Combined Orthodontic, Orthognathic Surgical, and Prosthodontic Treatment for Severe Class III Malocclusion Using Digital Workflows Open Access

With the development of digital technology, new methods are emerging in every dentistry field, making the everyday tasks of a practicing dentist significantly easier.¹  The availability of software enabling the digital planning of combined orthognathic surgery and orthodontic treatments has brought a significant change for orthodontists, maxillofacial surgeons, and patients.²  Virtual surgical planning is now part of everyday practice; with its help, the esthetic and functional results of surgical treatments have become more predictable, and the process of surgical planning has been significantly shortened. In our case presentation, we describe a skeletal Class III patient we treated.

The comprehensive treatment of skeletal Class III malocclusion is a serious challenge and often requires interdisciplinary thinking. The etiology of this malocclusion is sprawling; Class III anomalies are polygenic, so genetic factors and environmental influence are also present in its development.³  The clinical manifestation of a severe skeletal Class III malocclusion consists of mandibular overgrowth, maxillary underdevelopment, or a combination of these. Therapeutically, dental and dentoalveolar compensation with mandibular distalization is often performed. Clinicians often use TADs (temporary anchorage devices) to distalize the entire mandibular arch or extract premolars or even molars to gain space for lower anterior teeth retraction.⁴  Although these treatment possibilities have become popular, clinicians must keep in mind that these results are compensatory. In severe cases, to achieve proper functional and esthetic results, a combined orthodontic and orthognathic surgical treatment is needed. Nowadays, surgical treatment planning and implementation are fully digital, making the whole process much more predictable for orthodontists and maxillofacial surgeons so that they might indicate these treatments with more confidence.⁵ 

The first advantage of digital surgical planning is the possibility of intraoral scanning, which replaces the need for silicone impressions. Previously, the analog impression was challenging because the brackets, tubes and other auxiliaries created varied surfaces, making it difficult to remove the impression. Sometimes brackets debonded during this process and made the last steps of the presurgical phase stressful for the patients and doctors as well.⁶ 

In digital surgical planning software (IPS CaseDesigner, KLS Martin Group, Tuttlingen, Germany), 3D facial scans can be integrated. The software's artificial intelligence (AI) can predict the final patient profile by simulating the facial changes resulting from the bony movements.²  For ideal and consistent restorative outcomes, digitally planned prosthodontic treatments often follow relatively similar steps.⁷  The development of new, or implication of existing treatment guidelines may help the prosthodontists achieve even more predictable results.⁸ 

Lithium disilicate and feldspathic ceramics are the most used indirect materials for esthetic restorations. The advantages of feldspathic ceramics in esthetics, color stability, translucency, and biocompatibility are widely established. The fracture resistance of lithium disilicate ceramics is higher than that of feldspathic ceramics, increasing their clinical lifetime in addition to their esthetic and practical qualities. Both have a broad variety of shades, the capacity to mimic translucency, fluorescence, and the ability to guarantee color stability.⁹ 

Preparations for minimally invasive treatment alternatives in dentistry are now easily achievable with the combination of the adhesive approach and translucent restorative materials. Lithium disilicate ceramic and other materials with characteristics like those of natural teeth have produced excellent results.⁸ 

Using computerized planning technologies and digitally created wax-ups for diagnostic purposes based on intra- and extraoral structures is achievable. The digitally constructed diagnostic wax-up may be 3D-printed and transferred to the mouth before tooth preparation to evaluate the function, esthetics, and phonetics. This technique establishes the incisal edge's precise position, character, and dimensions.

