Occlusal Force Distribution Research Articles

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.

Longitudinal study on occlusal force distribution in lower distal‐extension removable partial dentures with conus crown telescopic system

The purpose of this study was to examine longitudinal changes of the occlusal force distribution in lower distal-extension removable partial dentures with the conus crown telescopic system. Occlusal force applied to the denture and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 3 months after. The occlusal force distribution ratio to the retainers was calculated when a load of 20 N was applied to the denture. The results are summarized as follows: (i) The more posterior the loading point of occlusal force, the smaller was the ratio. When the occlusal force was applied to the most anterior artificial tooth, the ratio was 65-100% of the occlusal force. (ii) As the denture wearing time proceeded, the ratio was decreased. The smaller the ratio, the greater was the rate of its decrease.

Longitudinal study on occlusal force distribution in lower distal-extension removable partial dentures with circumferential clasps.

In this study, longitudinal changes of the occlusal force distribution ratio were examined in lower distal extension removable partial dentures with cast circumferential clasps. Occlusal force applied to the denture base and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 4 months after. Two rates of loading were chosen. One was simulated mastication (fast loading rate) and the other was 10 Ns-1 (slow loading rate). Location of the loading points were first premolar (P1), second premolar (P2) and first molar (P3) of the denture. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the loading point. The results are summarized as follows: (1) The occlusal force distribution ratio at fast loading rate on P1 and P2 was changed until 1 or 1 1/2 months after the insertion of the new dentures, and then became constant. This constant value was 30% on P1, 20% on P2 and 10% on P3. (2) Slow loading rate produced a greater ratio than the fast loading rate on P2 and P3 while there were no remarkable differences in the ratio between both loading rates on P1.

義歯軟質弾性裏装材による裏装効果 こう合力分布に関する臨床的検討ならびに模型実験による考察

義歯軟質弾性裏装材による裏装効果 こう合力分布に関する臨床的検討ならびに模型実験による考察

有床義歯装着者の骨吸収のシミュレーション 第２報 上顎におけるリベース，リライン，付与するこう合および義歯の強度の影響

Occlusal force distribution is considered to be one of the major factors for bone resorption underneath denture base. We developed the program for simulating this process utilizing a two dimensional finite element model and an optimization program. In this report, influence of rigidity of denture base, loading condition, rebase and reline and on bone resorption were examined and following results were obtained.1. Rigidity of the denture structure had much influence on bone resorption. Denture base with high rigidity caused less resorption compared to the one with low rigidity.2. Area and amount of bone resorption were closely related to the loading location and direction. Least amount of resorption was found when the load applied vertically at the palatal side.3. Rebase and reline procedure without altering occlusion could result in further resorption.

Occlusal force distribution in lower complete overdentures

A space between the denture base and a root cap can effectively control the distribution ratio of occlusal force to abutment teeth and an alveolar ridge. The purpose of this study on abutments was to analyse the effect of variation in space (0 mm (no space), 0.3 mm and 0.6 mm) on the above ratio. Six subjects, 38-65 years of age, each with an edentulous maxilla and several teeth remaining in the mandible, were selected for this experiment. The lower experimental denture had embedded a transducer which could detect a change in the vertical force applied to the experimental tooth. This transducer was capable of changing the vertical space between a denture base and an experimental tooth. Each subject was asked to increase the occlusal force applied to the denture from zero to the maximum loading rate of 5 kgf s-1. The occlusal force and the force exerted on the experimental tooth were recorded in each space 1 month after insertion of new dentures. The following results were obtained: (i) when the occlusal force was applied to the artificial tooth just above the abutment tooth, the mean ratio in the 0 mm space was 60% of the force applied to the denture, the ratio in the 0.3 mm space was 50%, and the ratio in the 0.6 mm space was 30%; (ii) if the occlusal force was applied to the point 10 mm distant from the point just above the experimental tooth, the magnitude of the ratio was decreased by 60-80%.

Distribution of occlusal forces along unilateral posterior two-unit cantilever segments in cross-arch fixed partial dentures

Axially directed occlusal forces over unilateral posterior two-unit cantilever segments of cross-arch fixed partial dentures were measured during natural functioning by using built-in transducers, one in each cantilever unit. The mean local maximal occluding and maximal chewing forces were significantly larger over the first (124 N and 64 N) than over the second (21 N and 29 N) cantilever unit. The average intraindividual ratio between the forces over the first and second cantilever unit amounted to 12:1 for maximal occlusion and 3:1 for maximal chewing. Despite the smaller mean total maximal chewing (92 N) than mean total maximal occluding cantilever force (145 N), the resulting axially directed mean bending moments in the joint between the distal abutment crown and the cantilever segment did not differ significantly. This is explained by the larger mean maximal chewing (29 N) than mean maximal occluding (21 N) force over the second cantilever unit. This demonstrated that not only the magnitude of occluding and chewing forces over cantilever segments but also their distribution along the cantilevers is of importance for the magnitude of functional stress created in cantilever fixed prosthesis.

