Porcelain rehabilitation of the maxillary arch following clear aligner orthodontic treatment

Pre-treatment assessments and evaluations

The patient had an uneventful medical history. In relation to their dental history, their home-care oral hygiene practice included toothbrushing twice daily using an electric, oscillating toothbrush with a fluoride-containing toothpaste (1400ppm NaF) and the occasional use of interproximal brushes. She was a nonsmoker and consumed fewer than 14 units alcohol per week. A summary of the primary clinical findings can be found in Table 1.

Risk assessments were also performed for dental caries, periodontal disease, oral cancer and tooth wear. Pre-operative digital scans were attained following pre-treatment clinical photographs (Figure 1). An aesthetic assessment (Table 2) was carried out followed by a full orthodontic assessment (Table 3).

Radiographs

Pre-treatment radiographs were prescribed (Figure 2). These alluded to historic endodontic treatment carried out on the UR7, UR1, UL4, UL5, UL6 and LL5. The UL4 and LL5 were also restored with a cast post and core and full coverage crown restorations. No evidence of pathological radiolucency was noted. The UL8 was also unerupted.

Diagnoses

The following diagnosis was recorded.

Planning and design

Prior to establishing a definitive treatment plan, digital orthodontic planning software, CAD/CAM smile design, and photographic manipulation were employed to present the patient with a portfolio of images, enabling them to visualize the anticipated aesthetic outcomes following treatment.

The integration of digital scanning technology with orthodontic treatment planning software facilitated the creation of an accurate video animation by Invisalign (Align Technology, AZ, USA). This animation, referred to as ‘ClinCheck,’ enables clinicians to track tooth movements and allows the patient to visualize the projected final tooth position and treatment outcomes.

Following an in-depth discussion regarding the use of Invisalign, the patient expressed a preference for this clear aligner system as their orthodontic treatment method. They were, however, made fully aware of the limitations associated with this type of orthodontic treatment, and these were reviewed during the orthodontic assessment and the formulation of a problem list (Table 4). Prior to prescribing the ClinCheck for the Invisalign technicians, treatment goals were established in collaboration with the patient, using the problem list derived from the orthodontic assessment (Table 3). Each diagnosis, the anticipated tooth movements, and the sequelae of the orthodontic treatment necessary to achieve the agreed goals were discussed in detail. This approach allowed for the establishment of realistic expectations early in the process, thereby aiding the informed consent process.

The patient's primary concern was related to contact point displacement between the upper canines and incisors (3–3). She desired that the central incisors be ‘moved forwards’ and the lateral incisors be ‘moved back’. She demonstrated flexibility regarding what could be realistically achieved with Invisalign in a minimally invasive manner, without extractions or significant changes to the occlusion. The patient was willing to accept a midline discrepancy if it meant avoiding extractions and minimizing interproximal reduction (IPR). She was also content with maintaining the current canine and molar relationships on both sides because extractions would not be required. Additionally, the potential increase in overjet and anterior open bite anticipated owing to planned expansion, was discussed, and the patient accepted these risks while being informed of the potential reduction in anterior functional contacts.

As the patient was willing to accept a compromised orthodontic treatment plan, she consented to some of the listed ‘problems’. For instance, an increase in overjet was anticipated owing to the planned buccal expansion aimed at correcting the anterior contact point displacement. However, this was to be achieved without significant interproximal reduction (IPR) or tooth extractions, which was an expected outcome, as illustrated by Figure 5.

Following the establishment of treatment goals, a prescription was formulated, and a ClinCheck was returned, detailing the necessary tooth movements to be achieved using 21 sets of aligners. This stage of the consultation was crucial, not only for securing patient consent, but also for allowing the patient to manage her expectations regarding the orthodontic treatment. The proposed pre- and post-treatment outcomes, as visualized through the ClinCheck video animation, can be observed in Figure 3.