For dentogingival changes, digital smile design is an effective diagnostic technique.¹⁰  Digital planning offers straightforward procedures to assess gingival contour, tooth size, shape, and location using few but accurate photos and pre-preparation scans.¹¹ 

This case demonstrates a minimally invasive approach to preparation, CAD-CAM monolithic lithium disilicate ceramic veneers, and a fully digital design process to produce an esthetic smile.^12–13 

The chief complaint of the 18-year-old female patient who visited the Semmelweis University Department of Paedodontics and Orthodontics was her profile. During the diagnostic processes a dentally slightly compensated skeletal Class III malocclusion was diagnosed. Intraorally, on the right side, ¼ premolar width Class III canine and molar relations were registered, while on the left side, Class I canine and ¼ premolar width Class III molar relations were diagnosed. Vertically, the patient presented a mild open bite, and she also had a transversal maxillary deficit, which is a common disorder in skeletal Class III patients (Figure 1).

The values measured during the cephalometric measurements were as follows: SNA: 76.2°; SNB: 80.4°; ANB: -4.2°; Wits appraisal: -13.4 mm. (A Wits appraisal is an anteroposterior linear measurement of the jaw relationships, using perpendiculars from points A and B to the occlusal plane¹⁴ ). In addition to the sagittal deviations, we also diagnosed a deviation in the vertical plane. Based on cephalometric values, the dental open bite was associated with skeletal hyperdivergence: ML-NSL: 42.6°; NL-NSL: 10.0°; ML-NL: 32.6°. The axial position of the upper incisors was labially inclined due to the alpha angle of 111.5°, while the axial position of the lower incisors was lingually retroclined (IMPA: 68.7°) (Figure 2).

Based on the diagnostic measurements, a combined orthodontic and orthognathic surgical treatment was planned with three phases.

Orthodontic decompensation was performed using an upper-lower fixed appliance with a 0.018” slot size RMO FLi-Twin bracket system (Rocky Mountain Orthodontics Europe, Illkirch-Graffenstaden, France). The purpose of this was to further increase the sagittal distance between the upper and lower dental arches, thus creating a significant negative overjet, which makes it possible for the maxillofacial surgeon to perform significant sagittal movements on both the maxilla and the mandible. Due to the protrusion of the upper incisors, maxillary retraction was needed. To perform this, it was necessary to remove two upper premolars (teeth 5 and 12). The resulting space was closed by pure retraction of the anterior teeth, which required skeletal anchorage. Skeletal anchorage was achieved with orthodontic mini-implants (Dual-Top TAD, Rocky Mountain Orthodontics Europe) placed interradicularly between teeth 3-4 and 13-14. The mini-implants were used as direct anchorage. Spaces were closed after alignment on a sectioned 0.016” x 0.022” stainless steel archwire, with the help of a powerchain (Tru-Chrome archwire & Energy Chain powerchain, Rocky Mountain Orthodontics Europe) inserted between power hooks (Figure 3) bent distally from teeth 6 and 11 and the mini-implants. In the mandibular arch, a simpler tooth alignment was made. From teeth 23-26, lingual root torque was bent to get even more negative overjet and proper lower incisor axis angulation (Figure 4).

In the next step, upper and lower analog impressions were made, and a facebow registration with a dual wax bite (Alminax Accurate Bite Registration Wax, Kemdent, Associated Dental Products Ltd., Swindon, England) was recorded to define the centric relation (CR) position of the temporomandibular joint (SAM 2P articulator and Axioquick facebow, SAM Präzisionstechnik, Munich, Germany). Based on this diagnostic information, a mandibular occlusal splint was fabricated (Figure 5). The patient wore the splint 24 hours a day for 2-3 months before surgery.¹⁵ 

The importance of occlusal splint therapy before orthognathic surgery is to position the condyle into the CR position. To record the cone-beam computed tomography (CBCT) required for surgical planning, another articulation was performed to create a wax bite in the CR position (using the same bite registration wax as previously). With the help of the wax bite, the condyles can be kept in the CR position during the entire CBCT recording (ProMax 3D Mid, Planmeca, Helsinki, Finland), maintaining the condyle in the most favorable position for surgical planning.^16–18 

Two weeks before the surgery, the final intraoral scans, CBCT record, and 3D facial scan (ProFace, Planmeca, Helsinki, Finland) were imported and superimposed in the surgical planning software (IPS CaseDesigner). In the software, the “wish occlusion” was defined, and LeFort 1 and bilateral sagittal split osteotomy (BSSO) incisions were executed. The created bone segments were moved into the desired positions. The maxillary segment was positioned in an ideal position based on surgical preferences, facial esthetics, and functional aspects (Table 1). The program moved the mandible to the optimal position based on the previously created “wish occlusion.”

