
==== Front
Ann Med Surg (Lond)
Ann Med Surg (Lond)
MS9
Annals of Medicine and Surgery
2049-0801
Lippincott Williams & Wilkins Hagerstown, MD

10.1097/MS9.0000000000000094
00003
3
Original Research
Guide devices in the rehabilitation of interrupting mandibular bone defects: a proposal for a new classification
http://orcid.org/0000-0002-0296-444X
El Hawari Wijdane MD wijdane.elhawari@um5.ac.ma

http://orcid.org/0000-0002-9202-5402
Habib I Abdoul Majid MD abdoulmajidhabib@gmail.com

http://orcid.org/0000-0002-1887-0368
Bentahar Oussama MD drbentahar@gmail.com

Department of Prosthodontics, Faculty of Dental Medicine, Mohammed V University in Rabat, Morocco
* Corresponding author. Address: Department of Prosthodontics, Faculty of Dental Medicine, University MOHAMMED V, Rabat. Avenue Allal Al Fassi, Rue Mohammed Jazoulit, Madinat Al Irfane, BP: 6212, 10000 Rabat. Tel.: +212637642136. E-mail address: wijdane.elhawari@um5.ac.ma (W. El Hawari).
3 2023
9 3 2023
85 3 378382
9 11 2022
13 12 2022
Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.
2023
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0/

Interrupting mandibular surgical resections may lead to mandibular deviation toward the resected side. This further complicates future surgical and prosthodontics reconstructions. The rehabilitation of this mandibular deviation by the specialist in maxillofacial prosthodontics is often done by guide devices. This helps to prevent or reduce postsurgical mandibular deviation. The current literature lacks data on a standard classification of these devices despite the various clinical situations that require different rehabilitation techniques. After a deep appraisal of the current literature on this topic and many years of experience, the authors propose an overview of the indications, the types, and an original classification of these prosthetic devices. We believe this new classification will facilitate communication among practitioners, the development of treatment plans, and the comparison of outcomes among different expert centers.

Keywords:

guide devices
mandibular deviation
mandibulectomy
prosthetic rehabilitation
OPEN-ACCESSTRUE
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pmcIntroduction

The mandibular surgical resection is indicated for the treatment of neoplastic lesions, trauma, or infections. It can lead to interrupting or noninterrupting bone defects1, and causes severe and disabling facial deformities, which create functional, aesthetical, and psychological issues for patients2–4. As for interrupting mandibular surgical resections, a mandibular deviation is the most common complication in the absence of surgical reconstruction. This sequela is managed by specialists in maxillofacial prosthodontics. Indeed, they design guide devices to rehabilitate the mandibular deviation before any surgical reconstruction and also ensure prosthetic rehabilitation after surgical interventions. Of note, a collaboration between multidisciplinary teams composed of a maxillofacial surgeon, an oncologist, a psychologist, and a maxillofacial prosthodontist is required and crucial for optimal management. Currently, a classification of guide devices was not developed yet and is urgently needed. Our new classification is supposed to facilitate communication among practitioners, the development of treatment plans, and also the comparison of outcomes between different centers. In fact, the old classification of Neicher, founded in 1993, is not relevant in our context, given the presence of loss of mandibular substance5. Indeed, it describes the artificial relationships between the two dental arches from plaster models manipulated in a situation of maximum intercuspation.

The Brown classification was used as it is the most recent, and it is currently practiced by surgeons and oncologists for the diagnosis and management of cases of mandibular substance loss as compared to the HCL classification [hemimandibular (H), central (C), and lateral (L)]6. Accordingly, our present new classification combines these two previous models and enables accurate classification of cases with loss of mandibular substance based on Brown’s classification as well as the rehabilitation by guide apparatus. This may enable restoration of the mandibular deviation and, therefore, allow an optimal combination of different occlusal situations described by the Neicher classification. This perspective article aims to discuss prosthetic devices by specifying their types and indications. We also suggest an original classification to review the different types and technical designs of these devices.

Management of mandibular deviation: mandibular guidance therapy

Following tumor resection, the mandibular cinematics is altered. These changes include propulsion movements, deviation of the mandible toward the resected side, and the impossibility of the deduction movement on the healthy side. The goal of mandibular guidance therapy is to direct the mandible to a correct position in the sagittal and transversal route and to prevent the occurrence of retracted scar tissue bands7. This therapy is first initiated with postsurgical physiotherapy, which helps recover the buccal opening and closing as well as the laterality and propulsion movements of the mandible. These exercises are followed by guidance therapy.

To date, the most commonly used mandibular guidance encompasses maxillomandibular fixation, followed by prosthetic guidance and occlusal equilibration8,9. Regarding physiotherapy, it is the functional component of the management of mandibular substance loss. It includes manual massages that increase muscle trophicity and ligament stretching (passive mobilization) and active mobilization by muscular contractions10. The clinical objective is to obtain an acceptable opening movement, a mandibular recentering, and the recovery of the propulsive movement. The prerequisites for these exercises consist of warming up by thermotherapy, vibrotherapy, or massages of the cervical–facial muscles, followed by exercises to recover mouth opening, propulsion, and correction of the deviation. The recovery of laterality movements aims essentially to improve muscle strength, as it is recommended that the patient steers the mandible three times a day in all directions, first using his hands and then acting without any help. The recovery of the propulsive movements is performed by movements with counter resistance by the prosthodontist or by the patient by pulling the mandible forward and avoiding the deviation to the resected side10.

