Occlusal Contact Force Research Articles

Clinical applications of the T-Scan quantitative digital occlusal analysis technology: a systematic review.

Occlusion is associated with all disciplines of dentistry and plays a major role in the longevity of both implant- and tooth-borne restorations. Achieving occlusal harmony ensures balance is established between the dental and myofascial structures, which can be measurably established to high numerical tolerances with the T-Scan digital occlusal analysis system. To describe and evaluate the known and proven applications of T-Scan digital occlusal analysis in various dental practice disciplines through a systematic review of the literature. An electronic, English-language PubMed/MEDLINE and Cochrane Central Registry of Controlled Trials database search using the keywords "T-Scan," "TMD," "Occlusion," "Implant Protected Occlusion," and "Orthodontics" was conducted without any date restrictions. The related journal findings were hand searched to determine studies that met the eligibility criteria for inclusion in the present systematic review. The PubMed/MEDLINE search identified 423 articles. After removing duplicates, the titles and abstracts of the remaining 421 studies were screened. 274 ineligible articles were excluded, leaving 147 articles. Of those, 33 articles were not in English, 27 full-text articles were not available, 4 were comments and letters to editors, 1 was a review, and 2 described techniques. A total of 86 articles met the eligibility criteria for inclusion. Much scientific evidence supports the use of T-Scan, as it measures relative occlusal contact forces and the time sequence durations of occlusal contacts objectively, accurately, and repeatedly for improved treatment outcomes. The system's hardware, sensor, and software evolution from T-Scan I to today's T-Scan 10 Novus system has overcome early sensor and system drawbacks to improve the clinical performance of T-Scan in many disciplines of dental medicine.

Comparison Between Maximum Bite Force on First Molar with Prosthesis and Contralateral First Molar Without Prosthesis

Background: Bite force is an indicator of the functional state of the masticatory system that results from the action of jaw elevator muscles modified by the craniomandibular biomechanics. Bite force measurement is essential in dental treatment as an extreme bite force on tooth may affect health of periodontium and increase risk of prosthesis fracture. A patient with low biting force may be helpful for the successful long-term outcome of prosthesis. A variety of devices has been used to record human bite force. Nowadays, sensitive electronic devices are used those are both accurate and precise enough. Recently, T-scan has been more popular to record the pattern of occlusion. The T-scan system precisely and dynamically records the occlusal contact time, force, and area in percentage. T-scan identify both force and timing which are the most fundamental parameters for measuring occlusion. The present study was designed to compare maximum bite force on first molar with prosthesis and contralateral first molar without prosthesis by using T-scan. Objectives: To compare maximum bite force (MBF) on first molar with prosthesis and contralateral first molar without prosthesis. Materials and Methods: This quasi-experimental type study was conducted in the Department of Prosthodontics, BSMMU. The patients were selected by a consecutive sampling technique, requiring permanent restoration in endodontically treated first molar on one side and natural first molar on contralateral side. The selected tooth was prepared for full veneer crown following standard procedure with armamentarium. Symptomless patients up to 3 months were measured bite force on cemented prosthesis and contralateral natural tooth. Bite force was measured with T-scan for three times with 30 sec interval and highest value was recorded in a data collection sheet for each patient to compare maximum bite force on first molar with prosthesis and contralateral first molar without prosthesis in the same patient. Result: The maximum bite force at the first molar without prosthesis was 14.30 ±4.2% and first molar with prosthesis was 12.05 ±3.55%. Tooth without prosthesis maximum bite force was significantly more than the tooth with prosthesis. Conclusion: Maximum bite force was significantly higher in tooth without prosthesis than the tooth with prosthesis. The difference of maximum bite force was not statistically significant in relation to gender, age and BMI.

