Changes In Occlusal Vertical Dimension Research Articles

Increased Occlusal Vertical Dimension and Its Influence on Lip Position at Smile in Dentulous Adults

Introduction: Increasing occlusal vertical dimension (OVD) is often indicated in complex prosthodontic rehabilitations to gain restorative space and improve the occlusal relationship and esthetics. However, any alterations made in OVD will also influence the lip position mainly during rest and smile. This study aims to determine the influence of the vertical dimension of occlusion on lip positions at a smile. Methods: 30 samples between the age group of 20 - 30 years were included in this study meeting the selection criteria. The acrylic splint of varying thicknesses of +2mm, +4mm, +6mm, +8mm was prepared on the dental stone cast of a patient that was articulated in a semi-adjustable articulator after tentative facebow transfer. Smile photograph of each individual at the occlusal vertical dimension of +0mm, +2mm, +4mm, +6mm, +8mm was taken using a DSLR camera mounted on a tripod using the prepared acrylic splints. Digital measurements were done in photographs using the Adobe Photoshop software. Results: The study's results demonstrate that increasing the OVD significantly affects the inter labial distance, incisal edge to lower lip distance, and the display zone area. However, the study found no notable alterations in the distance from the incisal edge to the upper lip or in the intercommissural width with the same increased OVD. These findings demonstrate on how changes in OVD can influence various orofacial measurements. Conclusion: Within the limitation of this study, it can be concluded that with the increase in the OVD, inter labial distance, incisal edge to lower lip distance, and display zone area are increased. But upper lip position and inter commissural width should not be expected to be changed with increased OVD.

Assessment of Occlusal Vertical Dimension Change in Mechanical and Virtual Articulation: A Pilot Study.

The aim of this clinical study was to investigate the change in occlusal vertical dimension (OVD) with dental casts mounted on a mechanical articulator using an average axis facebow and on a virtual articulator mounted using the Bonwill triangle and the Balkwill angle and compare these groups with OVD change observed clinically in patients. Casts were obtained from each patient (n = 14) and mounted on a semi-adjustable articulator in the facebow preservation group (FPG) and on a virtual articulator using average anatomic values in the average mounting group (AMG). Customized mandibular anterior splints were virtually designed at an OVD increased by 3, 6, and 9 mm. Digital buccal scans were performed with the anterior devices in the participants' mouths in the intraoral group (IOG), AMG, and FPG at the different OVD increases accordingly. While no statistically significant differences (p > 0.05) were observed in the posterior interocclusal measurements with the incisal guide pin raised by 3 mm and 6 mm among all groups, a 9 mm increase resulted in a significant difference between AMG and IOG. The interocclusal posterior-to-anterior opening ratio observed clinically was 1:1.575. Increases in OVD up to 6 mm on dental casts mounted using average anatomic values performed similarly to the actual intraoral changes.

Assessing the change in occlusal vertical dimension in complete dentures prosthesis after processing: A cephalometric study

Introduction: Recording of jaw relations is the most important step in complete denture fabrication. One of the main reasons for complete denture failure is the error, in recording the correct vertical dimension of occlusion and its reproduction in final prosthesis. Methods: Thirty completely edentulous participants were selected for the study. The physiologic rest position of the mandible was used to record the vertical dimension of occlusion, and denture was fabricated following all the steps meticulously for all the study participants. A lateral cephalograph for each patient was shooted twice one with adjusted wax rims at determined the vertical dimension and another at denture insertion appointment. The comparative evaluation of both the cephalographs for the change in the angle made by two projection lines drawn by joining the orientation landmarks was carried out using the software of all the participants. Data were statistically analyzed using the Student's paired t-test, and software used in the analysis was the SPSS software version 22.0. Results: Statistically significant difference was observed in the mean occlusal vertical dimension (OVD) recorded at the Jaw relation stage with OVD in processed complete denture (t = 5.84, P = 0.000). Conclusion: The OVD recorded using the physiologic rest position method was found to be increased in the finished complete denture.

Comparative laboratory evaluation of dimensional accuracy for 3D-printed complete maxillary denture

Purpose: The objective of the research was to investigate dimensional accuracy concerning denture teeth deviation and vertical dimensional changes for three-dimensional printed, monolithic dentures relative to heat-cured, acrylic resin dentures. Materials and methods: A waxed-up reference maxillary denture was constructed on an educational master cast, and then duplicated to produce ten simulated waxed-up dentures. The planned virtual denture was designed by subtracting the scanned cast from the scanned waxed-up denture with the cast. This virtual denture was considered as a reference and saved alone in 3D- Standard Tessellation Language (STL) format. From this reference (CAD maxillary denture) ten DLP dentures were fabricated. Each fabricated heat-cured, and 3D-printed denture was scanned separately, and the scanned data was saved in an STL file. Each STL file of scanned maxillary dentures was superimposed on a reference virtual maxillary denture to evaluate the degree of denture teeth deviation. An electronic digital caliper was used to measure the occlusal vertical dimension (OVD) of the waxed-up denture and after denture fabrication for both groups to evaluate the change in OVD. Results: A paired t-test was used to compare the recorded data between both groups. It was reported that the higher mean values for either denture teeth deviation or vertical dimensional changes after dentures fabrication were noticed in heat-cured acrylic resin dentures. These values were highly statistically significant between the tested groups for both items of investigations at p ≤ 0.01.

