Strategic treatment planning for anterior open bite: A comprehensive approach

Abstract

Anterior open bite (AOB), characterized by the lack of vertical overlap between upper and lower anterior teeth, poses a considerable challenge in orthodontics. The condition depends on many factors that combine to render it difficult to achieve post treatment stability. AOB is commonly classified as dental, skeletal, or functional on the basis of the clinical presentation and causative factors. Traditionally, skeletal AOB necessitates surgical intervention, whereas nonsurgical approaches such as extrusion arches and the Multiloop Edgewise Archwire Technique (MEAW) can be employed in more straightforward cases. Functional appliances are reserved for situations in which a patient's growth potential offers the possibility of effectively addressing AOB. This review presents a strategic treatment approach for addressing AOB, taking into account the classification and severity of the condition. The proposed SHE framework describes the use of mini-screws (S) for anchorage and vertical control, encouragement to correct habits (H), and the utilization of extractions and elastics (E). By incorporating extra-radicular mini-screws, AOB closure is achieved through anterior retraction in extraction cases or whole arch distalization of dentition with elastics in non-extraction cases. This framework emphasizes habit correction through a regimen of oral myofunctional therapy (OMT) and habit-correcting appliances to enhance posttreatment stability. This review suggests that nonsurgical correction is viable in the majority of cases, whereas surgical intervention should be reserved for severe cases of skeletal vertical overgrowth or horizontal discrepancies.

Keywords: Anterior open bite (AOB); Extractions; Habit correction; Mini-screws; Oral myofunctional therapy (OMT); Stability.

Figure 1

Illustration of ODI, APDI, and KIX in lateral cephalometric analysis. The Overbite depth indicator (ODI) is determined by adding the angle between AB and MP (denoted as θ₁) and the angle between PP and FH (denoted as θ₂). The anteroposterior dysplasia indicator (APDI) is determined by summing the angle between PP and FH (denoted as θ₂), the angle between FH and NPg (denoted as θ₃), and the angle between AB and NPg (denoted as θ₄). KIX is an acronym for an index without a full name, calculated by dividing APDI by ODI (Note: AB represents the line connecting point A and point B, MP signifies the mandibular plane, PP denotes the palatal plane, FH refers to the Frankfort horizontal plane, and NPg refers to the line connecting nasion and pogonion.) Modified from Fatima et al.

Figure 2

Illustration of the six types of photographic open bite severity index (POSI). Modified from Huang et al. Six types of anterior open bite (POSI I to XI) are depicted through drawings derived from photographs displaying the coronal view of patients' dentition, with posterior teeth in maximum intercuspation. POSI I is defined as the absence of vertical overlapping involving 1 or 2 lateral incisors. POSI II is defined as the absence of vertical overlapping involving only 1 central incisor. POSI III is defined as the absence of vertical overlapping involving both central incisors. POSI IV is defined as the absence of vertical overlapping involving all incisors. POSI V is defined as the absence of vertical overlapping involving all anterior teeth, and POSI VI is defined as the absence of vertical overlapping extending to at least 1 premolar.

Figure 3

The SHE framework in nonsurgical treatments of AOB. This diagram illustrates the biomechanical process involved in nonsurgical AOB treatment. Four extra-radicular mini-screws (S) are inserted to act as anchorages for anterior retraction in extraction cases (E) or whole arch distalization of dentition in non-extraction cases. This corrective process involves clockwise rotation of the maxillary dentition, counterclockwise rotation of the mandible and its dentition, extrusion of anterior teeth, and intrusion of molars. These actions contribute to the closure of the open bite (CR = center of resistance. M = moment. F = force. S = mini-screw. H = habit correction. E = extraction or elastics. Ex. = extrusion. In. = intrusion.) When addressing habit correction in AOB treatment, the tongue and lips are pivotal components influencing the etiology and risk of relapse of AOB. In particular, training must focus on placing the tip of the tongue at a specified spot just posterior to the incisive papilla, with the entire body of the tongue attaching to the palatal vault. The proper resting position of the tongue is illustrated in pink in the diagram.

Figure 4

A hyperdivergent jaw relationship results in excessive tension of the muscles involved in mouth closure when in the resting position.