The FE models in this study were based on those re- ported by Kasai et al. . The material properties of the soft tissues such as the PDL and the TMJ, which were mainly deformed in the analysis, were considered to be crucial, because the aim of this study was to investigate the distribution of occlusalforces on the teeth, implants, and TMJs. In Figs. 3 and 8, the PDLs of anterior teeth and the springs corresponding to opposing teeth show two- stage displaceability as reported previously [16, 17] and were considered to be appropriate. The load-displacement curve of the springs corresponding to TMJs was assumed to be similar to that of the cartilage  because of its far smaller elastic modulus than that of the TMJ disc [19, 20]. Therefore, the elastic modulus of the springs correspond- ing to TMJs was determined based on the thicknesses of the TMJ disc  and articular cartilage , the stress- strain curve of the intervertebral discs , and the dis- placement of the condyle [22, 23] in intercuspal clenching by indirect measurement. Although the material proper- ties of human body depend on the individual, the models in this study were therefore considered to be appropriate to investigate the distribution of occlusalforces on the teeth, implants, and TMJs.
Occlusal trauma has been defined as “A condition where injury results to the supporting structures of the teeth by the act of bringing the jaws into a closed position”. (Stillman 1917) Recently, the American Academy of Periodontology (2000) changed the definition to “injury to the periodontium may result from occlusalforces in excess of the reparative/adaptive capacity of the attachment apparatus.”
The T-Scan occlusion analysis system is a dental tool that is used to analyze masticatory force. It was first devised in 1984 to measure occlusalforces and contact times as a prosthodontic adjunct in the treatment of occlusal problems and temporomandibular disorders. It has also been used as a measurement guide during prosthetic insertion and occlu- sal adjustment procedures. Data on occlusalforces and con- tact times are gathered by a recording sensor in the T-Scan system, 9 and can subsequently be visualized in movie for-
Occlusal force has the main role in determining the teeth health in general and determining the chewing, muscle and TMJ function. The objective of this study was to find if there was any relation between the preferred chewing side and the force, measured by T-scan III system. The total num- ber of 90 (46 female and 44 male) dental students was included in this study. They were asked whether their preferred chewing side was right, left or both. Afterwards, the occlusalforces in ha- bitual occlusion, using T-Scan III Electronic device (IP-CO position mode, MA-mode, MA sensitivity setting) were measured. The data were presented as Mean ± SD. Spearman correlation was used to find the correlation between the occlusal force and chewing side. Differences in P < 0.05 were con- sidered significant. There were 90 subjects (46 female and 44 male) mean age 23.3 (SD ± 2.2 years) included in the study. The preferred chewing side of 42 subjects was the right side, 24 of them preferred the left side and the other 24 preferred both sides as the chewing side. Occlusal force was higher in the preferred chewing side (P < 0.05) but using Spearman correlation, there was no statistical significance of occlusal force between the groups, the left side (r = −0.143, P > 0.05) and the right side (r = 0.143, P > 0.05) according to the preferred chewing side. In this study, the rela- tion between the preferred chewing side and occlusal force was found.
Despite the conflicting evidence, two conclusions have been drawn . Precipitous bone loss from overloading has been shown in a few investigations, but the majority of the more recent animal studies has not replicated these findings. Total loss of osseointegration of an in- tegrated implant appears possible when the applied force exceeds the biological threshold, but this limit is currently unknown, and contingent on the bone quality and possibly the level of inflammation. While it is difficult to quantify the magnitude and direction of naturally occurring occlusalforces, a number of clinical studies may offer clues to appropriate implant/prosthetic treatment planning to minimize peri-implant disease and point to future research.
Objective: The aim of study is to evaluate premature contacts and occlusalforces for each tooth in complete dentures before occlusal adjustment. Ma- terial and methods: The study population was comprised of 30 subjects (aged 50 - 75). The measurements were performed using the T-Scan. The oc- clusion was analyzed before and after frames which from the T-scan “Force Movies” are Centric Relation bite recordings. Several practices closures were made until a repeatable pattern of contacts was seen on the video monitor and sensor was calibrated. Each subject was asked to bite on the sensor in a position of maximum intercuspation thus obtaining the location of each tooth contact. Premature contacts and percentage distribution of forces per tooth were obtained before and after occlusal adjustment. Results: The worst occlusal balance was recorded in a patient (F/74) by occlusal force values at right 5.9% and left 94.1% before occlusal adjustment. After occlusal adjust- ment, all patients’ percentage of occlusal balance values was adjusted at average of 48.8%, left 51.1%. The percentage distribution of forces per tooth results showed that premature contacts had been observed at posterior teeth either right or left side of occlusion. Conclusions: Occlusal adjustment is requested for all complete dentures to prevent patients from muscular pain and/or temporomandibular disorders for further terms.