EMG evaluation of masseter muscle during maximum clenching in complete denture wearers after reducing the occlusal vertical dimension

The rehabilitation of masticatory function, which made by natural teeth, one of the most goals of the treatment of complete dentures patients, Studies indicate that the change in occlusal vertical dimension (OVD) affects the patient's biting force. Purpose: This study aimed to evaluate the Electromyography (EMG) of masseter muscle during maximum clenching after reducing the OVD in complete dentures wears.Materials and Methods: Seven completely edentulous subjects, 2females and 5 males, their ages were between (45 -70) years precipitated in this study. One upper and two lower complete dentures were fabricated for each subject, the first set of upper and lower complete dentures was made with an appropriate OVD, while the second set of complete dentures were made with reduced OVD (about 3 mm). The EMG of the master, in both sides during maximum tooth clenching were performed two months after the patient delivered the first complete denture. The same procedures were repeated for the second set of complete denture wears after two weeks.Results: The mean value of the EMG of master muscle during maximum clenching for complete denture wearers with an appropriate OVD was (435.35) uV, while for the patients, who wear complete dentures with reduced OVD was (299.25) uV.Conclusions: There are statistically significant differences in the mean value of the EMG between the two groups at the confidence level of 95%. The value of the EMG in dentures with reduced OVD was smaller than that of appropriate OVD in the research sample.

Temporal changes in occlusal vertical dimension after bite-raising in bite-reducing model animals

Temporal changes in occlusal vertical dimension after bite-raising in bite-reducing model animals

Certain experiences in sequential treatment of occlusal reconstruction

Occlusal reconstruction is a complex sequential treatment. The treatment may involve changes in occlusal vertical dimension and the full dental arch occlusal surface reconstruction. In this paper, we discussed the most concerned aspects of prosthodontists during the occlusal reconstruction sequential treatment, how to determine the suitable occlusal vertical dimension, rebuilding of occlusal plane, and consideratiom of temporomandibular joint disorders during reconstruction treatment. The prosthodontists should adopt the multidisciplinary collaboration mode of thinking in analysis, design, treatment, and restoration processes, regarding patients' individual characteristic through the occlusal reconstruction sequential treatment, and to reach healthy, functional, aesthetic outcome eventually.

Effect of occlusal vertical dimension on swallowing patterns and perioral electromyographic activity.

Abnormal swallow patterns have been associated with specific dentofacial traits, such as an anterior open bite, but the cause-effect relationship between swallowing and malocclusion remains highly controversial. The aim of this research was to determine the effects of acute change in occlusal vertical dimension (OVD) on intraoral pressure swallow patterns and perioral electromyographic activity (EMG) during swallowing. Ten volunteers (five female, five male; 27-32 years) repeated standardised swallowing tasks as the OVD was progressively increased using mandibular trays of different heights. Standardised swallowing tasks were performed repetitively with each tray in place. Individual swallowing waveforms were quantitatively and qualitatively analysed. Peak pressure, swallow duration, time to peak pressure and lip EMG peak activity were assessed for each swallow. Data were analysed using mixed-model analysis. As OVD increased, lip peak pressure during swallowing increased almost threefold (+2·1 kPa; P ≤ 0·001), whereas swallow duration increased by 12·7 per cent (+160 ms; P = 0·01) at lip level and by 26·4 per cent (+270 ms; P < 0·001) at tongue level. Perioral muscle activity during swallows increased by 43·7 per cent (P ≤ 0·01) up to the OVD where resting lip seal was not attainable. Swallowing waveforms varied markedly between individuals, but interindividual waveforms were only minimally affected. The adaptive response and the waveform similarities associated with OVD variation supports the existence of a central control mechanism for swallowing, which may be modified by peripheral inputs.

Does altering the occlusal vertical dimension produce temporomandibular disorders? A literature review.

