Integrating orthodontic treatment into comprehensive treatment planning for adult patients can enhance both esthetic and functional results (Alfallaj, 2020; Kokich and Spear, 1997). However, unlike conventional orthodontics performed in young or adolescent patients, where patients present with a healthy periodontium and minimally restored dentition, it is common for adult patients to have multiple missing teeth and a periodontally and structurally compromised dentition that will require considerable reconstructive dental treatment, all of which would make orthodontic treatment more challenging (Kokich and Spear, 1997). Furthermore, one of the objectives of restorative treatment is to achieve a stable occlusal relationship on completion of the treatment, which is challenging in severe malocclusion cases if not treated orthodontically prior to restorative treatment. Therefore, the objectives of orthodontic treatment must be planned in a team setting in conjunction with a restorative dentist and other specialists to establish a proper tooth position and stable occlusal relationship that will simplify future restorations. All the specialists involved should communicate and plan the case before implementing any treatment. Also, each of them should know the specific stage at which they should intervene, the time required to accomplish the objectives of their intervention, and the costs associated with it (Alfallaj, 2020; Kokich, 2008).

For effective and more reliable management of pre‐prosthetic orthodontic cases, a diagnostic set‐up and wax‐up for future restorations are needed at the planning stage (Kokich and Spear, 1997). The orthodontist should confirm that changes in tooth position on a physical or digital diagnostic cast are achievable in the patient’s mouth, and the restorative dentists should ensure that the tooth position is suitable for future restorations that are both esthetically and functionally acceptable (Figure 19.1). Furthermore, advances in digital technology and its applications in dentistry can be used to facilitate and integrate both restorative and orthodontic treatments. Intraoral scanners and desktop scanners can be reliably and accurately used to transform the dentition to a three‐dimensional (3D) model that can be used for planning orthodontic and restorative aspects of the treatment (Cho et al., 2015; Wesemann et al., 2017). Teeth can be moved virtually, restorations designed, and then the desired treatment can be visualized on a monitor or physically through 3D printing (Figure 19.2). This application of digital technology allows for better communication between the treating dentists, an easier and faster workflow, and good estimation of the needed treatment and its intended outcomes.

Indeed, as with any conventional orthodontic treatment, patients should undergo the disease control phase before starting any orthodontic teeth movement, which includes extraction of hopeless teeth, complete removal of all factors causing gingival inflammation, correction of defective restorations, and restoration of carious lesions to achieve long‐term therapeutic goals of comfort and predictability.

Pre‐prosthodontic orthodontic treatment can be summarized as the management of excessive or limited inter‐ and intraarch restorative spaces and correction of malocclusion in order to achieve the desired functional and esthetic outcomes. While simple malocclusion cases might benefit from simple orthodontic intervention using removable orthodontic appliances prior to or during prosthodontic treatment, advanced cases of malocclusion will require more comprehensive orthodontic treatment before initiating any restorative treatment in order to provide the restorative dentist with ideal occlusion and teeth positions. On the other hand, prosthodontic treatment could precede the orthodontic treatment in order to provisionalize structurally compromised teeth and provide means for orthodontic tooth movement.

The focus of this chapter will be to discuss the rationale and procedures performed as part of pre‐prosthodontic orthodontic treatment. In brief, the following topics will be discussed in this chapter:

• Pre‐prosthetic management of intraarch spaces.
• Pre‐prosthetic management of interach spaces.
• Correction of ridge deformity though orthodontic tooth movement.
• Pre‐orthodontic prosthodontic treatment.