relation may have been repositioned into the correct position coinciding with the centric relation by muscular force, that is the bite force. Under conditions in which an occlusal discrepancy exists until the tooth is reposi- tioned into the correct position, temporary clicking may be produced. However, if the bite force is small before the completion of the permanent dentition, the malposi- tion of the occlusion will be maintained. Once the per- manent dentition stage has been reached, usually at an age of 10-12 years, the muscles frequently adopt an occlusal position that does not coincide with the centric relation. This new position of occlusal contact usually begins as an expedient process to avoid interferences, providing better function than the centric relation pro- vides at that moment. The continued presence of the occlusal discrepancy causes the new reflex pattern of the pathway to be used so repeatedly that the new posi- tion of the mandible may resemble the centric relation. This acquired position can be regarded as the usual or habitual occlusal position . In the present study, subjects No. 31 and 46 had a significantly smaller bite force at the ages 8 and 9 years old, respectively (mixed dentition); thus, the occlusal discrepancy may have appeared as a result of the small bite force, and this dis- crepancy may have been maintained once the perma- nent dentition was achieved, resulting in the persistent clicking. Although no data on the occlusal force at the ages of 8 or 9 years were available for subjects No. 59 and 60, the occlusalforces of these two subjects tended to be smaller than those of the others at later stage (dif- ference not significant; see Table 6). Therefore, the Table 5 Unassisted maximum opening (mm) in subjects with and those without persistent TMJ clicking (continuing for more than two years)
One of the objectives of our study was to eval- uate the relationship between dynamic parameters of digital occlusion analysis and patients’ complaints and clinical symptoms. The results imply that irre- versible dislocation of the articular disk is less prev- alent than reversible, as the symptom of clicking was recorded in 22.7% of the patients. It may also be noted that pain in the temporomandibular joint coincides with functional imbalance of stomatog- nathic system, changes in the movements of the low- er mandible, and emerging muscular hypoactivity; therefore, the force of chewing and pressure decreas- es (30). Subsequently, occlusalforces distribute un- evenly on both dental arches during occlusion and an imbalance between distributions of forces on one side of the mandible with respect to the other side emerges. The study by overseas authors on the rela- tionship between TMDs and occlusion (4, 6, 16) has not considered patients’ complaints. Studies of this kind have not been found.
FEA is useful for mechanical simulations of a living body and has been used in implant dentistry research under careful consideration of the analysis conditions [32, 33]. Although some reports have demonstrated that bone density varies according to bone type and location, the material properties of the mandible were homogenous and isotropic in this study. However, the effect of this difference was considered to be negligible under the confirmation of the displacement of teeth and implants because of its far larger elastic modulus and far smaller strain than those of soft tissues, such as TMJs and PDL. Since the purpose of the present study was to examine the distribution of occlusalforces on the occlusal surface, occlusalforces should be mainly affected by the displaceability of TMJs and teeth, not by that of osseoin- tegrated implants.
Case presentation: A patient who is a 45-year-old woman, non-smoker and has no medical record of interest with a longitudinal fracture in the palatal root of molar tooth 1.7 and absence of tooth 1.6 was selected in order to receive a zirconia implant with a PEEK-based restoration and a composite coating. The following case report describes and analyses treatment with zirconia implants in molars following a flapless surgical technique. Zirconia implants are an alternative to titanium implants in patients with allergies or who are sensitive to metal alloys. However, one of the disadvantages that they have is their lack of elasticity, which increases with the use of ceramic or zirconia crowns. The consequences that can arise from this lack of elasticity have led to the search for new materials with better mechanical properties to cushion occlusal loads. PEEK-based restoration in implant prosthetics can compensate these occlusalforces, facilitating cushioning while chewing.
