Bite Fork Research Articles

Digital workflow in oral splint manufacturing.

The objective of the present article is to demonstrate the digital workflow used to manufacture an adjusted oral splint in a patient case. A 25-year-old female patient presented for management of her bruxism. Therefore, an adjusted oral splint was manufactured. A computer-aided motion analysis of the patient was conducted (JMA Optic). Full-arch scans of the maxilla and mandible, a biocopy of the maxilla with a bite fork, and buccal scans of the centric jaw relation (Primescan) were performed. The jaw relation was determined beforehand by ballistic closing on a chairside-fabricated anterior jig. The digital construction of a Michigan splint took place in the dental laboratory. The design was nested and milled from a polymethyl methacrylate (PMMA)-containing blank (CLEARsplint Disc). The oral splint was inserted into the patient's mouth and checked to ensure a tension-free fit. The static and dynamic contact relationship was checked. During the follow-up visit, the patient reported an improvement in tension in the masticatory muscles. The described procedure allows for the manufacture of an adjusted oral splint through a purely digital workflow.

Intraoral scanner-based virtual facebow transferring: A chairside dental technique.

Accurately mounting dental casts on an articulator is an essential step in prosthetic treatments. In digital dentistry, virtual articulator mounting procedures rely on virtual facebow records. However, virtual facebow records usually require devices like face scanners or jaw motion tracking systems that are not commonly available in most dental practices. The present technique report describes a straightforward intraoral scanner-based virtual facebow transfer approach. In this technique, a reference facebow joint support was first scanned and aligned with a virtual articulator. Then, a patient's facebow joint support and bite fork assembly were scanned chairside with an intraoral scanner and aligned with the virtual articulator by matching common features with the reference facebow joint support. After aligning the patient's intraoral scans with the patient's bite fork scan that was already superimposed on the virtual articulator, a virtual mounting process was achieved. Once the corresponding reference facebow joint supports have been generated, this technique can be easily implemented with most facebow systems and be seamlessly integrated into daily clinical practice as only an intraoral scanner and a conventional facebow were required.

Custom Ocular Prosthesis with an Innovative Approach of Iris Positioning Using Bite Fork: A Case Report

Custom Ocular Prosthesis with an Innovative Approach of Iris Positioning Using Bite Fork: A Case Report

Proposal of a Full Digital Workflow for a Bite Fork to Assess Mandibular Advancement during Drug-Induced Sleep Endoscopy (DISE) for Obstructive Sleep Apnea

(1) Background. Drug-induced sleep endoscopy (DISE) is currently regarded as the gold standard diagnostic procedure to assess the site(s) of upper airway collapse in subjects affected by Obstructive Sleep Apnea Syndrome (OSAS). During DISE, a jaw thrust maneuver is performed to advance the mandible and to predict the effectiveness of outcomes of treatment with mandibular advancement devices (MADs). However, the maneuver is not predictable and could be influenced by specific patients’ anatomical/functional conditions. The aim of this work is to propose a full-digital workflow for customizing an individual mandibular advancement fork, usable by otorhinolaryngologists during DISE. (2) Materials. Two patients with a diagnosis of mild-to-moderate OSAS (AHI ≥ 5 to ≤30/h of sleep) underwent orthodontic examination to verify the usability of the MAD. Intra-oral scans and registration were performed, including bite registration with 65% of mandibular advancement. The latter measurement was used as a reference to design a 3D-printed fork for DISE, as well as for the future MAD. Both patients underwent DISE in the operating room in the presence of an anesthesiologist, otolaryngologist, orthodontic specialist and neurophysiopathology technician. (3) Results. In the intraoperative polysomnography recording, during sleep, the presence of obstructive apnea was confirmed based on respiratory parameters (PNG1, PNG2, PNG3) with associated desaturation and increased muscle activities on PNG4 (mylohyoid muscle), EMG1 (right masseter muscle) and EMG2 (left masseter muscle). With the advancement fork in place, the immediate improvement effect on all respiratory parameters with normal saturation values and the complete suppression of masseter muscles were observed. Accordingly, both patients were considered potential good-responders to the MAD treatment. (4) Conclusions. The preliminary data shown are encouraging and would suggest that the fork represents a stable reference for the otorhinolaryngologist to evaluate the airway patency within the physiological range of movement. The efficiency of the work-flow from data registration to the DISE procedure and laboratory process represent two significant advantages that justify the integration of a digital system in the management of patients affected by OSAS.