The purpose of this review was to present a comprehensive review of the scientific evidence available in the literature regarding the effect of altering the occlusal vertical dimens-ion (OVD) onproducing temporomandibular disorders. Theauthors conducted a PubMed search with thefollowing search terms 'temporoman-dibular disorders', 'occlusal vertical dimension', 'stomatognatic system', 'masticatory muscles' and 'skeletal muscle'. Bibliographies of all retrieved articles were consulted for additional publications. Hand-searched publications from 1938 were included. The literature review revealed a lack of well-designed studies. Traditional beliefs have been based on case reports and anecdotal opinions rather than on well-controlled clinical trials. The available evidence is weak and seems to indicate that the stomatognathic system has the ability to adapt rapidly to moderate changes in occlusal vertical dimension (OVD). Nevertheless, it should be taken into consideration that in some patients mild transient symptoms may occur, but they are most often self-limiting and without major consequence. In conclusion, there is no indication that permanent alteration in the OVD will produce long-lasting TMD symptoms. However, additional studies are needed.

Efecto del aumento de la dimensión vertical oclusal en la posición natural de cabeza en pacientes portadores de prótesis removible

ObjectiveTo determine the variation in the natural head positionon increasing the Occlusal Vertical Dimension (OVD) in patients who use removable dentures. Patients and methodsAn analytical, quasi-experimental study was conducted on 56 elderly patients volunteers, carriers of removal full and partial (only with group V remaining) dentures seen in the Odontology Faculty of the University of Chile in 2011. An analysis was made of the head position in a sagittal direction to change the OVD, gradually increasing the occlusal height by 5, 10 and 15 millimeters, using standardized profile photographs of the natural head position. Hypothesis: The increase in the OVD is associated with a posterior rotation of the head. ResultsAll the volunteers showed a change in the natural head position, posteriorly rotated to change the OVD. The ANOVA test showed that this change was not statistically different. There was a positive association between a gradual change in OVD and the degree of head rotation. The Pearson test showed a statistical association. ConclusionIt could be concluded from the results that, the greater the increase in occlusal height, the greater is the posterior rotation of the head. The findings of this study support the concept that there is an anatomical integration between the different elements that make up the cranio-cervico-mandibular unit, acting together against the variation of one of its components.

Influence of high expansion dental stone used as investing medium on the changes in occlusal vertical dimension of complete dentures

Despite advances in materials and techniques, complete dentures made of acrylic resin experience an increase in the occlusal vertical dimension (OVD) during processing. Many factors that affect the OVD of complete dentures are known. However, no study has examined the effect of using high-expansion dental stone (type V) as an investing material on the OVD. This study investigated the effects of using a high-expansion dental stone as an investing material on changes in the OVD of complete dentures. Twenty sets of simulated upper and lower dentures were processed by the compression molding technique. Specimens were equally divided into 2 groups. In the dental stone type III (DST III) group, the lower, middle, and upper parts of a flask were filled with DST III. In the dental stone type V (DST V) group, the procedure was the same as in the DST III group, except that the middle layer was made of high-expansion DST V. Changes in the OVD were measured before and after denture processing. Collected data were analyzed with t-test statistics. Differences were considered statistically significant at the 95% confidence level. Both groups showed a small increase in the OVD as a result of processing, but the OVD increase was significantly less in the DST V group compared to the DST III group. High-expansion DST V can be recommended as an investing material to reduce the increase in the OVD that may occur while processing complete dentures.

Alteration of masticatory muscle EMG activities during chewing after a reversible bite-raising in guinea pigs

Previous studies have investigated the effects of increasing the occlusal vertical dimension (OVD) with an oral appliance on masticatory muscle EMG activity during oral behaviours in humans and animals. The present study investigated whether a short-term and reversible increase in OVD, followed by a reduction in OVD to the normal level, resulted in a time-correlated change in the EMG activities of the masseter and digastric muscles during chewing. To do this, a guinea pig model in which an increased OVD was established with natural tooth contacts was used. In the control group, in which no bite-raising treatment was applied, OVD gradually increased with a natural growth during the experimental period whilst the masseter and digastric EMG activities, burst duration, and chewing rhythm were unchanged. When the increase in OVD was established in the bite-raised group, the EMG activities of the masseter and digastric muscles were significantly increased by 88.6 and 55.2% from those before bite-raising treatment, respectively. However, during the following 11 days, the increased EMG activities of both muscles did not show changes associated with the subsequent decrease in the OVD to a normal level. The burst durations of both muscles and chewing rhythm were not significantly affected by the change in OVD during the experimental period. Within the limited recording period of the study, the return of OVD from increased to normal levels did not reverse the increased chewing-related masticatory muscle EMG activity that was induced by the bite-raising treatment.