Prevention of acquired immunodeficiency syndrome and hepatitis B. II: Disinfection method for hydrophilic impression materials

11. Lyon HE. Resin-bonded etched-metal rest seats. J PROSWET DENT 198$53:366-B. Janus CE, Schufeldt HA, Beck DA, McCasland JP, Eshelman JR. The use of custom cast-metal resin-bonded cingulum rest seats under removable partial dentures. Compend Contin Educ Dent 1985;6:364-8. Barrack G. Etched cast restorations. Quintessence Int 1985; 16~27-34. Livaditis GJ, Thompson VP. Etched casting: An improved retentive mechanism for resin-bonded retainers. J PROSTHET DENT 1982;47:52-8. ,Wong R, Nicholls JI, Smith DE. Evaluation of prefabricated cingulum rest seats for removable partial dentures. J PROSTHET DENT 1982;48:521-6. Maxfield JB, Nicholls JI, Smith DE. The measurements of forces transmitted to abutment teeth of removable partial dentures. J PROSTHET DENT 1979;41:134-42. Meiers JC, Meeta HK. Design modifications for etched-metal, resin-bonded retainers. Gen Dent 1985;33:41-4. Seto BG, Caputo AA. Photoelastic analysis of stresses in resinbonded cingulum rest seats. J PROSTHET DENT 1986;56:460-5. 12. Yurkstas A, Curby WA. Force analysis of prosthetic appliances during function. J PROSTHET DENT 1953;3:82-7. 13. Ogata K, Maeda Y, Nishigawa G, Okuno Y. Occlusal force distribution in removable partial dentures: A preliminary report. J Osaka Univ Dent School 1983;23:187-94. 14. Williams VD, Svare CW. The effect of five-year storage prior to bonding on enamel/composite bond strength. J Dent Res 1985;64;151-4. 15. Toth RW, Fiebiger GE, Mackert JR, King GE, Goldman BM. Load cycling of lingual rest seats prepared in bonded composite. J PROSTHET DENT 1986;56:239-42. 16. Prevost AP, Fuller JL, Peterson LC. The use of an intermediate resin in the acid-etch procedure: retentive strength, microleakage, and failure mode analysis. J Dent Res 1982;61:412-8.

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について ＩＶ 維持歯の負担率

The purpose of this study was to investigate, longitudinally, the ratio of occlusal force distribution between abutment tooth and alveolar ridge in removable partial denture patients.The subjects in this study were 5 females with a maxillary complete denture and a mandibular complete overdenture.The occlusal force acting on the artificial teeth was measured with the occlusal force transducer and the vertical force exerted on the abutment tooth was measured by the specially designed transducer installed in the denture base. They were simultaneously recorded and the ratio between them (V/O ratio) were determined.A half month after the insertion of dentures in three subjects, the V/O ratio decreased. In the other subjects, it remained constant. After this initial period, the ratio stayed constant in every subject and the value of the ratio was determined to be 0.1-0.4 when the transducer made direct contact with the abutment tooth. In the case when a space existed between the transducer and the abutment tooth, the value was determined to be less than 0.1.

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について ＩＩ Ｃｏｍｐｌｅｔｅ ｏｖｅｒｄｅｎｔｕｒｅ装着者で義歯床と被験歯との間にスペースを持たせなかった場合

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について ＩＩ Ｃｏｍｐｌｅｔｅ ｏｖｅｒｄｅｎｔｕｒｅ装着者で義歯床と被験歯との間にスペースを持たせなかった場合

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について ＩＩＩ 緩圧の効果

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について ＩＩＩ 緩圧の効果

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について Ｉ 測定方法について

有床義歯装着者の歯および粘膜へのこう合力の負担配分に関する経時的変化について Ｉ 測定方法について

Photoelastic stress analysis of overdenture attachments

This is a summary of various investigations designed to study the transmission of forces through overdenture abutments to the remaining oral structures: 1. The best design for uniform distribution of occlusal forces to the remaining structures was the conventional design, particularly the amalgam restored abutment. This design, however, provided less effective retention and stability than the other designs. 2. In the group of stud type attachments studied, the Ancrofix transferred stress in a more favorable manner to the remaining structures in the oral cavity when compared to the other stud attachments. 3. The Hader Bar provided more desirable effects to the abutments and remaining structures than did the other tissue bars. 4. The major objective in the choice of an overdenture attachment should be the consideration of how the stress is transferred from these attachments through the abutments and other structures, not the retnetion and stability.

Load-transfer characteristics of mandibular subperiosteal implants

M andibular subperiosteal implant dentures have been used successfully for over 25 years in the treatment of edentulous, atrophied mandibles. Histologic studies of the human mandible have shown that a complete mandibular subperiosteal implant denture may be tolerated and the adjacent surrounding oral tissues maintained in a relatively healthy condition for 10, 15, and more years.le3 Mandibular subperiosteal implant denture substructures utilize the principle of cross-arch stabilization with a positive substructure seated on a large area of dense cortical mandibular bone for maximum distribution of masticatory forces (Fig. 1). Minimum bone injury is produced with denture function, which accounts for the favorable prognosis of a well-constructed subperiosteal implant complete denture.* Occasionally the dense cortical mandibular bone supporting a subperiosteal implant may slowly resorb over a period of years as a result of excessive forces of occlusion (Fig. 2). If a local region of bone receives too large a workload, resorption which could endanger the implant may take place. Bodine and Mohammed,‘-3 Bodine,4 and other investigators used a bar to connect the anterior and posterior posts of the conventional subperiosteal implant to improve the distribution of occlusal forces. The purpose of this investigation was to compare the load-transfer characteristics of the conventional subperiosteal implant designs with the occlusal connected bar design.