Although the patient was aesthetically happy with the outcome proposed, reflection on the ClinCheck final tooth position is important. The initial occlusal contacts recorded by the digital scanner and used by the Invisalign technicians to plan the orthodontic treatment were identical to the patient's natural intercuspal position (ICP). Owing to poor compliance as a result of a sensitive gag reflex, it was difficult to access the distal aspect of the LL7 tooth. The final position of the proposed treatment corresponded to the problem list and prescription that was agreed with the patient. In relation to specific tooth movements proposed, there were a mixture of green, blue and black movements described by the tooth movement assessment tool, including intrusive movements on the LL4 and LR4, extrusive movements on the UL4 and UR4, as well as rotation on the UR2 and root movement on the UR3. On reflection, additional attachments should have been applied on the posterior sextants to aid anchorage and retention. IPR was not indicated in this case. No roundtripping was involved either. The upper midline was uprighted, but midline discrepancies were accepted as discussed with the problem list. Some rotational movements were required, so rather than square horizontal attachments, optimized rotational attachments were used. The aim of accepting the Class II 50% molar and canine relationship on the RHS and LHS was accepted while carrying out arch expansion. Extraction of an upper premolar may have allowed for retraction of the upper arch into Class I parameters and a normal/average overjet to be maintained. On discussion with the patient during reflection on the problem list, this route was deemed too invasive. Attachments were avoided on the ceramic restorations, including UR4, UR1, UL4, UL6 and LL5.

Once the orthodontic planning had been confirmed with a ClinCheck animation and the patient was happy to proceed, restorative planning for the upper arch porcelain restorations based on the final position of the proposed orthodontic treatment, using digital smile design software and 3D printing was carried out. This process is very similar to the analogue method of prescribing a diagnostic wax-up on a Kesling orthodontic study model. This was carried out for an enhanced consent protocol and again to set expectations early.

The digital. STL file from the final proposed position of the Invisalign orthodontic treatment was downloaded and used by the laboratory to design upper arch porcelain restorations to further enhance the patient's smile. This not only created a digital image of the designs, but also created manipulated photographs to show the patient, as well as models that could be printed and milled (Figure 4).

Treatment plan

The proposed treatment plan based on the diagnosis included the following.

Reflective overview of the treatment performed

Embarking on a comprehensive and multifaceted treatment plan, encompassing orthodontic intervention, the preparation of previously unrestored anterior teeth, and the management of a heavily restored posterior dentition, often presents a significant challenge. While initially complex, a methodical approach to treatment planning,² combined with precision in execution and pro-active communication with the dental laboratory prior to initiating treatment, proved instrumental in achieving a successful outcome. Key discussions with the laboratory team included considerations such as occlusal planning, material selection, colour matching, diagnostic wax-up and the specifics of the required tooth preparations.

An essential aspect of extensive treatment planning, as emphasized in the literature, is patient preparation and the careful alignment of patient expectations.^3,4 This is particularly relevant in cases involving orthodontic treatment, where treatment duration can be variable, and absolute timelines for tooth movement are challenging to predict. Clear communication regarding the necessity for lifelong retention, typically achieved through retainers, is critical in preventing relapse. A systematic review underscores the benefits of removable retainers over bonded retainers, owing to the increased risk of operator- and technique-sensitivity associated with bonding.⁵

In a treatment protocol extending over 18 months, managing expectations was crucial, encompassing patient motivation and a clear understanding of the treatment processes involved. Key areas discussed included anticipated outcomes of tooth whitening, shade and colour considerations, material choices, the need for provisional restorations, and balancing functional and aesthetic outcomes, particularly in full-mouth rehabilitation scenarios.

The treatment was delivered in two primary phases: orthodontic intervention and post-orthodontic restorative care, each of which is discussed in detail.

Orthodontic treatment

Upon completion of digital planning and design review, as well as the preventive and stabilization phases, and following the establishment of treatment expectations, the patient began clear aligner therapy using the Invisalign system to address anterior contact point displacement. The patient selected clear aligners to minimize the impact of treatment on daily activities and reduce visibility. Systematic reviews indicate low to moderate scientific evidence supporting aligners for non-extraction cases with mild to moderate correction needs; they have been shown to facilitate effective arch alignment through controlled tipping, rotation, intrusion, and extrusion forces.^6,7

In this case, risks associated with orthodontic therapy included several endodontically treated teeth with questionable prognoses,⁸ and extensive direct restorations necessitating cuspal coverage. Consolaro et al⁸ suggested that asymptomatic endodontically treated teeth with favourable radiographic assessments do not inherently contraindicate orthodontic intervention. The patient acknowledged the risk of potential endodontic flare-ups owing to the non-homogeneous appearance of the root fillings, particularly on LL5 and UL5, which were noted to be short of the working length. This risk, however, was considered low as the majority of orthodontic movements targeted the anterior sextant. The patient was thoroughly informed about the radiographic findings, which included non-homogeneous root fillings and incomplete fillings not extending to the apex or full working length.

