Non-Surgical Approach to Correct Skeletal Open-Bite Malocclusion in an Adult Patient Using Third Molar Intrusion Mechanics: A Clinical Case Report

is presented as an over-eruption of the maxillary molars. The complexity of maloc-clusion and time of treatment onset may result in open bite correction, with stability being more dif ﬁ cult to achieve. 2 Habit control during and after ﬁ xed appliance removal and patient compliance in the use of retainers is also a crucial factor. Various treatment alternatives are available in the literature ranging from simple habit control to complex surgical intervention. It includes a palatal crib, high-pull headgear, orthodontic camou ﬂ age with posterior teeth extractions, vertical chin cup, box elastics, multi-loop arch-wires (MEAW), posterior bite blocks, functional appliances, orthognathic surgery, mini-implants, mini-plates, and mag-nets, etc. 2 – 8 Paradigm is shifting in the orthodontic world with the introduction of mini screw type of temporary anchorage devices (TADs). Tiny screws can be implanted with an easy surgical procedure, increasing the potential for a better orthodontic outcome. Thus, it not only helps in anchorage demanding cases but also helps achieve control of tooth movement all in all three dimensions. A similar result could


Introduction
Around 28 to 38% of orthodontic treated patients are suffering from open-bite malocclusion. 1 Various genetic and environmental contributing factors are involved in this type of malocclusion and it is presented as an overeruption of the maxillary molars. The complexity of malocclusion and time of treatment onset may result in open bite correction, with stability being more difficult to achieve. 2 Habit control during and after fixed appliance removal and patient compliance in the use of retainers is also a crucial factor. Various treatment alternatives are available in the literature ranging from simple habit control to complex surgical intervention. It includes a palatal crib, high-pull headgear, orthodontic camouflage with posterior teeth extractions, vertical chin cup, box elastics, multi-loop archwires (MEAW), posterior bite blocks, functional appliances, orthognathic surgery, mini-implants, mini-plates, and magnets, etc. [2][3][4][5][6][7][8] Paradigm is shifting in the orthodontic world with the introduction of mini screw type of temporary anchorage devices (TADs). Tiny screws can be implanted with an easy surgical procedure, increasing the potential for a better orthodontic outcome. Thus, it not only helps in anchorage demanding cases but also helps achieve control of tooth movement all in all three dimensions. A similar result could Keywords ► skeletal open bite ► temporary anchorage devices ► maxillary molar intrusion

Abstract
Paradigm is shifting in the orthodontic world with the introduction of mini screw type of temporary anchorage devices (TADs). This clinical report shows treatment and 3year retention results of nonsurgical and extraction treatment in a 34-year-old female patient treated with maxillary molar intrusion mechanics and habit control. After 24 months of active orthodontic treatment, splendid outcomes were achieved. She presented with a chief complaint of problems in biting from her front teeth. She has a Class II skeletal and dental relationship with increased vertical proportions. Control of vertical dimension and producing autorotation of mandible were the key reasons to reduce facial convexity and improvement in profile. Treatment effects of 5 degrees of autorotation of mandible and 4 mm of maxillary molar intrusion were produced to correct pre-treatment anterior open bite of 5 mm. Based on available clinical evidence, we suggest that TADs with composite buttons on molars can be used as a valuable tool to intrude molars including wisdom teeth, and help correct the skeletal open-bite with good control without buccal tipping.
be obtained with surgery although it would increase the overall cost of treatment, exposing patients to morbidity and side effects caused by surgical procedures. This clinical report shows treatment and 3-year retention results of nonsurgical and extraction treatment in a 34-yearold female patient with the use of maxillary molar intrusion mechanics and habit control. After 24 months of active orthodontic treatment, splendid outcomes were achieved.
Case Report Diagnosis An Asian female, age 34 years and 10 months, had an anterior open bite with Class II skeletal malocclusion with insignificant medical history. Her chief complaint was "I have a problem in biting from front teeth and I do not like my smile." The tonguethrusting habit was noted during rest, swallowing, and while conversation. She has a bilaterally symmetrical face, a dolichocephalic skull shape, a convex soft tissue profile, an obtuse nasolabial angle, and incompetent procumbent lips (►Fig. 1). Adequate gingival exposure was noted on a smile. Intraoral and cast examinations (►Figs. 1 and 2) demonstrated a Class II div I incisors, Class l canine and molar relationship on the left side, and Class II canine and half unit class II molars on the right side. The upper midline was deviated 1.5 mm to right, while the lower midline coincided with the face. Overjet of 5 mm, an open bite of 5 mm, crowding of À5 mm in upper and À8 mm in the lower jaw were observed with 2 steps of occlusal planes, anterior and posterior. Bolton discrepancy of an overall mandibular excess of 2.7 mm and anterior tooth excess of 2.4 mm was measured. Gingival recession was observed on all anterior teeth in both jaws. The unilateral crossbite was observed on the left side in the segment of the upper left canine, first, and second premolars. During opening or closing of her jaws, no mandibular deviation or clicking noises were detected.
The panoramic radiograph (►Fig. 3A) showed root resorption in lower anterior teeth and mild generalized bone loss around posterior teeth. Roots of upper molars were residing inside the maxillary sinus on the left side. All third molars have fully erupted.
The cephalometric analysis (►Fig. 3B, ►Table 1) showed a Class II skeletal relationship with a high-angle vertical growth pattern. Normal upper incisors and proclined lower incisors with no chin support and procumbent lower lips were seen.
The etiology of the open-bite malocclusion appeared to be a combination of hereditary and habitual factors.