Maximal Bite Force Measured via Digital Bite Force Transducer in Subjects with or without Dental Implants—A Pilot Study

The aims of the current study were as following: (1) to evaluate the maximal bite forces in patients with dental implants versus patients without dental implants, as measured by a digital bite force transducer (GM10); (2) to evaluate the influences of sex, age, and sleep/awake bruxism on the maximal bite forces of the two groups. Forty patients recruited to the study were divided into two groups: test group (“implant”) if they had one or more posterior restored implants and control group (“no-implant”) without the presence of posterior dental implants. A digital bite fork (GM10) was used to measure the bite forces from three posterior occluding pairs in all participants. Differences in the mean values between the test and control groups and between different sexes were evaluated using one-way and two-way ANOVA tests. A cross-tabulation analysis was conducted to identify a trend line between the groups. There was no significant difference in the maximal bite force between the test and control groups (p = 0.422), but the cross-tabulation analysis revealed a clear trend of a stronger representation of the “no-implant” group at higher occlusal forces. A significant difference was detected between the maximal biting forces of male and female subjects (p = 0.030 in the implant group, p = 0.010 in the no-implant group), regardless of the experimental group. The presence of bruxism and clenching did not influence the bite force values (p = 0.953), and a significant difference was not found between the age groups (p = 0.393). Within the limitations of this study, it may be assumed that there was no significant difference between the maximal bite forces between patients with and without dental implants but that there was a trend line implicating a stronger representation of the “no-implant” group at higher forces. In addition, the results revealed a significant sex-related difference in the maximal occlusal force. Further studies with larger sample sizes are warranted.

434 Precision Oral Appliance Therapy: The Prime-Time Treatment for OSA

Abstract Introduction CPAP was previously considered the “gold standard” due to its high efficacy in eliminating obstructive events. Despite improvements in technology, the “effectiveness” of CPAP has been compromised by poor real-world compliance. Technological improvements have improved the “effectiveness” of Oral Appliances. This study reports the efficacy of a novel, precision engineered Oral Appliance for the primary treatment of all severities of OSA. Methods Digital scans and digital bite registrations were recorded with a George Gauge utilizing a a 3mm bite fork. Initial protrusion was set at 40–60% and varied according to the degree of overbite and overjet, the severity of OSA, and the presence or absence of TMJ symptoms. All patients were fitted with a ProSomnus (IA) MAD and titrated according to their subjective symptoms. An efficacy study was obtained with a HST after titration and compared to the initial PSG or HST. Results Outcome data on 85 patients (37 female, 48 males, aged 56.7 +/1 10.2 years) was retrospectively reviewed. The patients were consecutively ordered for follow up data, many patients did not return for follow ups. The pre-treatment AHI was 24.5 +/- 19.1 with 36 patients Mild, 26 Moderate and 23 Severe patients. O2 Nadir was 84.1% +/- 5.5%. Post treatment AHI was 5.5 +/- 4.9 with an AHI reduction of 71.6% +/- 20.3%. 59% of the patients scored <5, 31% 10 on the outcome AHI data. O2 Nadir improved to 88.2% overall. 31 patients had RERA’s (RDI-AHI) >10 with an average of 16.7 +/- 7.5, of these patients 27 saw a reduction of RERA’s of 54.4% from 16.9 to 7.1. Conclusion The data shows that a precision oral appliance is capable of successfully treating patients with all levels of severity, with the majority of patients treated to an AHI<5. 23 severe patients with an average AHI of 49.7 were treated to a final average of 8.6, 4 of the patients scored above 10. Additionally, patients successfully saw a reduction in upper airway resistance airflow as evidenced by a reduction of RERA’s of 54.5%, showing that a precision oral appliance can have a significant impact on the upper airway. Support (if any) None

Bite Force in Elderly with Full Natural Dentition and Different Rehabilitation Prosthesis.