A minimally invasive orthodontic approach was selected, prioritizing the maintenance of the Class II canine and molar relationships through anterior expansion and accepting a mild increase in overjet and an anterior open bite, rather than using maxillary premolar extractions and retraction of the anterior sextant.

The orthodontic treatment outcomes after 21 weeks of aligner use are shown in Figure 5, illustrating the improvements achieved. Notably, no adverse events occurred during treatment, and no symptoms were reported in relation to the previously endodontically treated teeth. The patient demonstrated a comprehensive understanding of the treatment process and fully appreciated the necessity of post-orthodontic restorative care, along with the requirement for lifetime retention to maintain optimal aesthetics. Following the removal of attachments, Essex nighttime retainers were provided to mitigate the risk of relapse.

Post-orthodontic restorative treatment

At the initial consultation, the patient raised interest in pursuing porcelain veneers as a means of providing a stable aesthetic outcome without the need for repairs owing to chipping and fracture, stain removal and the loss of lustre – risks associated with the use of composite veneer restorations.⁹ As stated in the literature, systemic reviews and meta-analysis reveal a 95.5% success rate at 10 years with feldspathic porcelain laminate veneers.^10,11,12 She was aware of the need for alignment to be carried out in a way that was as minimally invasive as possible, documented in a clinical study.¹³ Although she wanted ‘a new smile’ she wished to maintain a natural aesthetic outcome.

The porcelain rehabilitation was planned to be carried out in two phases:

On discussion with the lab technician, as well as the patient, this was the practical order that was decided, with 3 months between each phase. Once the first phase of anterior work was carried out, the anterior guidance could be determined and then used to determine the posterior sextant restorations to establish immediate posterior disclusion in lateral excursions.¹⁴

Anterior sextant rehabilitation

To ensure comprehensive clinical documentation for reflective and medicolegal purposes, a complete series of digital clinical photographs was taken (Figure 6), accompanied by pre-operative and post-orthodontic study models of the upper and lower arches. The initial phase of rehabilitation used the Kois Dento-Facial Analyser (KDFA)(Seattle, WA, USA) to orientate the maxillary cast accurately in relation to the maxilla (Figure 7). Research by Lux et al¹⁵ demonstrated that the KDFA provides maxillary cast orientation comparable to a traditional facebow when assessing incisal edge position and occlusal plane angulation.

Coordination with the laboratory confirmed no changes in vertical dimensions, and a diagnostic wax-up with canine-guided excursions was prescribed. The patient requested a ‘natural enhancement’ with porcelain restorations from upper canine to canine, aiming to retain certain features of their original smile. Specifically, the UL3 veneer was designed with a slight buccal displacement and rotation, aligned with the patient's aesthetic preferences. A digital wax-up design was created using CAD/CAM software, integrating clinical photography with. STL files for remote assessment and preapproval before resin model printing.

The wax-up designs were 3D-printed in resin, and using a putty transfer matrix (Figure 8), a bis-acryl provisional was fabricated to evaluate functional aesthetics and occlusal balance intra-orally. Following discussions with both the patient and the technician, it was decided to use feldspathic porcelain for veneers from canine to canine and layered zirconia crowns on the first premolars. Feldspathic porcelain was chosen for its minimal preparation requirement and superior aesthetics, while zirconia crowns were selected for strength and to effectively mask the dark underlying stump shades.

To transfer the desired smile design, preparations were performed under local anaesthesia, using the previously created putty stent from the wax-up, and the design was applied using bis-acryl material (Luxatemp, Englewood, NJ, USA) (Figure 9). Minimal-volume preparations were carried out using the technique described by Gürel,¹⁶ with selective removal of the UR1 veneer and the crowns on the first premolars. Given prior heavy preparations, the metal post core on UL4 and the large composite core on UR4 were retained. A combination of retraction cord for the premolars and retraction paste for the veneers was used for gingival management, aligning with systematic reviews that highlight the efficacy of both techniques.^17,18

Evidence suggests that digital workflows yield restorations with marginal adaptation comparable with, or superior to, traditional techniques.¹⁹ Accordingly, digital scans of the preparations were taken using the digital scanner, and occlusal records of both arches were submitted to the laboratory (Figure 10). Provisional restorations in Luxatemp BL were fabricated using a stent from the wax-up model and reviewed for occlusion and aesthetics after 2 days, with no fractures noted.