The rehabilitation sequence of the neuromuscular system, as recommended by Beumer, consists of exercises introduced early. It includes a maximum opening and pulling the residual mandible away from the surgical site. Notably, demonstrations should be performed periodically for the patient8. Different devices were described for active or passive mobilization with continuous or discontinuous action, with springs or elastic material. An illustrative example of passive mobilization devices is the TheraBite system, the Benoist grasshopper, and the Head balance system for active devices. To perform muscle reeducation, different types of utensils can be used including rubber stoppers, clothespins, and tongue depressors. The tongue depressor stacks are the most commonly used11. For maxilla-mandibular fixation, it is a technique used for cases with minimal resection of soft tissue. It is maintained 5–7 weeks after surgery to support proprioceptive sensation and the inter-arch connection during the initial postsurgical period8.

The place of guide devices in mandibular guidance therapy

There are several factors associated with imprecise mandibular movements, such as the loss of proprioceptive sensation, muscle imbalance, particularly the internal pterygoid muscle, and the contraction of scar tissues in the resected site11. These movements result clinically in a mandibular deviation which can be described as a rotation toward the unresected side (frontal plane of rotation)7. In this case, several anatomical structures are altered, mainly the pterygoid muscle, the elevator muscles, and the temporomandibular ligament12. Prosthetic treatment of patients suffering from these structural abnormalities has two major objectives, including an optimal rehabilitation of esthetics and function by re-educating muscles of the mandible and restoration of an acceptable occlusion13. The prognosis of rehabilitation depends on the site and the extent of surgery. In addition, other important factors such as the presence or the absence of the condyle on the resected side, the treatment plan established by the surgeon, the patient’s cooperation as well as the psychological aspect are also associated with outcomes7,14. The guide apparatus also constitutes an important preventive dispositive to restore mandibular guidance. It can be described as an artifice allowing the maintenance of the residual mandible with little or no lateral movement by guiding it toward a position of an acceptable occlusion15. Of note, the outcomes of this therapeutic strategy are more favorable in the case of tumor resections involving bone tissues only16. There are different types of guide devices, which can be categorized according to the clinical setting and also the technique of fabrication.

The restoration by the guide apparatus is indicated before surgical reconstruction, in case of failure, or during a contraindication of reconstruction surgeries. This procedure is optimal when the patient can achieve a correct mandibular position with the aid the clinician but without the ability of its reproducibility17. In other cases, the guiding device can be indicated to release the scar tissues and improve the mandibular position. The occlusal adjustment is an essential phase after the mandibular guidance therapy to re-enforce the mandibular position. It consists of the equilibration of occlusion following the modifications of the contours of the teeth. The patient must, then, learn to masticate properly after stabilizing the occlusion8.

Types of guide devices

The rehabilitation of partially edentulous patients with guide devices presents less difficulty as compared to complete edentulous patients because they tend to have a more pronounced mandibular deviation8. The presence of teeth on the two arches is important for effective guidance to support mandible reprogramming14. The guiding ramp can be made of acrylic resin or an alloy of cobalt chrome. The metallic apparatus allows small rectifications. Therefore, they are reserved exclusively for cases requiring minimal adjustments. It is attached to either a prosthesis (for totally or partially edentulous patients) or an acrylic resin splint with claps (for dentulous patients). In case of a severe mandibular deviation, the device with a palatal guide plane is preferred over the mandibular device18.

Three types of guiding apparatus can be described according to their anatomic setting:A mandibular prosthesis or a mandibular resin bivalve splint with a vestibular guiding ramp.

A maxillary prosthesis or a maxillary resin splint with a palatal guiding ramp.

A mandibular bivalve splint with two lateral vestibular guiding ramps for anterior interrupting mandibular resections: this design prevents the rapprochement of the residual fragments19.

According to clinical cases, many design protocols of guide devices have been described by different authors. We propose through the following new classification six categories using the six first Latin alphabet letters, from A to F. For schematic illustrations, the F letter designates all forces developed by the musculature and the scar flanges on one side as well as the forces counteracted in terms of resistance and guidance by the guide devices on the other hand. Thus, we have selected F1–F1′–F2–F3 as follows:

F1: Forces developed by the musculature and the scar flanges on the contralateral side of the substance loss.

F2: Forces counteracted by the guiding device.

F3: Forces counteracted by a second guiding device.

F1: Second contralateral developed force by the musculature and the scar flanges.

Class A: Figure 1

This guiding device is composed of two parts, a palatal plate made of acrylic resin or metallic alloy with claps to ensure its stability. The second part (the palatal guiding ramp) is made on the dental chair. A self-curing acrylic resin is used and the clinician places the resin on the palate and guides the deviated mandibular fragment to a correct or acceptable occlusal relation. The clinician is insure that the mandibular molars mark their path on the acrylic resin, thus forming the palate guiding ramp.