Treatment Objectives
The goals were established to achieve correction in all transverse, vertical, and anteroposterior dimensions: 1 improve facial attractiveness by reducing mentalis muscle strain and providing lips support and competency, 2 control vertical dimension and produce autorotation of mandible to reduce facial convexity, 4 control tongue thrust habit, 5 create esthetic smile arc and fuller smile with controlled gum exposure, 6 correct the constricted maxilla and unilateral crossbite, 7

Treatment Alternatives
To achieve the above objectives, two plans were discussed with the patient in the treatment planning conference. Plan A was surgical maxillary impaction, LeFort I osteotomy (segmented 3-piece) combined with fixed orthodontic treatment including extraction of all first premolars. Plan B was maxillary molars intrusion with help of TADs and bite blocks (composite buttons), placement of a transpalatal arch (to control side effects of TADs, that is, buccal tipping of molars), combined with fixed orthodontic treatment including extraction of first premolars in both jaws. Plan B was accepted by the patient. A retention plan was discussed in advance.

Treatment Progress
At the onset of treatment, the patient was referred to a periodontist for consultation and addressed the issue of a gingival recession on anterior teeth. The patient was classified with stage I, grade A periodontitis. It was decided to use minimum orthodontic forces during treatment to prevent further damage to the periodontium. In addition, the use of an interdental brush and routine scaling to keep existing periodontal pockets clean was advised to the patient. Bands were placed on the maxillary first molars and an impression has done for a transpalatal arch fabrication in a laboratory. Clearance of 2 mm was kept between arch and palate and the patient was instructed to do tongue exercises, which helped in the correction of tongue trust habit and produced maxillary molar intrusion forces (►Fig. 4). Pre-adjusted 0.022 Â 0.028" slot straight wire MBT prescription brackets were bonded in the upper arch and 0.016 MNiTi archwires were used for the initial leveling using segmental arch mechanics. Composite

Treatment Results
Post-treatment records showed that the treatment goals were successfully achieved (►Fig. 5). An esthetic smile arc, good alignment of teeth, and proper occlusal settlement Fig. 6 Post-treatment dental models. were observed. In addition, marked improvement in the patient's self-esteemed and confidence was observed. The patient's speech was improved among functionality, offering an overall great satisfaction to the patient. The facial photographs showed improvement in esthetics, from convex to straight profile without any facial surgery (►Fig. 5). Class I incisors, canine and molar relationships were established (►Figs. 5 and 6), midline deviation and the open bite were corrected with the achievement of ideal overbite and overjet. The upper arch was expanded to eliminate posterior crossbites and to ideal buccal overjet. The panoramic radiograph showed effects of maxillary molar intrusion and satisfactory root parallelism (suggest tooth # left upper second premolar, left lower canine, and right lower canine roots should go distal) with proper space in between teeth. No significant signs of additional bone or root resorption were noticed (►Fig. 7). lateral cephalometric analysis (►Table 1) and superimposition (►Figs. 8 and 9) showed skeletal changes with a forward movement of the mandible (Mac-Pog improved from À19 to À12). The intrusion of 5 mm of maxillary molars and 4 mm of a forward displacement was noticed on superimposition. Vertical anchorage was maintained throughout

Case Retention
A fixed retainer was bonded to the lingual surface of the mandibular and maxillary anterior teeth. Vacuumed formed maxillary retainer was fabricated to secure the stability of open bite treatment.

Case Discussion
Despite the advanced surgical techniques, many patients with skeletal anterior open bites are not inclined to undergo surgical treatment and are happy to go for less-invasive miniimplants placement. 6,9,10 The mini implants therapy is designed to control the maxillary vertical growth, thus promoting a counter-clockwise rotation of the mandible. Thus, it helped us to achieve a straight profile in this case without any surgical procedure. Daguchi et al indicated that intrusion of molar combined with retraction of the anterior segment favors a counter-clockwise rotation of the mandible and improves the stability of the case in contrast to performing only anterior teeth extrusion. [11][12][13] Alsafadi et al also stated that the impact of intruding the upper molars is positive and causes a mandibular rotation ranging from 1°to 4°, thus helping in chin projection and reducing the anterior facial height and the mandibular plane angle. 13 In the current case, we observed similar effects in our patient's face at end of treatment. In addition, Alsafadi et al indicated maxillary molar intrusion mechanics comes with the challenge of passive extrusion of lower molars. In our case, we have overcome this challenge with the use of composite occlusal buttons, during the finishing stage, on third molars in the mandible. 13 In general, achieving long-term stability is a key measure of treatment success. According to Goto et al, treatment of open bite involving extractions of teeth cannot provide stability because the retraction of anterior teeth violates the tongue space and have a poor effect on the airway thus disturbing normal function. 14 On the contrary, others have stated that treatment with extraction allows greater stability because the retraction associated with anchorage loss promotes bite closure. [15][16][17][18] Greenlee et al indicated good stability of both surgical (82%) and nonsurgical (75%) treatments of open bite measured by a positive overbite at 12 or more months after treatment. 19 The results in this clinical case show that extraction treatment with molar intrusion mechanics produces stable results in the treatment of open bite malocclusion (►Fig. 10).
Achieving normal function and habit control is the key to success in open bite management at any age. Habits can cause relapse after orthodontic treatment. [20][21][22][23][24] It is imperative to counsel the patient on habit control and help them achieve normal function including speech, nasal breathing, and swallowing in addition to dental and facial treatment.