(1) Background: This study aimed to investigate maximum bite force (MBF) in elderly patients with natural full dentition (FD), patients rehabilitated with Traditional Complete Dentures (CD), with overdentures (IRO) and edentulous patients (ED). We also tested whether MBF changes are associated with gender, age of the patients and body mass index (BMI) as result of altered food; (2) Methods: Three hundred and sixty-eight geriatric patients were included. We studied two types of prostheses: (a) IRO with telescopic attachments. (b) CD (heat polymerized polymethyl methacrylate resin). The MBF was measured using a digital dynamometer with a bite fork; (3) Results: We found that MBF is higher in males than females, regardless of teeth presence or absence (p < 0.01). In patients with CD or IRO, there are no differences between males and females; prostheses improve MBF compared to edentulous patients (p < 0.0001) and this effect is greater with IRO prostheses (p < 0.0001); the chewing force of FD subjects remains greater (p < 0.0001); there are no differences among chewing strength based on different BMI categories, although FD subjects have a reduced incidence of obesity; there is a significant negative correlation between MBF and age (p = 0.038; R = 0.145), and no correlation between MBF and BMI; (4) Conclusions: This study showed that MBF improves more in patients using IRO prostheses, although not reaching the MBF of FD subjects. MBF does not correlate with BMI, although we found increased percentages of obesity in edentulous subjects or those with prostheses. Thus, old people wearing prostheses require special attention by a nutritionist to avoid risk of malnutrition.

Higher Maximal Occlusal Bite Force in Endodontically Treated Teeth Versus Vital Contralateral Counterparts

IntroductionDecreased sensitivity to occlusal load could lead to a greater risk of damage to endodontically treated teeth. Therefore, this study aims to test whether root canal treatment reduces the sensitivity of the treated teeth to occlusal load. MethodsThis is a comparative cross-sectional study of 124 patients who received root canal treatment. Treated teeth were compared with vital teeth on the contralateral side. After interviews with participants, their maximal bite forces (MBFs) of their root canal–treated and contralateral untreated teeth were measured using a digital bite fork force transducer. Data were analyzed by comparing the mean MBF of root canal–treated and control teeth. ResultsThe mean MBF (± standard deviation) was 226.6 N (±168.7) for root canal–treated teeth and 207.93 N (±158.08) for control teeth. Root canal–treated teeth had a significantly higher difference in the mean MBF than the control group (P < .0001) using the paired sample t test. A univariate analysis test showed that differences in the MBF were affected by molar relationship, overbite, and the quality of root filling. ConclusionsThe difference in the MBF was significantly higher in root canal–treated teeth, which is consistent with the function of dental pulp as a highly sensitive sensor. Therefore, the reduction in the sensitivity of teeth to an applied load after pulp removal may increase the risk of overloading. This may, in turn, increase the frequency of tooth damage after root canal treatment.

The use of a bite fork to help mobilize the maxilla after downfracture during the Le Fort I osteotomy. A technical note

The Le Fort I osteotomy is indicated to reposition the maxilla in the surgical correction of dentofacial deformities. Although it is a known surgical step, like any surgical procedure, it can have complications and difficulties; among these, the initial mobility of the jaw is very common after completing all corticotomies. The authors present a technique in which the bite fork is used as an auxiliary tool in maxilla downfracture, especially in cases of maxillary impaction where vertical space is created on the walls of the corticotomy. As the bite fork acts as a scraper with a long leverage arm, an advantage would be the better distribution of forces along the corticotomy, minimizing the risk of bad fracture and facilitating maxillary downfracture movement.

Influence of muscle contraction and jaw movement speed on the estimation of chewing force from elevator muscle EMG