Repeatability and reproducibility of 2 digital occlusal analyzers for measuring the right- and left-side balance of occlusal contact forces: An in vitro study

Statement of problemAlthough different digital occlusal analyzers have been marketed, comparative studies are lacking. PurposeThe purpose of this in vitro study was to compare the repeatability and reproducibility of 2 different digital occlusal analyzers (T-Scan and OccluSense) for measuring the right- and left-side balance of occlusal contact forces. Material and methodsThe repeatability and reproducibility of the 2 digital occlusal analyzers for measuring the balance of occlusal contact forces were determined and compared by using the Gauge Repeatability and Reproducibility tests based on the International Organization for Standardization (ISO), ISO 5725-2 and ISO 5725-3 standards. Ten different dental casts were mounted in the maximum intercuspation position on a semi-adjustable articulator. Then, the balance of occlusal contact forces in each of the 10 articulated dental casts was measured 24 times with each of the 2 digital occlusal analyzers. In addition, as the OccluSense, unlike the T-Scan, does not have a centering support for the piezoelectric film sensor, measurements with it were performed without and with a custom-designed and manufactured centering support. Finally, the repeatability and reproducibility of both digital occlusal analyzers were determined and compared using the Gauge Repeatability and Reproducibility tests. ResultsThe repeatability and reproducibility tests revealed that only 0.8% of the variance of the measurements obtained with the T-Scan was due to repeatability and reproducibility (0.4% repeatability, 0.4% reproducibility). In contrast, 12% of the variance of the measurements obtained with the OccluSense was due to repeatability and reproducibility (2.2% repeatability, 9.8% reproducibility). However, when using OccluSense with the centering support, the variance decreased to 6.4% (2.8% repeatability, 3.6% reproducibility). According to the Automotive Industry Action Group classification, the repeatability and reproducibility of the T-Scan were good, those of the OccluSense poor, and those of the OccluSense with the centering support medium. ConclusionsThe repeatability and reproducibility of the T-Scan were significantly better than those of the OccluSense for measuring the balance of occlusal contact forces. Furthermore, the repeatability and reproducibility of the OccluSense were significantly improved when used with a device to center the piezoelectric film sensor between the incisors. Nevertheless, the repeatability and reproducibility of the T-Scan were better.

Positional influence of center of masticatory forces on occlusal contact forces using a digital occlusal analyzer

Statement of problemDigital occlusal analyzers allow the recording of dental contact forces. Some authors assume a unique location for the center of contact forces at the position of maximum intercuspation, while others indicate variations in dental contact forces when recorded at different times of the day. Which approach is more appropriate is unclear. PurposeThe purpose of this in vitro study was to analyze whether a change in the balance of masticatory forces influences the location of the center of contact forces and its magnitude. Material and methodsThree different dental casts, selected under dental criteria, were mounted in maximum intercuspation on a semiadjustable articulator equipped with a pattern indicating 9 different force application points (intersection point between 3 longitudinal rows and 3 transverse columns). A force of constant magnitude (169 N) was applied 10 times at each of the application points, and occlusal forces were recorded with a digital occlusal analyzer. Then, two variables were studied: the location of the center of contact forces and its magnitude. Each force application position (9 positions × 3 dental casts=27 in total) was repeated 10 times, and measured data were statistically analyzed with 2-way repeated measures ANOVA (α=.05) test. ResultsThe repeatability of the method indicated that the coefficient of variation mean was 0.37% in the location of the center of contact forces and that its magnitude was 3.70%. The 2-way repeated measures ANOVA test revealed statistically significant variations in the location of the center of contact forces and its magnitude, revealing that longitudinal changes of the application point of masticatory forces affected the magnitude of contact forces and that longitudinal and transverse changes of the application point of masticatory forces affected the location of the center of contact forces. ConclusionsThe location of the center of contact force and its magnitude provided by a digital occlusal analyzer at the position of maximum intercuspation are not necessarily unique to each articulated dental cast. Even if the intensity of the masticatory force remains unchanged, changes in its lateral or longitudinal balance also influence the result of the occlusion forces.

Orthodontic treatment of children with anterior open bite and posterior crossbite: An analysis of the stomatognathic system.