Clinical and Materials Sciences

A human mandible was duplicated in birefringent resin. The distribution and effect of occlusal forces within the mandible was demonstrated utilizing birefringent resin models compared to natural specimens. The results of this study reinforce those theories that assign function a major role in bone remodeling in the mandible. Further, the condyle is seen to be a stress-bearing structure.

On the hominid masticatory complex: Biomechanical and evolutionary perspectives

All too frequently evolutionary interpretations of the hominid fossil record are based on conclusions about the functioning of the oro-facial apparatus which seldom consider the interrelationships of the many variables of this complex anatomical region. This paper attempts to identify these variables and to apply them in an examination of the argument that worn occlusal surfaces of the dental arches represent a three-dimensional record of occlusal force distribution. It suggests that the pattern and extent of attritional contours should be a valuable tool for interpretation of the adaptive and survival value of the dentition of extinct hominids. In order to understand this force distribution over the dental arches a study must be made of the variables that govern the characteristics of the masticatory force system. Facial morphology and the masticatory musculature produce a particular load distribution for each chewing mode. The teeth upon which the resultant forces act give evidence of the force location and magnitude by the wear produced on the crown. Our studies have shown that occlusal loading patterns, cusp size and morphology, enamel thickness, dental eruption sequence, diet and masticatory manipulative behaviors interact to produce observed wear patterns. In reviewing the several recent reports which describe one or several of these factors in analysis of the hominid dental complex we have concluded that controlled experimental analysis will provide information on the interaction of those factors which produce dental wear. Such analysis should provide a necessary basis for evolutionary interpretation of the hominid dentition.

Stress Distribution of Occlusal Force to the Alveolar

Stress Distribution of Occlusal Force to the Alveolar

Essentials of a sound complete denture technique

A sound complete denture technique that is suitable for general practitioners has been described. It is practical as well as scientific, built on sound principles and with no weak links in the necessary chain of steps in the technique. The essential steps are: 1. Good impressions are made with accurate Usable functional borders. This is not a place to hurry or use shortcuts. Extra time and effort applied to making the impressions will be saved later in adjustments and will be repaid many times over in patient comfort. 2. Accurately fitting stabilized bases are used. No jaw relation record, no matter how accurately recorded, is ever any better than the base upon which it is made. 3. An accurate centric relation record is made with an equalized distribution of occlusal forces. Most dentists can do this best by using some type of central bearing needle-point tracing device. 4. The processed dentures are remounted in their original positions on the articulator for the correction of the occlusion before the dentures are removed from their casts. By this means, the accurate jaw relations so carefully recorded are incorporated into the finished dentures. 5. The patient is given conscientious, skillful, and adequate insertion and post-insertion denture adjustments, and sympathetic and psychologic encouragement until he has mastered the dentures. Prosthodontics is hard exacting work, but the result of sincere effort pays for itself many times over in patient satisfaction, and in personal pride and enjoyment in having done a difficult job to the best of ones' ability, thereby making life more pleasant for someone who has come to us in need of help.

An evaluation of incisal guidance and its influence in restorative dentistry

UNCTIONAL COORDINATION of the occluding surfaces of the teeth has been spoken of as one of the most important sciences in the practice of dentistry. The incisal guidance, which is normally the inclination of the lingual surfaces of the six upper anterior teeth, might be considered as the key to a harmonious functional relationship of the natural dentition, or the key to functional occlusion. It might clarify our thinking to outline some differences in our concept of the ideal functional relationship of teeth of the complete denture from that of the natural dentition. In complete dentures, the six upper and six lower anterior teeth seldom make contact in the centric maxillomandibular relation; this contact is not necessary for the most favorable distribution of stress over the maximum denture-bearing area. In the natural dentition, contact of the six upper and lower anterior teeth is most common and is essential for the most favorable distribution of occlusal forces over the maximum number of teeth. In complete dentures, the three point balancing contacts in all eccentric positions, lateral and protrusive, are essential for the maximum functional stability of the dentures and the most favorable distribution of stresses. In the natural dentition, balancing contacts, that is, contacts of the posterior teeth in the protrusive relation, or contact of teeth on the nonfunctioning side in the lateral eccentric relation, seem to be not only nonessential for the most favorable distribution of functional forces, but these balancing contacts are a common contributing cause for the loss of alveolar support about the posterior teeth or for pathology of the temporomandibular joint. It is so extremely difficult to differentiate the nondestructive balancing contacts of the natural dentition from the destructive ones that their elimination would seem to be a reasonable measure of prevention. They should always be eliminated in the treatment of periodontal disturbances of the teeth involved, or of a dysfunction of the temporomandibular joint.