Recent studies have shown that an additional muscle activity (AMA) in chewing was responsible for excessive masticatory forces that had been estimated from isometric bite force–activity relations. Our aim was to test the thesis that this AMA could be identical to the speed-dependent ‘anticipatory activity’ that was found in symmetrical jaw closing (Abbink et al., 1999). In this case, forces estimated from EMG should be realistic for slow mastication, but should strongly increase with faster chewing movements. In 56 dentate volunteers the activities of bilateral masseter and anterior temporal muscles were measured during (a) right-sided chewing, (b) right-sided isometric clenching on a bite fork with alternating loads. These biting tasks were carried out with slow, habitual and fast contraction/movement speeds (30, 64, 102 cycles min−1). Masticatory forces were estimated for each speed by putting activities found in task (a) into bite force/activity relations obtained from task (b). In slow and habitual mastication, activities of the working side masseter were equal and exceeded the corresponding clenching activities by factors of 2·8 and 2·4, respectively (P < 0·001). Consequently, forces estimated from slow (680 N) and habitual (695 N) chewing did not differ significantly and were unrealistically high. These estimated forces and hence the corresponding AMAs did not depend on the speed movement in the same way as the anticipatory activity described inAbbink et al. (1999). In contrast, forces estimated from fast chewing (811 N) were significantly higher (P < 0·001) and corresponding AMAs qualitatively behaved like anticipatory activities. In conclusion, the AMA in chewing could be explained by anticipatory muscle activity for high movement speeds. In slow and habitual chewing however, the AMA may contain amounts of activity with a different origin.

A novel sensor for bite force determinations

Objectives. The clinical usefulness, accuracy and precision of a novel bite force sensor based on force sensing resistors were tested in six subjects wearing maxillary removable partial dentures retained by conical crowns. Methods. The surfaces of the sensor were manufactured in a silicone material that had mechanical properties similar to those of tough foodstuffs. In two separate series of standardized bite force tests, submaximum force levels were recorded with the sensor and with a strain gaged bite fork. Subjects were assisted in the loading tests with visual feedback instrumentation. Reliability estimates for the bite force sensor were calculated in order to show their reproducibility. Strain gages attached to the prostheses were used to determine the pattern of force distribution during loading tests. The bite force results obtained with the new bite force sensor and with the bite fork were analyzed with ANOVA and Scheffés tests. The strain patterns registered with strain gages were analyzed with F-test. Results. The bite force sensor and the bite fork transducer showed no statistically significant differences in respect of intra-individual bite force levels (range 50–300 N). The bite forces registered with the new sensor were dependent on the loading position ( p<0.05), sex ( p<0.05) and test subject ( p<0.05). The reliability of the new sensor for submaximum bite forces was calculated to be 93%. Strain gage results showed that the new sensor generated strain patterns of less variance ( p<0.05) than the bite fork and therefore allowed for higher precision during biting tests. Significance. The presented instrument has such clinical merits, as to favor its use in experimental clinical studies on the biomechanics of prosthetic appliances.

Measuring system for in vivo recording of force systems in orthodontic treatment–concept and analysis of accuracy

The aim of our developments is three-dimensional in vivo recording of those orthodontic force systems inducing tooth movements during treatment with fixed appliances. The concept presented here is the first to permit the forces and torques of these statically multiply undetermined systems to be recorded in vivo. For this purpose the force systems transmitted to the teeth from the archwire are isolated from the respective tooth by means of divisible special-design brackets and introduced into a 3D force–torque sensor via a gripping appliance. The sensor is fixed with a purpose-developed device relative to the patient’s dental arch. The patient’s head is positioned relative to the system by means of a bite fork as well as a forehead and chin support. Electrical measurement of the mechanical quantities is carried out by a six-axis force–torque sensor with semiconductor strain gauge elements, an electronical evaluator and a mobile measuring computer (PC). Extensive calibration of the sensor system has shown that the measuring uncertainty of the electrical measuring is less than 2%. Precise spatial fixing of bracket slot and archwire in the therapeutic position is crucial to the measuring accuracy of the system, as even minimum displacements affect the force system to be measured. Movements of the measuring system up to 0.04 mm result from a therapeutic force of 1.5 N. The results of extensive in vitro studies have already demonstrated that the system developed by us is suitable for the specified in vivo measuring function.

A new method to simplify and increase the precision of maxillary cast mounting procedures in fully adjustable or semiadjustable articulators

This study introduces a new impression procedure that permits mounting the maxillary stone cast in an articulator for any patient treatment and is applicable to any dental arch with any impression material. A transfer tray was designed that makes it possible to transfer the patient's maxillary impression to the articulator in a one-stage procedure without the need for making record bases and occlusion rims or the need to use a face-bow bite fork. (J Prosthet Dent 1997;77:219-24.)

