## 4 Discussion
The overall change in overbite was about 5.1 mm, from an initial open bite of \(-\)3.9 mm to a final overbite of 1.2 mm. In the anteroposterior dimension, TAD-based maxillary posterior intrusion produces counterclockwise mandibular autorotation that increases the chin projection and improves the facial profile in class II patients [9, 14, 15]. In our case, the mandibular plane angle became slightly decreased with the mandibular autorotation, which contributed to a more relaxed lower lip closure. We also maintained the vertical position of the mandibular posterior teeth, performed IPR at the mandibular teeth and used CL III elastics from the mandibular teeth to the maxillary TADs. As a result, the mandibular incisors were retracted and retroclined. Such changes in the anteroposterior dimension subsequently impacted the vertical dimension positively, as evident by the rotation of the occlusal planes and OB improvement. In the transverse dimension, buccal crown tipping of the posterior teeth is an adverse side effect that needs to be counteracted using, for example, a TPA or palatal TADs [9, 15]. In our case, and despite using stiff rectangular sectional archwires relative to the bracket slot, we encountered such a side effect due to the use of a commercially available removable TPA that lacked proper stiffness. Buccal crown tipping of the posterior teeth in our case was later managed with cross elastics on lighter sectional upper archives against a larger and stiffer continuous lower archwire. For a systematic comparison between the present report and previous studies with (dis)similar intervention and retention strategies, it is beneficial to use the Pyramid of Orthodontic-Periodontal Planning described in a previous publication [16]. The pyramid is classified into six sequential steps of customized planning and treatment of periodontally involved patients. The pyramid is used (implicitly) by most studies in the scientific dental literature [3, 17, 18, 19, 20, 21], and the steps described next are not necessarily ordered according to their importance [16]. The first step includes pre-orthodontic attainment of a stable and healthy periodontium, which includes oral hygiene instructions, scaling and root planning, as well as possible antibiotic prescription and/or flap surgery [20, 21]. This is to be followed by a strict periodontal observation period ranging from 2 to 6 months to allow time for the restoration of health, remodeling of periodontal tissue and assessment of the patient's compliance [3, 21]. Others have recommended the need for a pre-orthodontic clearance letter from the periodontist confirming the patient's readiness for orthodontic treatment [16]. Also, a program of regular periodontal follow-up visits during orthodontic treatment should be scheduled and implemented [1, 20]. Our patient was treated by her periodontist with the provision of oral hygiene instructions, scaling and root planning. She was monitored by her periodontitis for 4 months before the provision of formal documentation of her readiness for orthodontic movement. For our patient, the observation period extended to the initial phase of active limited orthodontic treatment with the placement of only removable TPAs and LLHAs, with soldered spurs. She also attended a periodontal follow-up every 3 months during orthodontic treatment, which was essential in preventing further alveolar bone loss and providing stable support tissues during and after orthodontic treatment [15, 19]. Under an overarching theme of biomechanics, the second, third and fourth steps include planning for anchorage, biomechanics and intrusion movement. The typical presentation of periodontally involved patients includes reduced alveolar support, pathological migration, proclination of maxillary incisors, spacing and supra-eruption, which compromise function and esthetics [1].