. An anterior crossbite and an open bite were both present.
Particular care was needed when moving the lower front teeth backward because the supporting alveolar bone in the lower jaw was not thick. In an analysis of records from 107 adults, Handelman explained that a narrow width of alveolar bone around the lower incisors limits tooth movement and requires consideration of the risk of tissue damage.[1]
For this patient, the treatment plan therefore centered not only on how far to move the front teeth backward, but also on how to control their roots within the supporting bone.
Treatment process: upper arch expansion and use of lower extraction spaces
First, a palatal expander was used to widen the upper dental arch over approximately two months, and the appliance was then retained for about nine months. During that time, both lower first premolars were extracted and fixed orthodontic treatment proceeded with CLIPPY-C brackets.
Miniscrews on both sides of the lower jaw provided anchorage for backward movement. While closing the extraction spaces, we carefully adjusted the archwire thickness and retraction force so that the lower front teeth would not tip excessively. The emphasis was on monitoring root position and gum health, rather than on the speed of tooth movement.
After removing the palatal expander, fixed orthodontic treatment was also carried out in the upper arch to resolve crowding and coordinate the bite of the upper and lower molars.
Treatment results: improvement in anterior crossbite, open bite, and protrusion
Intraoral comparison before and after treatment
After treatment, overjet improved from -3 mm to 1.5 mm, and overbite from -2.5 mm to 2 mm. The front teeth, which had previously bitten in reverse without meeting, achieved a normal horizontal and vertical relationship. The treatment records documented a Class I bite relationship.
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<Photograph dates: August 23, 2017 – September 17, 2020>
Facial appearance and smile before and after treatment
Protrusion of the lower face was also reduced. As the dental midline improved and tension in the soft tissues around the mouth decreased during smiling, the asymmetry of the mouth corners appeared more natural. These were changes in the dentition and soft tissues, distinct from the correction of jawbone asymmetry through surgery.
Retention and follow-up
At the end of treatment, both fixed and removable retainers were provided for the upper and lower arches. Follow-up records from approximately five years after treatment showed that the bite and facial appearance remained well maintained.
Retention approximately five years after treatment
The stability of the result must also be considered when treating an open bite. In the study by Janson and colleagues, overbite was maintained more stably in the extraction group than in the non-extraction group. However, there was no significant difference in the proportion of patients with clinically significant open-bite relapse.[2] This does not mean that extraction alone can prevent relapse.
In this case, extraction spaces were used to improve the anterior crossbite and protrusion, and long-term stability was confirmed through actual follow-up records. Continued care includes wearing retainers for the prescribed amount of time and attending regular checks of the bite and gum health.
Reflections on treatment
The key to this case was not simply moving the lower front teeth backward, but carefully controlling the position and inclination of their roots within thin supporting bone. Expansion of the upper dental arch and use of the lower premolar extraction spaces helped improve both the front bite and protrusion.
The significance of treatment lies beyond the immediate changes. This case also allowed us to assess the longer-term course, with the bite and facial appearance remaining well maintained approximately five years later.
References
1. Handelman CS. The anterior alveolus: its importance in limiting orthodontic treatment and its influence on the occurrence of iatrogenic sequelae. Angle Orthod. 1996;66(2):95–109; discussion 109–110. View article
This study addresses how the width of the anterior alveolar bone relates to the anatomical limits of tooth movement. It supports the decision in this case to pay close attention to the root position and inclination of the lower incisors.
2. Janson G, Valarelli FP, Beltrão RT, de Freitas MR, Henriques JF. Stability of anterior open-bite extraction and nonextraction treatment in the permanent dentition. Am J Orthod Dentofacial Orthop. 2006;129(6):768–774. View article
This study compared 31 patients treated with extractions and 21 treated without extractions. Although overbite was maintained more stably in the extraction group, there was no significant difference in the proportion of patients with clinically significant relapse. It does not directly establish outcomes for the same combination of skeletal Class III malocclusion and lower-arch extraction treatment as in this case.
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