Bite fork modification

Retention of registration material is a common problem with bite forks that are smooth and do not have retentive elements such as grooves or holes (Fig. 1). A bite fork disk was recently introduced (Bite-Tab, Panadent Corp., Grand Terrace, Calif.) that is made with standard red impression compound. The disks are attached to self: adhesive plastic strips for application and removal from the bite forks. The manufacturer states that they can be used on most standard bite forks commercially available. The Bite-Tab disk addresses the problem of retention for the face-bow registration material on this type of bite fork. This problem can be corrected without purchasing Bite-Tab disks and by drilling three 8 to 10 mm diameter holes through the bite fork (Fig. 2). The sharp edges around the holes must be rounded to prevent edge stress from brealdng the impression compound. An impression compound is heated to its worldng characteristics, placed over the holes, and a face-bow registration is made. The holes allow the impression compound to flow to the inferior surface of the bite fork. The patient's mandibular teeth can be used to stabilize the bite fork to prevent it from moving. A heavy-body polyvinyl siloxane or bite registration paste could be substituted for the impression compound.

Simultaneous Bimaxillary Orthognathic Surgery

Simultaneous bimaxillary orthognathic surgery, which can alter an occlusal plane, is employed for correction of varying maxillomandibular dentofacial deformities. Since positioning of the maxillary segment is inherently considerable to improve both facial esthetics and occlusion, a systematized and ensured procedure is needed to obtain stable results.The authors describe here the bimaxillary surgical procedures with special reference to a newly devised “Two-Step positioning” of the maxillary segment utilizing face bow transfer and an occlusal plane indicator.The Two-Step positioning technique is summarized as follows:1) An altered occlusal plane of the maxilla in model surgery is recorded in a Quick mount face bow (Whip-mix Co.). Beforehand the dental arch impression made with self-curing resin and small hooks at bilateral premolars is attached to the bite fork, which securely holds the mobilized maxillary segment on the bite fork during surgery.2) Step 1: After mobilizing the mandible and maxillary segment, the maxillary occlusal plane is transfered to the patient by means of face bow transfer. The maxillary segment is immobilized with two low profile miniplates (Leibinger Co.).3) Step: The occlusal plane indicator having an upper dental arch impression is applied to the dental arch, which enables easy assessment of the occlusal plane three-dimensionally. In case indicating additional correction of the plane, loosening some screws of the miniplate allows versatility in repositioning of the segment.This technique has been applied to 30 cases without incidence, and it has been our experience that positioning of the maxillary segment is ensured and the surgical procedures are systematized with this technique.

全上下顎骨同時移動術における顔弓を用いる上顎骨骨片位置決定法

It is very important to reposition and to keep the occlusal plane in harmonious relation to TMJ and the skull in two jaw surgery. In addition, the surgery should be performed as accurately as the presurgical planning.However, it is not always easy to satisfy the above-mentioned items in deformities indicating sagittal, transverse and vertical dysplasia or discrepancy of maxilla and mandible. For this reason, we have performed the method of intra-operative repositioning of the Le Fort I osteotomized maxilla according to the pre-operative planning by using the semi-adjustable articulator SAM or Whip-Mix facebow. We use routinely the simultaneous jaw movement by Le Fort I and sagittal splitting osteotomy for two jaw surgery.The maxillary position determined by preplanning of the cephalometric prediction tracing and model operation is recorded with the facebow. After the recording, the facebow with the bitefork is removed from the articulator, and is sterilized with gas to be ready for the intraoperative transfer.The maxilla is adequately mobilized as usual, the vertical dimensions of maxilla are reduced to the same extent as the model operation. The osteotomized maxilla is inserted into the bite fork. Then, the facebow is adjusted to the external auditory canal.In addition, intermaxillary wiring is performed after the mandible is also inserted into the bitefork. Once the facebow is fixed by the nasion locator, the facebow system is kept rigid and free from distortion.The characteristics or advantages and the indication of this facebow transfer system are as follows:1. This system using the Whip-mix or the SAM facebow guarantees precise transfer from the articulator to the patient.2. It has the possibility of obtaining intra-operatively accurate reproduction of the position of osteotomized maxilla in relation to the skull, the mandibular teeth arch, and the TMJ as preplanned.3. It has the possibility of keeping the transferred position and stabilizing maxilla with the mini-plates without freehanding.4. As this system is a “step by step” technical procedure, the laboratory workup is very important.5. The model operation in this system is for the oral surgeon operation training.6. The indication of this system seems to be facial asymmetry or long face with mandibular protrusion.We have performed this facebow transfer system on 14 patients and obtained good results. All patients currently have acceptable results.