Pre‐prosthodontic management of intraarch spaces

Intraarch space discrepancy, either due to space deficiency such as crowding and teeth migration or due to excessive spaces such as diastema, microdontia, and missing teeth through congenital or environmental factors, is a major area of interaction between restorative dentistry and orthodontics. These patients present with compromised esthetics, difficulties in pronunciation, bone loss, reduced chewing efficiency, malocclusion problems, and negative psychosocial impact (Behr et al., 2011; Johal et al., 2022; Kokich, 2005; Polder et al., 2004; Rakhshan, 2015). The future restorative plan must be taken into consideration prior to initiating orthodontic treatment and each clinical situation must be managed accordingly. Therefore, a multidisciplinary approach is essential for a successful treatment outcome (Figures 19.3 and 19.4). It must be emphasized that moderate to severe malocclusion cases will require comprehensive orthodontic treatment before initiating the final restorative treatment in order to provide the restorative dentist with ideal tooth position and occlusion to facilitate fabrication of biologically, functionally, and esthetically satisfactory restorations (Figure 19.5). However, simple crowding cases could be managed with straightforward orthodontic intervention, such as removable orthodontic appliances with minor interproximal reduction to provide the needed space for tooth movement prior to or during prosthodontic treatment to achieve the desired esthetic, functional, and occlusal outcomes (Figure 19.6).

Congenitally missing teeth

Management of dental agenesis should be planned and initiated during adolescence while the patient is growing, which usually requires an interim treatment at around 7–9 years of age (Behr et al., 2011). Early orthodontic intervention in these cases preserves more treatment options in the future that are more predictable, and have better esthetic and functional outcomes (Kokich, 2005). Different treatment options are possible, ranging from space closure to space creation with prosthetic replacement or transplantation, depending on several occlusion factors.

Missing lower second premolar

Patients with congenitally missing second premolars can present with either a retained or an exfoliated primary second molar. Three treatment options are possible: (i) maintaining the primary second molar; (ii) extraction of the primary second molar and space closure; and (iii) extraction of the primary second molar and prosthetic replacement or auto‐transplantation. The treatment decision depends on several factors, including the patient’s age and growth potential, primary second molar condition, eruption pattern, and general space conditions (Kokich, 2005).

When the primary second molar tooth is in good condition, the patient has no arch length deficiency, and he or she does not need the extraction to treat the malocclusion, maintaining the primary second molar is the treatment of choice in order to maintain the bone vertically and buccolingually (Kokich, 2005). However, the size of the primary molar must be modified to achieve the proper occlusal relationship. A reduction of the mesiodistal width of the primary second molar to 7.5–8 mm to approximate the average width of the permanent second premolar with careful consideration of root divergence is recommended (Biggerstaff, 1992; Kokich, 2001; Sabri, 2004; Spear et al., 1997). In addition, the occlusal surface can be restored with a direct or indirect restoration to achieve proper occlusal contact (Kokich, 2005).

When the primary second molar is compromised or ankylosed, extraction is recommended. As ankylosis becomes worse with time, early extraction is recommended to avoid significant vertical bone loss and periodontal complications that could affect future implant placement (Bjerklin and Bennett, 2000; Kokich, 2005; Kokich, 2002; Kurol and Thilander, 1984). In these cases, the decision to maintain the space for future replacement or to close it depends on the overall malocclusion of the patient. If space closure is indicated, the anchorage requirements should be considered, and the use of temporary anchorage devices (TAD) might be needed (Figure 19.7).

Missing upper lateral incisor

Treatment options in cases of missing lateral incisors are either space closure with canine substitution or space opening with prosthetic replacement. Several factors must be considered in order to select the appropriate treatment option, such as the patient’s malocclusion and canine condition (Kokich, 2002). Space closure is the treatment of choice in cases that have a balanced facial profile, maxillary crowding or protrusion, Class II molar relationship with no mandibular crowding or protrusion, Class I molar relationship with mandibular crowding that requires extraction, a premolar that is suitable to substitute for a canine, or a canine that has acceptable size, shape, and color to substitute for a lateral incisor (Figure 19.8; Rosa and Zachrisson, 2001, 2007). However, communication and planning with the restorative dentist and periodontist before orthodontic treatment are vital to achieve the desired outcomes. Canines and premolars used for substitution will require modification in their height, width, thickness, rotation, gingival height, torque, and color (Table 19.1; Kokich and Spear, 1997; Kokich et al., 2011; Rosa and Zachrisson, 2007; Sharma and Sharma, 2015; Zachrisson et al., 2011). This approach, if carefully planned and executed, will result in conservative, stable, and long‐lasting esthetic results (Sharma and Sharma, 2015; Zachrisson et al., 2011).