Dental malocclusions are deviations from normalities due to the inadequate growth and development of the dental arch which provides functional changes to the stomatognathic system. The aim of this longitudinal study was to evaluate the electromyographic activity (EMG) the masseter and temporalis muscles, strength of the orofacial tissues and occlusal force of children with anterior open bite (n=15) and posterior crossbite (n=20), 7 days after the removal of the orthodontic apparatus. A fixed horizontal palatal crib was used in the treatment of anterior open bite and the fixed appliances Hyrax or MacNamara was used in the treatment of posterior crossbite. EMG of the masticatory muscles was recorded using an electromyograph with wireless sensors during mandibular tasks. Habitual chewing was assessed using the integral of the linear envelope of the electromyographic signal in the masticatory cycles. The strength of the tongue and facial muscles was measured using the Iowa Oral Pressure Instrument. T-Scan was used to analyze the force of occlusal contact. Molar bite force was measured by digital dynamometer. Significant differences (p<0.05) were found in the EMG data of the masseter and temporalis muscles in the static and dynamic mandibular tasks. There were no significant difference in strength of orofacial tissues, occlusal contact force and molar bite force 7 days after the removal of the orthodontic apparatus. The results of this study suggest that the orthodontic treatment of anterior open bite and posterior crossbite in children promoted functional alteration in the electromyographic activity of masseter and temporalis muscles.

The effects of a periodontal ligament analogue on occlusal contact forces

Previous bench-top studies examined the details of the mechanical environment of rigidly fixed occluding teeth. It was demonstrated that during each chomp, contacting molar teeth experience in-occlusal-plane forces (Flateral ) that are highly transient in magnitude and direction. The objectives of this study are to identify Flateral behaviours that are attributable to the presence of a visco-elastic periodontal ligament (PDL) analogue, and to assess the necessity of incorporating it into future studies. A weighted maxillary molar denture tooth was lowered onto, and raised from, a matching mandibular molar 10 times. The latter was supported by a load cell that continuously measured Flateral . For statistical purposes, the test was repeated with 21 (n=21) different occlusal relationships obtained with 0.05mm incremental shifts of the lower assembly. Overall, the results are similar to those of rigid attachment but the details of the Flateral profiles are very different. The PDL plays a major role in the mechanical environment of occlusion, suggesting that, in general (not necessarily always), it should be integrated into studies of occlusion.

Computerized occlusal analysis of two different removable retainers used during retention phase- A Randomized controlled trial

ABSTRACT Aim: To evaluate and compare occlusal contact force distribution, occlusion time and disclusion time following wear of Begg’s wrap around retainer and Vacuum formed retainer after completion of orthodontic treatment using a T-scan III. Materials and Methods: Twenty subjects after completion of active orthodontic treatment were randomly allocated into two groups, Group I – Begg’s wrap-around retainer (n-10) and Group II–vacuum formed retainer (n-10) one patient was lost to follow up in each group and the final sample size assessed at T1 in each group was 9. T-scan III was used at two-time intervals, T0 – first scan taken immediately after debonding and T1 – taken during retention any time between 10 and 12 months. Comparison of parameters within the groups was done using paired t-test and comparison between the groups was done using independent t-test. Results: No statistically significant difference in the distribution of occlusal contact forces was noted in both groups at T0 and T1 (p value<0.05). Disclusion time reduced in both groups at T1 but a statistically significant reduction in the disclusion time of left lateral excursive movement and protrusive movements (p value<0.05) was noted (T0-T1) in Group I. Statistically significant increase in the occlusion time was noted in Group II (T0-T1) at T1 between the two groups. Conclusion: No differences in occlusal contact force distribution was noted within and between the two groups. Disclusion time reduced in subjects on Begg’s wrap around retainers indicating favourable muscle activity and Occlusion time increased in subjects on vacuum formed retainers.