Okane H 30 . in 1979, conducted a study on 4 patients (3 men and 1 woman) wearing complete dentures of age between 61-79 years to study the effect of anteroposterior inclination of the occlusal plane on muscle activity during clenching, on biting force and to estimate physiologically the applicability of ala-tragus line. At three different antero-posterior inclinations of the occlusal plane, at a constant vertical dimension of occlusion, the integrated electromyographic activity and biting forces of the patients were studied. Three orientations were used- first plane parallel to ala- tragus line extending from inferior point of ala of nose to lower border of tragus and other two planes were 5 degrees anteriorly and 5 degrees posteriorly inclined to the first plane. It was observed that biting force and clenching was greatest when the occlusal plane was parallel to ala-tragus line and it decreased when the plane was inclined about 5 degrees anteriorly or 5 degrees posteriorly. The antero-posterior inclination of the plane of occlusion affects the biting force and the ala-tragus line seems to be the most reasonable for orientation of occlusal plane.
Force diagrams show you the direction a force is acting in. It shows you the direction an object is being pushed, pulled or twisted. The direction of the arrow shows you the direction of the force. The sizes of the arrows can be used to compare the sizes of the forces.
Using a small round sectional wire with a right angle bend in the initial stages of bracket engagement for uprighting, leveling, and rotating involves the risk of having the wire rotate on itself in the mouth. This may misdirect the forces, and/or injure the cheek or lips. The sectional can be made non- rolling with a modification in the ligature tie. A helix is made in the center of the ligature wire and it is slipped over the short vertical anterior end of the archwire. When the ligature is twisted at the distal of the bracket, the occlusal portion of the ligature is always snugly up the gingival portion of the ligature wire into the bracket. Small, round sectional wire with right angle bend stabilized with helix-modified ligature wire on the short, vertical anterior right angle bend. These ligatures are formed as lefts and rights, depending on which extension from the helix (mesial or distal) crosses underneath the top portion of the helix (Fig 12a). (Hitchcock, 1981) The ligature can also be adapted within the helix to stabilize the wire in the anterior segment (Fig 12b). This tie also prevents the round sectional wire from slipping forward or back in the horizontal plane. The wire is held in three planes of space. It can be used with square or rectangular sectionals; where a tieback towards the front of the mouth might be easier to accomplish, and more comfortable for the patient. (Hitchcock, 1981)
nics further illuminate our study’s findings. The anterior teeth or premolars guide jaw movement, and the pre- molars participate in the early stage of mastication, including moving the bolus of food towards the occlusal surface of the molars. The occlusal pressure from CI to PM2 was larger than that at M1 and M2, and so pros- theses at the anterior or premolar teeth, in particular the maxilla, would bear a larger lateral force and run a greater risk of damage. Therefore, extremely close atten- tion should be paid to the design of prostheses taking jaw position, movement, and parafunctional habits into con- sideration.
The design-l in dental terminology  is known as MOD (Mesial Occlusal Distal) which indicates that the cavity created start from mesial region and along the occlusal surface ranges up to the distal region. The modelling is done using the following procedure. The spline through key points is plotted by entering the three dimensional coordinates of the cavity. The straight line is used to convert spline into closed boundary area. The closed boundary area is extruded along normal direction. This procedure is used for solid cavity as a single entity. The solid cavity is subtracted from natural tooth volume by Boolean subtract command. Design-l of molar crown is as shown in Figure 2(a).
employed to measure changes in A point. The method developed by Pancherz utilizes a reference grid constructed from the occlusal line (OL) and the occlusal line perpendicular (OLp) 15 . Maxillary measurements using this method are subject to patient positioning errors. Many studies use SNA to examine maxillary changes 1, 14, 28 . However, increases in the vertical dimension as seen with growth will mask the anterior-posterior change when using these angular measurements 6 . Skeletal changes observed at A point, undeniably depend on the methodologies used. Our 3-D study showed the anticipated forward and downward growth pattern of the maxilla in the majority of our class II control subjects. However the Herbst group showed a mild maxillary restraining effect.
