Patients with severely worn teeth may benefit from full-mouth rehabilitation with an increased vertical dimension. This treatment demands a diagnosis based on the thorough examination of the vertical dimension, condition of the remaining teeth, and the history of temporomandibular joint dysfunction.1,2 To successfully increase the vertical dimension, preliminary casts are required to duplicate the patient's initial oral state and dental occlusion. A face-bow and check bite in centric relation position are traditionally employed to transfer the cast to the articulator. By increasing the articulator's incisal guide pin, a temporary dental prosthesis can be produced based on the newly determined vertical dimension.3 During the adaptation period, patients and clinicians exchange perspectives and apply them to final restorations with the newly determined vertical dimension. During the systematic evaluation and diagnosis of the patient’s condition, clinicians should reevaluate the functional and aesthetic adaptations after increasing the vertical dimension, including soft-tissue comfort, masticatory function, and phonation.
Patients with disabilities present a high prevalence of dental caries and periodontal disease caused by a lack of oral hygiene, often requiring full-mouth rehabilitation with increased vertical dimension. However, for most patients with disabilities, following the required procedure for full rehabilitation with increased vertical dimension can be challenging since these patients frequently lack comprehension or cooperation abilities when given specific instructions (i.e., opening or closing their mouth and mandibular lateral movements). Thus, in many situations, dental practitioners for patients requiring special care may diagnose and treat patients based on their own expertise and experience, rather than on a systematic evaluation.
Two main types of disabilities exist: physical and mental. Physical disabilities can be further categorized into brain disorders, or mobility, visual, hearing, and facial impairments involving bodily functions or internal organ disabilities. The scope of dental treatments available to patients depends on the type and severity of the disability. Therefore, treatment modifications to the prosthetic restoration plan for disabled patients are necessary. Among these, patients with hearing impairments generally do not face significant challenges with the dental treatment itself if they can cooperate with instructions from the clinician, but some considerations must be acknowledged.4,5 In this case report, we describe a case of full-mouth rehabilitation with vertical dimension increase in a patient with hearing and speech impairment.
Ⅱ. Case Report
A 47-year-old man with severe hearing and speech disorder visited the National Dental Care Center for persons requiring special care at the Seoul National University Dental Hospital, consulting for an aesthetic problem, decreased masticatory function, and pain. An intraoral examination revealed retained roots due to dental caries, as well as extensive attrition of mandibular anterior teeth in the absence of antagonists (Fig. 1). Additionally, the mouth opening was restricted, and the muscles around the mouth were hypertonic.
The patient’s constant jaw movement with an unstable occlusion, along with his inability to understand the doctor's instructions, prevented an appropriate diagnosis. As a result, we determined the amount of increased vertical dimension using only the Willis facial indications. Over the next three months, the patient’s guardian immobilized his head, analyzed his muscle tone, and monitored his eating habits with temporary restorations, including videotaping during meals. After three months of periodic occlusal bite checks, a decision was made to attempt rehabilitation with a 7 mm increase in the vertical dimension of the anterior teeth. Permanent porcelain-fused metal crowns were fabricated using a cross-mounting technique while preserving the increased vertical dimension of the temporary restorations. However, periodic occlusal checks were still required six month after treatment.
Extraction of retained roots and multiple endodontic treatments were performed prior to prosthodontic treatment to relieve discomfort and eliminate inflammatory tissue. All of the remaining teeth were prepared and set with temporary bridges for a four-month adaptation period. Four maxillary anterior dental implants were placed after considering the newly determined vertical dimension and positions of neighboring and opposed teeth.
The implant surgery was performed in two stages. In accordance with the final prosthetic plan, we decided to place implants into the sites of the right maxillary second premolar and molar, and left maxillary central incisor and molar. In cases where there was insufficient remaining bone, additional procedures were performed simultaneously to make the most of the available bone (Fig. 2). In the maxillary right area, because the remaining bone had a depth of 5 mm, a sinus graft with a lateral approach was performed, and Osstem TS III 3.5(ø) × 10.0 mm and Osstem TS III 4.5(ø) × 10 mm implants (Osstem implant Co., Ltd., Seoul, Korea) were installed in the #13 and #15 areas, respectively. Additionally, in the maxillary left area where the bone width was insufficient, Osstem TS III 3.5(ø) × 10 mm and Osstem TS III 4.0(ø) × 11.5 mm fixtures were placed with ridge splitting in the #21 and #23 areas, respectively. Therefore, instead of proceeding with healing abutment connections, the implants were submerged to promote osseointegration.
This patient exhibited a high muscular tone and thick gingival biotype. Consequently, caution was required when elevating the flap using a full-thickness flap technique. Additionally, since the vestibule was relatively shallow, vestibuloplasty was performed through an apically positioned flap during the second surgery to ensure the acquisition of sufficient keratinized mucosa, and to facilitate oral hygiene. During the second surgery, when the crestal incision was performed and the flap was raised, the incision was positioned lingually and accompanied by a vertical incision. The raised flap was positioned so that its buccal margin matched the margin of the healing abutment, thereby inducing secondary healing with a width equivalent to the diameter of the healing abutment between the flaps.
After three months of healing following the surgery, and while increasing the vertical dimension, the mandibular position was manipulated to a centric relation, resulting in a mandibular position that was backwards relative to the pre-treatment state. As a result, the overjet of the teeth increased considerably (Fig. 1). After a few months, the left mandibular posterior area will also be restored with dental implants for better masticatory function (Fig. 3).
