Introduction

Class III dysmorphosis is one of the most difficult dento‐craniofacial alterations to resolve. Most subjects presenting such dysmorphisms show skeletal and dentoalveolar component alterations. Class III deformities, by definition, are those due to some combination of maxillary deficit and mandibular excess (Proffit and Henry, 2001; Proffit et al., 2004).

Clinical situations whose orthodontic treatment primary goal is the skeletal Class III orthognathic decompensation may displace the roots outside the original bony structure.

Orthognathic surgery has seen remarkable improvements in its planning and technique since its initial conception (Steinhauser, 1996). These improvements include better preoperative treatment planning setups (Bell et al., 1985; Rossini, 2017), digital planning using intraoral scanners and cone‐beam computed tomography (CBCT) (Swennen et al., 2009), intraoperative techniques for fixation and positioning (Taub and Palermo, 2017), and presurgical orthodontic mechanical support, creating a more fluid transition for orthognathic cases (Kankam et al., 2019).

Conventional orthodontic treatment requires the elimination of dental compensation. Decompensation means flaring the incisors in skeletal Class III, where lower anterior teeth are lingually inclined. In these patients, the symphysis is often very thin and elongated. Hence, the risk of detrimental periodontal side effects, such as resorption of the buccal plate, the thinning of the overlying gingiva, or both, is very high (Choi et al., 2015). Several studies have shown that regenerative corticotomy (RC) (also known as periodontally accelerated osteogenic orthodontics [PAOO^®]) has the power of counteracting the marginal bone resorption when the root is forced outside the alveolar bone, both in conventional treatment (Wilcko et al., 2009; Brugnami and Caiazzo, 2014) and in orthognathic cases (Kim et al., 2011; Ahn et al., 2012; Coscia et al., 2013; Wang et al., 2013, 2014; Ahn et al., 2016).

The recent technological innovations have affected oral and maxillofacial surgery and orthodontics, especially with the development of transparent aligner systems (Boyd, 1999; Boyd et al., 2000; Wong, 2002; Tuncay, 2006; Rossini et al., 2015; Schupp and Haubrich, 2016).

Invisalign system (Align Technology, Inc., San Josè, California, United States) is an increasingly popular technique for aligning teeth and correcting malocclusions orthodontically (Kuncio, 2014). It consists of a series of transparent aligners that produce orthodontic movements without compromising the aesthetic.

When correctly used, transparent aligners have the unique property of allowing the movements of single teeth, which helps plan the best timing for the periodontal and surgical procedures. Timing of specific procedures can be precisely managed if the orthodontist correctly plans individual movements on individual teeth or groups of teeth using three‐dimensional (3D) design software.

In skeletal Class III cases undergoing orthognathic surgery, clear aligners and RC were combined to prevent periodontal side effects of dental decompensation.

Diagnosis and Treatment Planning

Planning a treatment that includes improving both facial aesthetics and malocclusion correction. In some cases, the dental movement (orthodontic or surgical) performed to correct the bite may have a negative impact on facial aesthetics. In addition to verifying symmetry in frontal projections, profile analysis is essential. Among the most used values is the angle of facial convexity, formed by the union of the following points: glabella–subnasal–pogonion cutaneous (any sagittal discrepancies between the two maxillae are readily appreciated) (Figure 10.1) and the nasolabial angle (Figure 10.2), formed by the intersection of the following lines: ULA‐Sn Sn‐C. Analyzing the jaws with model development provides no information regarding aesthetics but allows quantifying and defining the malocclusion. The models of the jaws, cephalometry, CT scan of the maxillofacial district, and the clinical and photographic examination should provide an accurate diagnosis.

Skeletal and dental Class III cases undergoing this type of treatment were followed by the maxillofacial surgery service of the San Filippo Neri Hospital in Rome under the Helsinki Declaration. This chapter shows cases with severe dysgnathia and candidates for orthognathic surgery; a series of clinical and instrumental procedures must be applied. These elements can help clinicians establish a correct and accurate diagnosis, quantify the malocclusion or dysgnathia, and formulate a proper therapeutic plan. Successful orthognathic procedures in Invisalign patients require effective collaboration between the surgeon and the orthodontist (Kankam et al., 2018).

The protocol includes the following phases: anamnestic and clinical examination, photographic examination, radiographic examination, dental arch model examination, cephalometric examination, surgical planning, and informed consent. In subjects with Class III malocclusion, candidates for orthognathic surgery, particular attention is paid to the individuals’ psychological motivations, aesthetic qualities, and functional and social aspects.

The clinical examination represents a fundamental moment in the diagnosis for the immediate data on the spatial position of the maxillary and mandible, especially in the phase of the therapeutic choice. All the information obtained must be evaluated and customized for the specific solution of the case under examination to achieve an aesthetic–functional restoration accepted by the patient. The anamnestic and clinical examination includes an aesthetic and occlusal evaluation that considers the 3D position of the bone structures and the intercuspation of the jaws.

Case 1

The initial clinical documentation of the 17‐year‐old patient includes extraoral and intraoral pictures (Figures 10.3–10.5).

Soft and skeletal tissue analysis is also used in the cephalometric examination for a better aesthetic evaluation. CT scan of the craniofacial district is often used with extrapolation of projections as teleradiography in lateral, posterior–anterior to perform all measurements of bone and dental structures in cephalometry (Figure 10.6). The investigation is completed with panoramics, which can always be extrapolated from CT scan. Any TMJ (temporormandibular joints) dysfunctions are detected.

During the evaluation of the two jaws and their spatial relationship in maximum intercuspation, the malocclusion, the number and alignment of the jaws of the dental elements, the over‐jet on the sagittal plane, and the over‐bite on the vertical plane, the intermolar and intercanine distances and the disharmonies between the jaw and the dental elements are precisely evaluated. The models of the jaws detected with an intraoral scanner before the surgical phase can be analyzed, and a surgical setup can be performed on them, reproducing the programmed movements of the bone bases by evaluating and programming the relationships between the two jaws at the end of the surgery (Figure 10.7).

Using all the abovementioned examinations are essential for the most suitable solution, compatible with this subject’s dental, skeletal, aesthetic, and functional framework.

Therapy Protocol

In this case, the therapeutic protocol follows a classic orthodontic–surgical treatment (presurgical orthodontics, followed by surgery, and finally, postsurgical orthodontics). Presurgical orthodontics is used to align and prepare the jaws for surgery.

Recently, instead of traditional orthodontics (with braces and wires), the authors have used the Invisalign system for orthodontic treatment. The Invisalign system could represent a suitable solution to such problems (Bishop et al., 2002; Boyd, 2007). Using its software, ClinCheck^® (Align Technology, Inc., San Josè, California, United States) (Boyd and Waskalic, 2001), it is possible to realize the entire treatment planning with a very high predictability index in dental movements to plan every single movement and to dose the orthodontic strengths respecting the periodontal tissues (Figure 10.8).

The orthodontic plan uses ClinCheck, the 3D processing of orthodontic movements. The final 3D visualization in ClinCheck is due to an intraoral scan (iTero) of the two dental jaws and a correct prescription with specific requests for dental correction in the three dimensions of the space. Cephalometric analysis at the beginning of the treatment indicated a skeletal Class III and a proclination of the upper incisors and lingualization of the lower incisors (IMPA: 76.64°).