Upon patient approval of the provisional restorations, a digital scan was taken to enable replication of shape and proportions in porcelain (Figure 11). The laboratory prescription included detailed instructions reflecting the patient's desired veneer style, and restorations were returned for review on stone models prior to cementation (Figure 12). The patient returned 3 weeks post-preparation with intact provisionals, indicating stable aesthetic and functional harmony. The provisionals were removed using an ultrasonic scaler and excavator, and restorations were trialled with neutral try-in paste. Satisfied with the shape, shade, and character, the patient approved the restorations, which exhibited excellent marginal adaptation, free from voids, and ideal occlusion. Fitting surfaces were treated with HF acid and silane prior to cementation (Figure 13).

For cementation, air abrasion with aluminium oxide was performed, and rubber dam isolation applied. Although evidence supporting rubber dam use in reducing failure rates is low, it is widely endorsed in clinical practice. A split-dam approach was employed to minimize recession risk in the buccal cervical regions.²⁰ The restorations were bonded with a resin-based luting cement, employing a three-step etch, prime, and bond protocol (Figure 14).

At 2 weeks post-cementation, a follow-up review confirmed gingival healing, with no complications reported (Figure 15). A Michigan splint was fabricated for night-time wear, and a daytime orthodontic retainer was provided to prevent relapse. The patient was monitored closely over 3 months, after which posterior sextant rehabilitation was planned. Evidence supports the superiority of ceramic materials for posterior restoration in complex rehabilitative cases.^21,22

At the 3-month review, no issues, such as porcelain fracture or debonding, were observed. The patient was asymptomatic and maintained excellent orthodontic retention and oral hygiene, demonstrating compliance with the post-treatment care protocol.

Posterior sextant porcelain rehabilitation

The patient expressed a strong interest in advancing to the final restorative phase for the posterior sextants. New study models were obtained and articulated with a customised incisal guide plane on a semi-adjustable articulator, allowing comprehensive assessment for posterior restorations, including a veneer for UR5, onlay for UR6, crown for UR7, veneer-lay for UL5, crown for UL6, and onlay for UL7.

During the subsequent appointment, deconstruction of the upper first and second molars commenced for posterior restorations. As depicted in Figure 16, gold crowns on UR7 and UL7 were removed, with retention of the underlying cores because they remained asymptomatic, demonstrated sound margins and presented no clinical need for replacement, thereby optimizing cost efficiency. Additionally, the pinretained amalgam restorations on UL6 and UL7 were removed, followed by immediate dentine sealing (IDS) and onlay preparations. A traditional veneer preparation was undertaken on UR5, while a veneer-lay/onlay preparation was performed on UL5.

Provisional restorations were fabricated and evaluated for both functional and aesthetic adequacy prior to finalization with the laboratory. Upon return from the laboratory, the definitive restorations were scrutinized before inviting the patient for cementation, which was conducted under rubber dam isolation with resin cement, following a protocol akin to that employed in the anterior sextant.

At the 3-month follow-up (Figure 17), the patient reported no symptoms, with no evidence of porcelain fracture or debonding. The patient maintained excellent orthodontic retention and oral hygiene practices, alternating between a splint and an Essix retainer. Both the clinician and the patient were highly satisfied with the ortho-restorative outcome. The success of this case can largely be attributed to the patient's understanding and compliance with each treatment phase, especially the preparatory orthodontic movement preceding the restorative interventions. Regular reviews of this case have reinforced the success and positive trajectory of the treatment outcomes to date.

Conclusion

Overall, the functional and aesthetic outcome was well received. The success of highly aesthetically motive-driven treatment like this was supported by having a well-informed patient, with well-adjusted expectations. This case report highlights the importance of planning and design in setting these expectations, but also demonstrates the advantage of phasing treatment. The use of pre-restorative orthodontic treatment can be clearly demonstrated in this case to optimize aesthetics and enable the delivery of minimally invasive porcelain veneer restorations.