The purpose of the occlusal adjustment was to obtain occlusal stability in the BPOP. For the occlusal adjust- ment in the patient ’ s mouth, the anterior bite plate was worn in the mouth; the patient was then asked to tap and slide his or her anterior teeth against the plate for 5 minutes, while in an upright position. The plate was then removed, and the patient was asked to close his or her jaw until tooth contact was made and then to hold that position. Premature contact was located in the mouth by marking and pulling with an occlusal tape (Occlusion foil; Coltene/Whaledent Gmbh Co., Lan- genau, Germany), and the contact was then removed. The plate was worn again, and the same procedure was repeated until more occlusal contacts on the posterior teeth were obtained. One session of occlusal adjustment was completed within 30 minutes. After completing one session, impressions of both jaws and three BPOP wax records were taken to prepare for the next appointment. The casts were attached to the articulator, and the occlusion was examined using the casts before the next appointment. The occlusal adjustment was completed by confirming the occlusal contacts on the premolar and molar teeth on both sides of the casts attached to the articulator and in the mouth.
Occlusal splint therapy may be defined as “the art and science of establishing neuromuscular harmony in the masticatory system by creating a mechanical disadvantage for parafunctional forces with removable appliances” ( et al., 2001). Occlusal splint is a diagnostic, relaxing, repositioning and reversible device. According to Glossary of Prosthodontic Terms-8, occlusal splint is defined as “any removable artificial occlusal surface used for diagnosis or therapy affecting the relationship of the mandible to the maxilla.It may be used for occlusal stabilization, for treatment of temporomandibular disorders, or to prevent wear of the dentition.”A bite splint can be a valuable diagnostic an treatment aid in carefully selected cases if properly made, adjusted and maintained. A properly constructed splint supports a harmonious relation among the muscles of mastication, disk assemblies, joints, ligaments, bones, teeth, and tendons. It provides a relatively easy, inexpensive and non harmful way to make reversible changes in the occlusion (SangeetaYadav et al., 2011).
Discussion The tooth morphology is slightly variable within different species of this genus, although the heterodonty pattern appears to be the same in all the species where a sufficient amount of teeth have been found. Although both L. africanus and L. cassangensis are known from articulated specimens with relatively well-preserved skeletal remains, it is unclear if the two species are synonymous (Antunes et al., 1990), both being from the Early Triassic of southern Africa. Teeth of L. angulatus, another Scythian species, have a weakly developed lingual protuberance and this makes the teeth slightly ‘diamond-shaped’ in occlusal view. The heterodonty pattern of L. cristatus is not clear but there are both typically higher anterior teeth and lower laterals in the collection of teeth upon which this species is based. Both L. nodosus and L. minimus are species well known from at least several hundred teeth and their heterodonty patterns are well recognised (see Duffin, 1985: text-fig. 12). As in most Lissodus species, they have higher, cuspidate anteriors and lower laterals with a less pronounced labial protuberance. These two species appear to be the first within the genus to develop enlarged lateral teeth. The same general morphology can be found in the roughly contemporary L. lepagei, although teeth of this species have a crenulate occlusal crest and more pronounced cusplets. Anterior teeth of L. hasleensis are less expanded and the lateral teeth are not as enlarged as in L. minimus and L. nodosus, but are otherwise similar. Three nominal species of Lissodus (L. leiodus, L. leiopleurus and L. wardi) are recorded in the British Bathonian. The status of all three is in need of revision as they are based on fairly small collections of teeth. Teeth of L. wardi are very similar to those of L. leiodus (Duffin, 1985) and the former may constitute a junior synonym of the latter, L. wardi possibly representing smaller anterior and juvenile teeth collected by bulk sampling. Lissodus leiopleurus appears to be a true species, the teeth possessing a higher crown and more developed vertical folds. It also appears to have a rather different distribution to L. leiodus, being especially common in non-marine sediments of the Hebridean Basin, Scotland (CJU, pers. obs.). The stratigraphically youngest species, L. levis, has low teeth without a well-developed cusp or cusplets in lateral teeth. The general morphology corresponds well to that of other Lissodus species.
Six observers viewed all the images from both the modalities. These observers were two radiologists, two radiology residents and two general dentists. They were asked to record the presence or absence of occlusal caries on a 5 point confidence scale which ranged from 1 = caries definitely absent to 5 = caries definitely present(Table 5). The observers were given a short training session in using Sidexis software and also provided with an instruction brochure on how to observe the images. The intraoral images were viewed using Vixwin 2000 (version 1.11, Gendex) and the cone beam images were viewed using Galaxis software (Sirona, Germany). To standardize the viewing conditions all the images from both modalities were viewed using one computer (Lenovo, Think vision, IBM, USA) in the Radiology clinic under dimmed lighting.