The evaluation of maximum bite force in the occlusal rehabilitation of patient with Angle Class III malocclusion: a case report
A male patient aged 33 years old was self-referred to the Faculty of Dentistry at University of Gazi. The main complaints of patient were difficulty in masticatory function and poor esthetic. The patient's medical history was reviewed and it was decided to be non-contributory. An extensive clinical examination was also made. On extraoral clinical examination, retruded upper lip with prominent lower lip was noted as usually seen in Class III malocclusion (). Cephalometric analysis of patient revealed that patient had Angle Class III malocclusion (ANB = -5). In dental examination, it was detected that Class III cuspidfirst molar relationship and anterior crossbite with the negative horizontal overjet in centric relation, diastemas in anterior teeth, and missed three molar teeth number of 17, 26 and 47 (). There was no caries, wear or restoration on teeth. The periodontal examination showed the presence of plaque and generalized staining. In the evaluation of temporomandibular joint, no history of dysfunction was reported and, no joint sound and pathology was revealed. Masticatory muscles, head and neck muscles were normal to palpation. The mandibular range of the motion and jaw opening were within the normal limits.\nBefore the treatment, maximum bite forces were measured from each side of the dental arch using two miniature strain-gauge transducers with stainless-steel cases (Model VLPB, Load Cell Central, Monroeton, PA, USA). Each transducer had a height of 4 mm and a diameter of 12 mm. The bite force was detected as a two-channel signal from each side with a biosignal acquisition device designed by Kardiosis (Tepa, Kardiosis, Ankara, Turkey). The force signals were monitored online and then measured on a PC screen, using a specific software program developed by the same company. Two transducers were placed bilaterally in contact with maxillary first molar teeth over metal plate. The transducers fixed with plaster (Betasan, Kocaeli, Turkey) to the metal plate. Then, metal plate and transducers were covered with a disposable latex finger coating to avoid contamination. During measurement, the subject was asked to clench teeth as forcefully as possible three times. The highest value of each clenching was recorded as kilogram (kg), and the mean value of the three highest clenching was considered as the subject's maximum bite force. The sum of the right and left bite force values was considered to be the maximum bite force of the subject. Maximum bite force of patient was measured as 42 kg before treatment.\nTwo following treatment options were discussed with the patient; (1) Orthodontic treatment and following surgical treatment, (2) Restorative treatment with increasing of OVD. The patient was informed about all the advantages, disadvantages and possible risks of both treatment options. In that patient, even if the orthodontic treatment is accomplished, the shape, size and color of present teeth would remain the same. Also orthodontic and surgical treatment would also require extended treatment time. On the other hand, as another option, restorative treatment would involve the preparations of all maxillary and mandibular teeth for improving occlusal relationships and also increasing of OVD. The patient's expectations from the treatment were a good esthetic and masticatory function with a less invasive way in a relatively short time. Therefore, increasing of OVD and then restoring the maxillary and mandibular teeth was decided to be chosen as the treatment option of patient. Full mouth rehabilitation with metal ceramic restorations was suggested to patient.\nAt first, periondontal treatment was performed and oral hygiene instructions were given. Then, irreversible hydrocolloid impressions (Hydrocolor 5, Zhermack, Zhermack SpA., Badia Polesine, Italy) of maxillary and mandibular teeth were made to obtain diagnostic casts. A face bow record (UTS Face-bow, Ivoclar Vivadent, Austria) and an interocclusal record in centric relation were completed and diagnostic casts were mounted in a semi-adjustable articulator (Stratos 300, Ivoclar-Vivadent, Austria). The new OVD was established using Niswonger method and facial measurements. Patient had increased interocclusal rest space (7 mm in the anterior teeth), therefore 3 mm rest space was pretended and actual increase were determined as 4 mm in the anterior teeth and 2 mm in the posterior teeth and the incisal guidance pin of the articulator was set.\nDiagnostic casts were evaluated and wax up of all anterior teeth with final contour and position was accomplished at the new OVD. Then an auto-polymerized acrylic resin (Panacryl, Arma Dental, İstanbul, Turkey) occlusal splint was provided to evaluate the adaptation of the patient to altered OVD. The splint was adjusted intraorally to ensure bilateral anterior and posterior simultaneous contacts in centric relation. Anterior region of splint prevented occlusion of splint, therefore excess of acrylic resin was removed from anterior region of splint (). Patient was instructed to wear splint during 24 hours, for 4 weeks. In clinical examination after the first week, no muscle tenderness and temporomandibular discomfort was found.\nAfter the verification of functional adaptation to new OVD, anterior teeth were prepared for definitive treatment. In this session occlusal splint was used to check the preparation amount of anterior teeth and to take bite registration by placing the splint into mouth. Posterior teeth were occluded and anterior part of splint was supported with wax. Then posterior teeth were prepared. At this time anterior part of occlusal splint was occluded and posterior part was supported with wax. After preparation of all anterior and posterior teeth (), final impressions were made with polyvinylsiloxane impression material (Optosil Comfort/Xantopren VL Plus, Heraeus Kulzer, Hanau, Germany) and provisional restorations were fabricated using an auto-polymerized acrylic resin. The provisional restorations were used for one month, as a guide for the definitive restoration. During this period, the patient's condition and functions, such as muscle tenderness, temporomandibular joint discomfort, range of the mandibular movements, masticatory function, swallowing and speech were evaluated. Improvement in masticatory function, speech, and dentofacial esthetics affirmed the patient's tolerance to the new OVD. In the following session, metal substructures (Kera N, Germany) of restoration were adjusted. After the adaptation of metal substructure, the trial of ceramic restoration (Ceramco 3, Dentsply, Dreieich, Germany) were accomplished with minor occlusal adjustments. The occlusal sheme of definitive restoration was designed as mutually protected occlusion. During excursive mandibular movements the anterior teeth protected the posterior teeth from excursive force and posterior teeth supported the bite force in the maximum intercuspal position. Then definitive restorations were glazed and cemented with zinc polycarboxylate cement (Adhesor-Carbofine, Spofa-Dental, Germany) (). Oral hygiene instruction and regular check-up were administered.\nOne week later cementation of definitive restoration, maximum bite force was remeasured and recorded as 106 kg (). Patient reported increased masticatory efficiency with treatment.