Computerised occlusal analysis of mini-dental implant-retained mandibular overdentures: A 1-year prospective clinical study.

Occlusal analysis is a substantial tool for the functional improvement evaluation after using implant-retained overdenture comparing to complete denture without dental implant retaining. To evaluate occlusal pattern, chewing force distribution in mini-dental implant-retained mandibular overdentures by computerised occlusal analysis system and to compare patient satisfaction after 1-year function. Thirty-one patients wearing complete dentures were included in the study. Prior to mini-dental implant-retained treatment, all patients were assessed for occlusion and force distribution using computerised occlusal analysis system (T-Scan® ), and then, all patients received two mini-dental implant-retained mandibular overdentures. Mini-dental implants were immediately loaded using low vertical profile attachments (Equator® ). T-Scan® was used to evaluate chewing force and force distribution at 1day, 3months, 6months and 12months. The patient satisfactions before implant placement and after 1year were evaluated using questionnaires which included satisfaction of denture quality, psychosocial behaviour and chewing efficiency modified from the validated questionnaires. Clinical evaluation of two mini-dental implant-retained mandibular overdentures showed 100% success rate after 1year. T-Scan® demonstrated that maximum occlusal contact force increased continuously. The force distribution; the tooth contact number increased over the period. At 1-year follow-up, overall patient satisfaction was significantly greater than before receiving mini-dental implant treatment (P<.001). Using computerised occlusal analysis, mini-dental implants improve complete denture function significantly in terms of maximum occlusal contact force, tooth contact number without the impairment of force distribution. The oral function of the patients has been enhanced.

The combined effects of salivas and occlusal indicators on occlusal contact forces.

Some occlusal detection products are designed for use on dry teeth, but this is not always achieved. Others are suited for dry and wet applications. The objective of this study is to assess the combined effects, on occlusal contact forces, of two previously studied affecting variables-occlusal detection products and saliva. We used a full-arch dentiform with three occlusal detection products (an articulating film, an articulation paper and T-Scan) in combination with human (HS) and an artificial saliva. The maxillary arch assembly, weighing ~54N (the maximum bite force), was lowered onto (occlusion) and lifted off (disclusion) of the mandibular arch through 10 cycles by a mechanical testing machine. The forces and moments acting on the mandibular arch were continuously recorded by a load cell that supported it. The maximum values of Flateral (the in-occlusal plane component of the occlusal contact force) were analysed by occlusion/disclusion separately using one-way ANOVA, with factor for group type to identify the significant effect of salivas on products, effect of products, effect of salivas with products, effect of human saliva. A difference in occlusion and/or in disclusion was considered different. Statistical differences (P<0.0001) in Flateral were found in: dry product vs product + HS, dry product vs product + artificial saliva (with articulating film and T-Scan) and HS vs product + HS (with articulation paper and T-Scan). All products were affected by the salivas, except articulation paper by artificial saliva.

Does the presence of an occlusal indicator product affect the contact forces between full dentitions?

Studies have explored occlusal marking interpretation, repeatability and accuracy. But, when an occlusion detection product is interposed between teeth, direct tooth-tooth occlusal contact relationships are replaced by tooth-material-tooth structures. Thus, the marks cannot reflect the original contacts. This has been shown for single tooth pair contacts. The purpose of this laboratory study was to similarly examine full dentitions. A dentiform was set into Class I centric occlusion with the mandible supported by a load cell. The maxillary arch was guided by precision slides. As the weighted (~52 N) upper assembly was lowered onto and raised off the mandibular arch, the loads on the mandible were measured. With and without (control) occlusal marking material, the steps were as follows: (cleaning - control 1 - material 1) … (cleaning - control 6 - material 6). The six materials were as follows: Accufilm I and II, Rudischhauser Thick and Thin, Hanel Articulating Silk and T-Scan. Then, the six sets of (cleaning - control - material) measurements were repeated with the mandibular assembly shifted, in turn, by 0·1 mm in the Anterior, Posterior, Right and Left directions. The five (Centric and four 0·1 mm shifted) occlusal relationships produced grossly different tooth-tooth (control) load profiles. And, in general, these controls were affected, in different ways, by the marking products. Among the five conventional products, the Rudischhausers fared the worst and the electronic T-Scan was an extreme outlier. Thus, in general, popular occlusal detection products alter the occlusal contact forces, and therefore, their markings cannot characterise the actual occlusion.