Not only was the bony postsurgical result predicted, but the postsurgical soft tissue conditions were also visualized thanks to the facial simulation. The facial simulation worked as an effective tool for outcome prediction and helped communication with the patient during the surgical treatment planning (Figure 6).^19–20 

After achieving the desired results, two surgical splints were created in the software, printed using a 3D printer (AccuFab L4D printer, Shining3D, Hangzhou, China and KeySplint Hard resin, Keystone Industries, Gibbstown, NJ, USA), and post-processed following the manufacturer's instructions. The first splint was applied to the mandibular arch and determined the correct position of the maxilla. After the maxilla was fixed in the desired position with miniplates, the second surgical splint was placed, allowing the mandible to be adjusted to the planned position. Stainless steel wire ligatures were used to attach the second surgical splint to the Kobayashi ligatures on the brackets. The second surgical splint was kept in place for 4-6 days after surgery (Figure 7). The fit and accuracy of 3D-printed surgical splints are superior to the previously used, manually made ones. During the postoperative intermaxillary fixation elastic rubber bands were used.²¹ 

After the orthognathic surgery, the patient was ordered back for evaluation two and four weeks later. Intermaxillary elastics were used for a further six months to maximize the final intercuspidation, while monthly functional evaluation was carried out to identify any occuring occlusal interferences. During this period, both temporomandibular joints were asymptomatic, and no functional shifts or early contacts were observed. Due to the patient's Bolton discrepancy, spaces between teeth 6-7 and 10-11 were not closed but redistributed to achieve the best outcomes with indirect restorations. The digital model analysis (OnyxCeph³, v.3.2.211, Image Instruments, Chemnitz, Germany) provided exact data regarding tooth widths and arch lengths, allowing precise planning of spaces during the orthodontic finishing, following the preliminary prosthodontic treatment plan. The equal distribution of available spaces, with a diastema between the upper central incisors (tooth number 8-9), was undesirable. The mesial contact of these teeth was kept intact to achieve a sufficient tooth length and width ratio and to avoid the preparation of mesio-approximal surfaces. The veneers were designed accordingly during the smile design to allow better proportions of the central and lateral incisors. After the orthodontic finishing, vacuum-formed retainers were produced to retain the achieved results.

Our treatment plan was four IPS e.max CAD MT (Ivoclar, Schaan, Liechtenstein) lithium-disilicate ceramic veneers (teeth numbers 7, 8, 9, 10) for closing the diastemas between the front teeth. The patient requested to change the shape of the upper front teeth from cubical to more rounded. The initial situation was scanned with a TRIOS 3 Wireless Pod (3Shape, Copenhagen, Denmark). The next step was the 2D smile design, based on the clinical pictures from the actual situation (Figure 8.).

The next step was the 2D smile design, based on the clinical pictures from the post-orthodontic situation (Figure 8.). This visualization was planned with TRIOS Smile Design (3Shape). The 3D design (Figure 9) was made with 3Shape RealView Engine (3Shape). The digital wax-up was printed using the NextDent 5100 (NextDent, Soesterberg, Netherlands) with Model 2.0 resin (Software: 3D Sprint For Ceramill, v.3.1.0.1257, 3D Systems Co., Valencia, United States). A silicone impression (Elite HD+, Zhermack, Badia Polesine, Italy) was used to register the new situation. This impression facilitated the transfer of the new design to the mouth, without preparation, by using self-curing resin (Structur 2 SC, VOCO, Cuxhaven, Germany) as a diagnostic mock-up. After 24 hours, the patient returned to the dental office to give her feedback regarding the mock-up, highlighting that it does not fully illustrate the final restoration due to the lack of preparation and its material. As profile esthetics can be influenced by the changes of lip protrusion, overjet and overbite, the soft tissue changes were evaluated as well. Minor corrections were made, and the revisions were scanned back as a pre-preparation scan. Minimal invasive preparation was made through the mock-up with orientation grooves, and the precision situational impression was taken digitally with Trios 3 (3Shape) (Figures 10 and 11). While the accuracy of scanners differs, the scanning technique may also influence the results. Scanning of the palate was utilized, as recent evidence suggests it increases the accuracy of the impression during maxillary digital impressions.²² 