Endurance tests of the masticatory system on different bite force levels.

Endurance tests of the masticatory system were performed in three different groups of healthy volunteers in order to investigate the relation between bite force and endurance time on different force levels. The subjects clenched a bite fork until exhaustion. Some tests were performed with and others without visual feedback of the exerted force. It was found that the subjects could sustain the maximal bite force practically at the same level during the recording time with visual feedback. The exerted force varied during the non-feedback recordings and generally decreased on the forceful levels. The average endurance time increased at lower bite force levels and the relation between force and endurance time is described. The average integrated time-force areas did not differ between the test levels. It is concluded that endurance tests in the clinic may be performed on submaximal bite force levels.

Replicability of electromyographic recordinds of the masseter muscle during mastication

This study evaluates the reliability of a method to duplicate the location of surface electrodes for recording the electromyographic activity of masseter muscles during mastication and quantifying the activity by a micro-computer system. A plastic framework consisting of a bite fork and electrode positioners was used to place the electrodes by relating the positioners to an occlusal index and keeping this relationship constant at subsequent sittings. EMG recordings were repeated on two different days for each of 10 subjects while they performed standardized masticatory performance tests with peanuts and carrots. The muscle activity recorded with hardware integrators was an average of 26.7% of the computerized software integrations but measures derived from the two methods of integration were highly correlated ( r = 0.965) and yielded similar results. Significant correlations were found between test sessions for each measure of masticatory performance and integrated EMG activity for ipsilateral and contralateral muscles. For each subject, no significant differences were found between sessions for any masticatory performance or EMG variable. The results indicate that reliable inter session EMG recordings during mastication can be made by using the template for positioning of the electrodes. In addition, the microcomputer data acquisition system provides results comparable to those obtained with conventional hardware integrators, with the added benefit of providing information on each individual stroke and its various components.

Relationship between myoelectric activity in masticatory muscles and bite force.

Myoelectric activity in the anterior and posterior temporalis and in the masseter muscle was assessed in five subjects biting unilaterally on a bite fork at 50, 100 and 200 N for 60 s. The bite fork was placed between the right first premolars and the first molars. The ipsilateral muscle activity was recorded first, and the contralateral side was evaluated 1 wk later. The relationship between exerted force and EMG-activity was expressed as ratios between EMG-activity and related bite force. EMG-activity increased with increasing force for all muscles tested. Linearity was found for the anterior temporal muscle, but not for the other muscles. Four of the subjects participated in an endurance test, exerting maximum bite force on the right side for as long as possible. The EMG activity of the right masseter muscle was closely related to bite force, in contrast to the other tested muscles. The activity of the left muscles increased at the end of the endurance test.

A photographic method of assessing swelling following third molar removal

No objective method for measuring postoperative swelling both simply and reliably is known from the literature. The method described in this article measures the degree of swelling indirectly by comparing tracings of pre- and postoperative photographs printed full-size. The photographs taken are standardized and full-face. The head is reproducibly fixed by means of a bite impression and two rings. One ring is mounted on a table on which the camera also is fixed. At the other, mobile, ring the bite impression is fixed. Three-point contact in the correct position between the two rings is signalled electrically, so that the head is in the correct position and the photograph can be taken. The advantage of this method over a rigid connection between bite fork and fixation stand on the table is that distortion or even bending of the fork and connecting bar is not possible. Experience with this method shows that in 95 % of the patients photographed the picture was exactly reproducible. Measuring non-operated test persons revealed the reproducibility of the cheek contour to be better than 0.2 mm. The error made when tracing the photographs is of about the same magnitude.