Changes in occlusal function after extraction of premolars: 2-year follow-up.

To determine the effects of extraction and the number of teeth extracted on changes in occlusal function by measuring occlusal contact area and force before and after orthodontic treatment with a fixed appliance. Female patients treated with a fixed appliance were divided into nonextraction (n = 36), two maxillary premolar extraction (n = 31), and four premolar extraction (n = 18) groups. Bite pressure-sensitive films were used to analyze the occlusal contact area and force. Measurements were performed before treatment (Pre-Tx), immediately afterward (After-Tx), and 2 years later (2Y After-Tx). The data were analyzed using a linear mixed model and the post hoc Bonferroni test. The occlusal contact area and force after treatment decreased significantly compared with Pre-Tx values but were increased 2 years later in all groups. There were no significant differences in occlusal contact area or force during the entire observation period among the three groups (P > .05). The occlusal contact area and force in the nonextraction and two maxillary premolar extraction groups recovered to Pre-Tx levels 2 years later (P > .05). The occlusal contact area in the four premolar extraction group was significantly lower than the Pre-Tx level after 2 years of retention (P < .05). The occlusal contact area and force showed a tendency to decrease immediately after treatment and then gradually increase to pretreatment levels during the observation period. However, the occlusal contact area did not recover fully after 2 years in the four premolar extraction group.

Digital analysis of occlusion using T-Scan III in orthodontics

Disclusion Time Reduction (DTR) is an objective treatment protocol using T-Scan III (Digital Analysis of Occlusion) for Force Finishing in Orthodontics. Chronic Occluso-muscle Disorder is a myogenous subset of Temporomandibular Disorder symptoms (TMD) can occur to most of post orthodontic cases, if they are not force finished. These muscular symptoms are induced within hyperactive masticatory muscles due to prolonged Disclusion Time, occlusal interferences, and occlusal surface friction that occurs during mandibular excursive movements. This article describes a gadget T-Scan III which can be used for this purpose; whereby measured pretreatment prolonged Disclusion Time can be reduced to short Disclusion Time using the ICAGD enameloplasty, guided by T-Scan occlusal contact time and force analysis.

Clinician accuracy when subjectively interpreting articulating paper markings

Aims:The aim of this study was to determine whether Subjective Interpretation of paper markings is a reliable method for identifying the relative occlusal force content of tooth contacts.Methodology:295 clinicians selected the “Most Forceful” and “Least Forceful” occlusal contacts in six occlusal-view photographs of articulating paper marks that were later compared against computerized occlusal analysis relative occlusal force measurements of the same tooth contacts. Means and standard deviations were calculated by years in clinical practice and by number of occlusion courses taken. A Chi-square analysis was also performed.Results:The mean correct for 295 participant dentists was 1·53 (±1·234). There were no significant differences found for years in practice (P>0·16) or number of occlusion courses taken (P>0·75). The Chi-square analysis showed a sensitivity of 12·6%, a specificity of 12·4%, a positive predictive value of 12·58%, and a negative predictive value of 12·42%. Chance was calculated at 12·5% correct.Conclusions:Subjective Interpretation is an ineffective clinical method for determining the relative occlusal force content of tooth contacts. The reported low scores obtained from a large group of participant dentists suggest clinicians are unable to reliably differentiate high and low occlusal force from looking at articulating paper marks. This longstanding method of visually observing articulating paper marks for occlusal contact force content should be replaced with a measurement-based, objective method.