This patient could be treated as an outpatient since he could tolerate pain, including anesthetic injections and surgery; however, some restrictions existed. First, he had an opening constraint and extra hypertonicity of the masseter and buccinator muscles. This condition made it difficult to take impressions of posterior lingualized teeth. Second, the lack of communication abilities and an uneven jaw posture in which the patient was continuously altering his mandibular position from side to side, made the achievement of a stable occlusion with a prosthesis very challenging.
Determination of vertical dimension is important for the fabrication of all restorations. Many approaches, including facial landmarks, swallowing, phonetics, rest space, and cephalometric radiography have been employed to quantify the vertical dimension of occlusion. For most people, physiologic occlusal vertical dimension is better described as a range rather than a set point or position, and the width of that comfort zone may vary depending on the patient’s adaptive capacity.6 In the present case, the key factors influencing vertical dimension establishment were the patient's facial landmarks as determined by the Willis method, and the observable soft tissue tension around the mouth.7
Increased masticatory muscle tone can increase masticatory dysfunction. The increased muscular tone around the mouth of this patient raised our concern about his ability to adapt to an increased vertical dimension; therefore, we planned a full-mouth rehabilitation with minimum vertical dimension elevation to create space for restoration. The maximum intercuspation of the teeth had to be established to achieve a stable occlusion and better masticatory function. Nevertheless, a non-harmonized jaw size and arch form, and non-constant mandibular position resulted in final restorations with dual bite side to side. Additionally, we encountered difficulty in creating an accurate prosthesis due to the stiffness/hyperactivity of the patient’s tongue and cheeks. After rehabilitation, his jaw did not move in the anterior or posterior orientations, as compared to the movement we observed before treatment. Following treatment, the patient's functional and aesthetic issues were resolved, and his guardians were pleased with the results, including an improved ability for eating and maintaining a stable occlusion over the follow-up period.
Temporomandibular joint (TMJ) disorders can cause reduced mandibular range of motion, dental mal-occlusion, pain, joint sounds, fascia pain, among other functional difficulties, and affect approximately 40–60% of the population.8,9 Fortunately, the patient in this study did not appear to be in pain, but an evaluation of mandibular movement indicated that an opening restriction existed. This condition was evident since only rotational, and not translational movement of the condyle was observed, resulting in a maximum opening of 2.0–2.5 cm between the incisors after rehabilitation. Dysfunctional habits and TMJ disorders may be exacerbated by masticatory muscle activation following treatment, and difficulty performing fine occlusal-bite checks during rehabilitation. Therefore, the patient’s guardian was educated in self-exercise strategies and lifestyle-habit modifications to avoid and treat probable TMJ issues in the future. However, this approach may be ineffective if the patient does not understand the instructions. Nevertheless, regular check-ups and validation of healthy eating habits were strongly recommended.
Patients with disability receiving treatment at our center are mostly people with severe conditions with no precise diagnosis. Typically, these patients were previously unable to undergo examinations due to financial constraints and a lack of cooperation. Although the morphology and intellectual ability of patients with hearing disability in this report was significantly different from those of other patients with the same condition, his inability to communicate clearly about his pain was similar. Therefore, in similar cases, clinicians or guardians must closely observe to determine what, exactly, the patient’s problem is.
Implant surgery in patients with disabilities, especially in cases like this one, is typically conducted in two stages. This approach is taken because, even if an initial stability is achieved, occasional instances of failure have occurred when a healing abutment is attached, positioning it toward the gingiva. Many patients with disabilities have difficulty adhering to precautionary measures and maintaining oral hygiene. They may inadvertently apply non-functional force to the fixture, such as pushing with the tongue or attempting to remove the fixture with their hands. Therefore, in implant procedures for patients with disabilities, simultaneous implantations in the first and second surgeries are carried out only in cases where initial stability is achieved, precautions are diligently followed, and oral hygiene management is excellent. In other cases, a two-stage approach is recommended.
Patients with hearing disability often use hearing aids as assistive devices. However, in cases where cochlear function is severely impaired and hearing aids are not effective, cochlear implant surgery is performed. According to research, during tooth preparation, the high-speed handpiece generates noise at 85 dB, the low-speed handpiece at 78 dB, and the scaler at 85 dB. Even the sound of saliva suction reaches 77 dB.10 During dental procedures, the sounds generated by equipment such as high- and low-speed handpieces can be amplified and cause severe discomfort to these patients. Therefore, we recommend removing hearing aids, including cochlear implants, before all dental procedures. As a result, patients will more easily be able to follow doctor’s instructions in dental clinics.
The center currently provides dental treatment for people with disabilities and attempts to make dental care more accessible by providing suitable facilities, support from workers with specific areas of expertise, and the use of restraints such as pedi-wrap for adults. Despite these efforts, dental treatment for patients with severe disabilities is challenging. It is crucial to continue researching and developing specific treatment for patients with disabilities as our expertise grows. Furthermore, we anticipate that in the future, with the advent of artificial intelligence and robotics, dental procedures will become more efficient.
Most patients with disabilities experience difficulty restoring their teeth, especially during full-mouth rehabilitation. In many situations, because of lack of comprehension or cooperation, dental practitioners for patients requiring special care can only diagnose and treat patients based on their own expertise and experience and not on a systematic evaluation. However, after a period of adaptation and full-mouth rehabilitation, patients with disabilities are typically pleased with their new appearance and masticatory function, resulting in a better nutrition and weight gain.