Based on the scan, the veneers were planned with TRIOS Design Studio (3Shape). After production of the restorations (Figure 12), delivery was made in absolute isolation, cemented with Maxcem Elite Clear (Kerr, Brea, CA, USA). The last step was making a new vacuum-formed retainer for the upper arch. After the clinical phase, we evaluated the results with photos (Figure 13) and superimposed the pre- and posttreatment cephalograms. (Figure 14)

The final restorations and the lower retainers at the six-month follow-up visit can be observed in Figure 15.

The entirely digital approach of planning orthognathic surgeries and producing dental veneers has various advantages over analog methods. Precision is one of the key benefits. Digitizing the surgical workflow makes the whole surgical process more predictable. Post-surgical face visualization helps the team achieve the best possible functional and esthetic results, which previously was difficult to reach with analog methods.^2,23  While the involvement of the surgeon, orthodontist, and prosthodontist differs between the levels of macro, mini and micro esthetics, a collaboration during the entire treatment planning process enables the team to create a comprehensive treatment taking all aspects into consideration, from facial heights to gingival margins. Even in cases where collaboration between specialists is not essential, using diagnostic tools and ideologies of other fields may help the development of a more detailed treatment plan.

In this case, the orthodontic movements affecting profile esthetics and surgical movements were discussed between the orthodontist and maxillofacial surgeon prior to the beginning of the treatment, allowing the prediction of soft tissue changes; desired incisor inclinations, incisor exposition, transversal dimensions, possible early contacts and the expected autorotation of the mandible were all taken into consideration. The expected outcomes were discussed with the patient.

With 3D planning and printing the surgical splints, surgeons can achieve better surgical splint fit than before, which improves the treatment's result and reduces the risk of unwanted jaw movements, so a higher level of care can be achieved.²⁴ 

Another benefit of digital surgical treatment planning and veneer design is the increased patient involvement and customization. After treatment planning, the surgical team can predict the final hard and soft tissue result, which can be presented to the patient. This improves communication and patient experience and helps to avoid future problems resulting from improper information. Before the veneers are produced, patients may see the results and make revisions or alterations to ensure the final product matches their specific requirements and wishes.

Moreover, a digital workflow enables more efficient and simplified manufacturing with high-precision intraoral scanning. Digital surgical planning requires an intraoral scan instead of analog silicone impressions, reducing the risk of bracket debonding during the procedure, which can be frustrating in the last phases of surgical planning. Making impressions from the teeth, producing a model, and physically sculpting the veneer from porcelain or other materials are all steps in traditional veneer fabrication. This is a time-consuming process that may require several visits to the dentist. In contrast, a digital veneer design may be accomplished in a single visit. The computer design is delivered to a milling machine, which rapidly produces the veneer from high-quality materials like ceramics or zirconia.

Overall, the completely digital method of producing dental veneers has significant advantages in accuracy, efficiency and personalization, making it an attractive choice for both patients and practitioners.

The 3D surgical planning procedure can be a favorable alternative to analog solutions. After overcoming the initial difficulties (3D workflow, getting to know the software, perfecting their use), 3D surgical planning became integral to orthodontists’ everyday lives at Semmelweis University. The time required for surgical planning was significantly reduced, while the postoperative results became more predictable. Combining these treatments with modern, digital prosthodontic care improves complex cases’ outcomes.