Daily chewing gum exercise for stabilizing the vertical occlusion

We investigated the effects of a chewing gum exercise program on occlusal conditions and evaluated compliance of subjects. Thirty-five healthy adult volunteers (26 males and nine females) were asked to chew gum for 10-15 min before or after three meals daily for four weeks. Occlusal conditions were recorded as occlusal parameters, such as occlusal contact area, occlusal contact force, and pressure using dental prescale films. These parameters were evaluated by an Occluzer before the exercise period commenced, after four weeks of exercise, and then one month after the end of the exercise period. These parameters were statistically compared using one-way ANOVA. We found that: (i) after four weeks of exercise, anterior and posterior occlusal contact areas and forces were significantly (P < 0.05) increased and the increments were significantly (P < 0.05) higher in the anterior occlusal contact area and force than in the posterior occlusal contact area and force, (ii) the anteroposterior ratio of occlusal contact area and force increased, but not markedly, (iii) increased parameters had significantly (P < 0.05) decreased within one month after the end of the four-week exercise period, (iv) most participants did not complain for discomfort or stress during the exercise. The chewing gum exercise program could increase occlusal contact area and force and also move the anteroposterior occlusal balance forward. Patient compliance with the exercise is likely high enough to keep them exercising.

Determining a Relationship Between Applied Occlusal Load and Articulating Paper Mark Area

Articulating paper mark size has been widely accepted in the dental community to be descriptive of occlusal load. The objective of this study is to determine if any direct relationship exists between articulating paper mark area and applied occlusal load. A uniaxial testing machine repeatedly applied a compressive load, beginning at 25N and incrementally continuing up to 450N, to a pair of epoxy dental casts with articulating paper interposed. The resultant paper markings (n = 600) were photographed, and analyzed the mark area using a photographic image analysis and sketching program. A two-tailed Student’s t-test for unequal variances compared the measured size of the mark area between twelve different teeth (p < 0.05). Graphical interpretation of the data indicated that the mark area increased non-linearly with increasing load. When the data was grouped to compare consistency of the mark area between teeth, a high variability of mark area was observed between different teeth at the same applied load. The Student’s t-test found significant differences in the size of the mark area approximately 80% of the time. No direct relationship between paper mark area and applied load could be found, although the trend showed increasing mark area with elevating load. When selecting teeth to adjust, an operator should not assume the size of paper markings, accurately describing the markings’ occlusal contact force content.

Determining a Relationship Between Applied Occlusal Load and Articulating Paper Mark Area

Articulating paper mark size has been widely accepted in the dental community to be descriptive of occlusal load. The objective of this study is to determine if any direct relationship exists between articulating paper mark area and applied occlusal load. A uniaxial testing machine repeatedly applied a compressive load, beginning at 25N and incrementally continuing up to 450N, to a pair of epoxy dental casts with articulating paper interposed. The resultant paper markings (n = 600) were photographed, and analyzed the mark area using a photographic image analysis and sketching program. A two-tailed Student’s t-test for unequal variances compared the measured size of the mark area between twelve different teeth (p < 0.05). Graphical interpretation of the data indicated that the mark area increased non-linearly with increasing load. When the data was grouped to compare consistency of the mark area between teeth, a high variability of mark area was observed between different teeth at the same applied load. The Student’s t-test found significant differences in the size of the mark area approximately 80% of the time. No direct relationship between paper mark area and applied load could be found, although the trend showed increasing mark area with elevating load. When selecting teeth to adjust, an operator should not assume the size of paper markings, accurately describing the markings’ occlusal contact force content.