Figure 1 Class A – Schematic representation of maxillary guide device with palatal ramp.

Indications: class I, II, Ic, IIc, and IVc (Brown 2016 classification6).

Advantage: It has a strong guiding effect and the palate plate is stable.

Disadvantages: It may disturb the lingual function during phonation and deglutition.

Class B: Figure 2

This guiding device is composed of a maxillary prosthesis and it is used in case of tooth absence on the maxillary on the opposing side of the mandibular resection and when the complete reduction of the mandibular deviation is not possible. The lab technician makes a double prosthetic corridor, one for occlusal function, and the other for esthetics and cheek protection during mastication.

Figure 2 Class B – Schematic representation of maxillary guide device with double prosthetic corridor.

Indications: class I, II, Ic, IIc, and IVc (Brown 2016 classification6), generally in the context of mandibular resections left with no mandibular reconstruction.

Advantage: It provides a good compromise between esthetics and function.

Disadvantages: It may disturb the lingual function during phonation and deglutition.

Class C: Figure 3

This guiding device is composed of a mandibular bivalve resin splint with a buccal guiding ramp. The mandibular bivalve fitted splint is stabilized with metallic retainers that cross the occlusal plan.

Figure 3 Class C – Schematic representation of mandibular guide device with a buccal guiding ramp.

Indications: class I, II, Ic, IIc, and IVc (Brown 2016 classification6).

Advantage: It respects the lingual function.

Disadvantages: The bivalve splint is less stable as compared to the maxillary splint, which reduces the strength of the guidance.

Class D: Figure 4

When the loss of substance concerns the region of the mandibular angle or the ascending branch, the mandibular arch is placed in a retro position. This displacement is naturally much more marked on the side of the lesion. The guide is placed on this side. It must have two vestibular sliding planes. One superior is solidary of a palatal plate and has a sliding surface oriented backward and downward, and another guide is attached to the lower arch and has a plane oriented upward and forward. When they come into contact at the moment of occlusion, the two planes, by sliding one over the other, propel the mandibular arch forward and restore the correct occlusion.

Figure 4 Class D – Schematic representation of maxillary and mandibular guide device with sliding surface.

Indications: class III and IV (Brown 2016 classification6)

Advantage: This guide restores the occlusion and prevents the mandibular anterior–posterior deviation during the opening of the mouth.

Disadvantages: The laboratory construction of the palatal plate and the mandibular bivalve splint with their vestibular guiding ramp is time-consuming and requires a skilled lab technician.

Class E: E1 and E2, Figures 5, 6

It consists of the combination of the techniques mentioned above aiming to strengthen the guidance and this encompasses two types:

Figure 5 Class E1 – Schematic representation of association of class A with class C guiding device.

Figure 6 Class E2 – Schematic representation of association of class B with class C guiding device.

Type E1

A maxillary guide device (resin splint or denture) fitted with a palatal guiding ramp combined with a mandibular guide device (bivalve splint) fitted with a buccal guide flap (A+C).

Advantage: Stronger guidance.

Disadvantages: The same as classes A and C.

Type E2

It is a combination of a partial or complete maxillary guide prosthesis with a doubled prosthetic corridor and a mandibular prosthesis fitted with a vestibular guiding ramp (B+C).

Advantage: stronger guidance.

Disadvantages: The same as classes B and C.

Class F: Figure 7

When the loss of substance is median and involves the symphysis region, the two bony fragments tend to approach each other as well as a formation of scar tissues. This phenomenon complicates future surgical reconstruction. To prevent this adverse effect, two mandibular guide devices with buccal guiding ramps are used, the latter is joined by a metallic lingual bar crossing the loss of substance thus preventing the two segments from coming together.

Figure 7 Class F – Schematic representation of association of class B with class C guiding device.

Indications: class I, II, Ic, IIc, and IVc (Brown 2016 classification6).

Advantage: It prevents the unesthetic deformation of the mandibular bone.

Disadvantages: Its stability is conditioned by the number and periodontal quality of the remaining mandibular teeth.

Conclusion

The role of guide devices in restoring a fairly correct mandibular position is evidenced. Mandibular guidance therapy is one of the objectives to be achieved by the maxillofacial prosthodontist. On the one hand, it facilitates the reconstruction surgery or overcoming its failures and on the other hand, it also facilitates the subsequent prosthetic rehabilitation. The present work of guide devices may support the current literature that lacks an actionable classification. The communication among the medical centers and different practitioners involved in the management of patients with mandibular interrupting bone defects will therefore be facilitated.

Ethical approval

Not required for this article type.

Patient consent

Not applicable.

Sources of funding

None.

Author contribution

All authors: study concept; W.E.H.: writing the paper.

Conflicts of interest disclosure

The authors declare no conflicts of interest.

Research registration unique identifying number (UIN)

None.

Guarantor

Wijdane El Hawari.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability

Not applicable.

Acknowledgments

All the authors contributed to the conduct of this work. All authors also declare that they have read and approved the final version of the manuscript.

Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

Published online 9 March 2023
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