On the other hand, if the patient does not meet the criteria for space closure, space opening and prosthetic replacement with either implant or tooth‐supported prosthesis is the alternative option (Figures 19.9 and 19.10; Sharma and Sharma, 2015). For space opening, early management during the mixed dentition is required to preserve the ridge height and width through guided permanent canine eruption into the lateral incisor space (Kokich, 2005; Kokich, 2002). When facial growth is completed and the patient is ready for prosthetic replacement, the permanent canine can be moved distally to develop an adequate buccolingual alveolar bone width for implant placement (Kokich, 2001; Kokich and Spear, 1997). Adequate implant space both coronally and apically must be determined before space opening through arrangement with the restorative dentist. Several methods are available to determine the required coronal space, like measuring the contralateral tooth size assuming it has normal morphology and size (Spear et al., 1997), Bolton analysis (Bolton, 1962), and diagnostic wax‐up, with the latter being the most predictable method (Kokich, 2005). Adequate apical space must be available between the roots of the incisor and the canine to allow for safe implant placement (Figure 19.10; Sharma and Sharma, 2015). A single tooth implant is the most conservative option for replacement, but since the implant cannot be placed until growth is completed, other options like a retainer with a pontic tooth, resin‐bonded bridge, and canine cantilever can be used temporarily to maintain the space (Kokich, 2005; Sharma and Sharma, 2015). An implant can be placed only after confirmation of facial growth cessation to avoid infraocclusion, esthetic, and periodontal issues. Several methods are available to check the vertical growth, with serial lateral cephalometric superimposition being the most accurate (Sharma and Sharma, 2015). The appropriate age varies and is estimated to be after 17 years in girl and 21 years in boys (Fudalej et al., 2007; Sharma and Sharma, 2015; Thilander et al., 1992).

Tooth migration

Even though tooth migration usually presents with both vertical and horizontal components affecting interarch and intraarch spaces simultaneously and causing occlusal plane discrepancy, this section will mainly discuss the mesio‐distal component to simplify approaching the required space management prior to the restorative treatment. On loss of interproximal contact, due to loss or extensive cavitation of the adjacent tooth, mesial tipping, tilting, or drifting of posterior teeth will occur and the available space for the future restoration will be reduced. The severity of tooth movement is both time and patient dependent; however, correction of the resulting altered space should be prosthetically driven. While simple enameloplasty could be performed to regain the reduced space and create the desired distal contact of a future implant restoration replacing the missing tooth in minor cases, more advanced situations will require greater space correction (Figure 19.2 and 19.11). Ideally, a diagnostic set‐up and diagnostic wax pattern should be made to evaluate the amount of space needed to create a restoration with favorable contours. Then, orthodontic uprighting is performed to correct the migration and create sufficient restorative mesio‐distal space for the future restoration. If this space is not corrected orthodontically, the resulting future restoration will have poor anatomical contours and the distal contact with the mesially tilted tooth will act as a food trap, creating a triangular space that is extremely difficult to clean. Also, when a fixed partial denture is the treatment of choice to replace the missing tooth, orthodontic uprighting is beneficial in correcting the angulation of a tilted abutment tooth and reducing the amount of tooth preparation needed to create a passive path of insertion between both abutments for the future prosthesis. When compared to other restorative treatment modalities to correct tilted abutments, such as locked attachments or telescopic crowns, orthodontic uprighting is less invasive, therefore it should be considered as the first treatment choice (Becker et al., 1982; Revah et al., 1985; Simon, 1984).

Pre‐prosthodontic management of interarch spaces

A short clinical crown is an often encountered problem in combined restorative and orthodontic treatments. Treatment is usually dictated by the etiological factor. Since this chapter focuses on pre‐prosthetic orthodontics, the discussion will be mainly on the management of localized worn‐down anterior teeth and management of a short clinical crown for restorative purposes.