An In Vitro Study of Implant-Tooth-Supported Connections Using a Robot Test System

Many unsolved problems in dental implant research concern the interfacial stress distributions between the implant components, as well as between the implant surface and contacting bone. To obtain a mechanical understanding of how vertical and horizontal occlusal forces are distributed in this context, it is crucial to develop in vitro testing systems to measure the force transmission between dental implants and attached prostheses. A new approach to such testing, involving a robotic system, is described in this investigation. The system has been designed to produce simulated mandibular movements and occlusal contact forces so that various implant designs and procedures can be thoroughly tested and evaluated before animal testing or human clinical trials. Two commonly used fixed prosthesis designs used to connect an implant and a tooth, a rigid connection and a nonrigid connection, were fabricated and used for experimental verification. The displacement and force distributions generated during simulated chewing activities were measured in vitro. Force levels, potentially harmful to human bone surrounding the connected dental implant and tooth, were analyzed. These results are useful in the design of prostheses and connecting components that will reduce failures and limit stress transfer to the implant/bone interface.

A robotic system for testing dental implants

Previous studies have attempted to predict the manner in which potentially harmful levels of force are transmitted to human bone surrounding dental implants and adjacent teeth. However, the analysis models previously used are dependent on unknown biomechanical behaviors. In order to develop in vitro testing to measure the force transmission between dental implants and attached prostheses, an accurate simulation of the chewing motion is crucial for data validation. This paper proposes a new approach involving a robot simulation system. The system has been designed to produce simulated mandibular movements and occlusal contact forces so that various implant designs and procedures can be thoroughly tested and evaluated. This paper describes the various components and operation of the test apparatus, including sample results. The primary components of the system are a robot, a test fixture and a measurement system. The robot is a commercially available robot with four primary degrees of freedom. The current technique used to teach the robot mandibular motion trajectories is based on the use of a dental articulator (Wang et al., in Proceedings of the 4th National Applied Mechanics and Robotics Conference, AMR95-094, 1995) [1]). The articulator is then replaced by the actual test specimen consisting of a simulated lower jaw mounted to the robot base and a simulated upper jaw mounted to the robot end effector. A set of noncontact displacement probes are used to measure lower jaw–implant deformations during simulated chewing. A multi-axis force–torque sensor is mounted on the end effector for measurement and feedback of overall force levels, and a system of strain gages is used to ascertain force levels transmitted by individual teeth. Multi-tooth dental bridges consisting of combinations of natural teeth and implants are the primary focus of the research. The objective is to determine the manner in which overall force levels are distributed during various chewing cycles. This information will be useful in understanding the manner in which potentially harmful levels of force are transmitted to human bone surrounding dental implants and adjacent teeth by providing more accurate force input data for finite element models which are under development. The use of a robotic system for generating motion and force transmission patterns will facilitate the standardization of procedures in evaluating implant designs.

How Occlusal Forces Change in Implant Patients: A Clinical Research Report

The author recorded the occlusion of 100 patients with fixed implant prostheses on 571 endosseous root form implants when the implants were placed. He made six subsequent occlusal contact comparisons at three-month intervals. Hyperocclusion occurred on implant prostheses in nearly half of the patients during the test period, with the majority of changes occurring in the first three to six months. These changes in the distribution of occlusal contact forces may partially explain the reports of early implant failure by other investigators, and they suggest the need for a more vigorous post-insertion occlusal evaluation.

Clinical evaluation of measuring system of occlusal force

An occlusal diagnostic system was evaluated for clinical applications. This system consists of pressure sensitive sheets (DENTAL PRESCALE, Fuji Photo Film Co.) and analyzing computer (OCCLUZER FPD703, Fuji Photo Film Co.). The clinical efficiency of this system was evaluated in aged dentates, aged complete denture wearers and an aged patient suffered from periodontitis. The results were as follows: 1. There was a positive correlation between the masticatory efficiency and maximum occlusal force. 2. In the complete denture wearers, the distances from the medial line to the center of the occlusal load were statistically greater in the adjustment needed cases than in the control group. 3. In a case of periodontitis, the full arch fixed splint was adjusted using this system. After adjustment, the maximum occlusal force and contact area increased, and the maximum and medial pressure of the occlusal contact force decreased. 4. It was suggested that this system would be available for the examination of masticatory efficiency and diagnosis of various types of occlusions.