A comparative study of changes in vertical dimension of occlusion using four different investing methods

Statement of problem Acrylic resin complete dentures undergo dimensional changes during polymerization. Alternation in type of investment mediums and laboratory procedures can affect vertical dimension of occlusion. Purpose The purpose of this study was to compare changes in vertical dimension of occlusion of simulated complete dentures using four different investing methods in compression molding technique. Materials and Methods Four test groups with 10 sets of complete dentures each were evaluated. Flasking were done in four groups: Group 1: PlasterMixed, Group 2: PlasterStoneMixed, Group 3: PlasterMixedStone, Group 4: PlasterStonePlaster. All experimental groups were compression molded with denture base resin. Changes in occlusal vertical dimension were measured before and after denture processing. Collected data were analyzed with analysis of variance and Tukey's test at 95% level of confidence (p=0.05). Results The Mean of VDO changes in different groups were: group 1 (0.860 ± 0.839), group 2 (0.710 ± 0.585), group 3 (1.548 ± 0.951) and group 4 (0.578 ± 0.686). Conclusion There was significant difference between all tested groups. Less dimensional change was observed in the simulated dentures tested when they were invested with PlasterStonePlaster than when flasked with other investing techniques.

Role of Occlusal Vertical Dimension in Spindle Function

Several studies have suggested the jaw-muscle spindle as the receptor responsible for regulating and maintaining the occlusal vertical dimension (OVD). However, to challenge this assumption, we hypothesized that long-term changes in OVD could affect the sensory inputs from jaw-muscle spindles. In this study, we investigated changes in masseter muscle spindle function under an increased OVD (iOVD) condition. Responses of primary and secondary endings of masseter muscle spindles to cyclic sinusoidal stretches were investigated. Twenty barbiturate-anesthetized female Wistar rats were divided into control and iOVD groups. Rats in the iOVD group received a 2.0-mm composite resin build-up to the maxillary molars. After iOVD, masseter muscle spindle sensitivity gradually decreased. Primary and secondary spindle endings were affected differently. We conclude that iOVD caused reduction in masseter muscle spindle sensitivity. This result suggests that peripheral sensory plasticity may occur following changes in OVD. Such changes may provide a basis for physiological adaptation to clinical occlusal adjustments.

Novel Device for Measuring Vertical Maxillomandibular Registration

Purpose : This article introduces the use of a measurement device that was recently developed.Materials and Methods : This device was designed so that it can estimate changes in occlusal vertical dimension more precisely to measure the distance between the subnasal and the gnathion. It has several indicators and two scales. When positioned correctly, this device can measure, for example, the distance between the subnasal and gnathion on a patient or the distance of the interalveolar crest of the ridge of dentures. The authors performed an experiment using this measuring device to determine vertical dimension. Resin plates were used to raise the bite in a patient's mouth. The changes in the jaw position were measured by 11 clinicians using the device, and the measurements were statistically analyzed.Results : The results of the experiment confirmed that the device is stable. There was no correlation between the number of clinical years of experience of the clinicians and the distance measured from the subnasal to the gnathion of the subject.Conclusion : Stable measurements can be achieved with this measurement device.

Influence of Changes in Occlusal Vertical Dimension on Tongue Pressure to Palate during Swallowing

Purpose : The purpose of the present study was to examine the relationship of tongue pressure and changes in occlusal vertical dimension to swallowing.Materials and Methods : The volunteer subjects were four young male dentulous adults and eight elderly complete denture wearers. The tongue pressure to the palate was simultaneously recorded with electromyography (EMG) measurements of the suprahyoid muscles as the occlusal vertical dimension changed. The subjects were instructed to perform two actions : swallowing without any liquid or food (dry swallowing) and swallowing of 2 ml water (wet swallowing).Results : During dry swallowing, the maximum pressure decreased significantly as the vertical dimension increased in the young subjects. In the elderly, the maximum tongue pressure decreased monotonically as the vertical occlusion increased. The same results were clearly found for wet swallowing. Overall data suggested that the tongue pressure of the elderly group was lower and the duration of tongue pressure in wet swallowing was longer than that of the younger group.Conclusion : An increase of the vertical dimension decreased the tongue pressure to the palate, whereas a decrease of the vertical dimension affected the tongue pressure less. Tongue pressure is an important factor for the evaluation of tongue function, especially swallowing.

発語時下顎運動に咬合高径の変化が及ぼす影響に関する研究

発語時下顎運動に咬合高径の変化が及ぼす影響に関する研究

Removable magnetic dental attachment that permits magnetic resonance imaging

Magnetic dental attachments cause magnetic resonance image (MRI) degradation. A new magnetic dental attachment that allows removal of magnetic parts to exchange them for nonmagnetic parts was developed and tested. It allows high quality MRI with no change in occlusal vertical dimension. A volunteer test subject with combinations of attachments in place was examined by MRI. The images produced showed no degradation or distortion. Magnetic attachments for overdentures or maxillofacial prostheses should be removable to permit use of MRI.

こう合高径の変化がそしゃく運動に及ぼす影響 第１報 そしゃくリズムについて

Assessment of occlusal vertical dimension (OVD) is an essential in the dental treatment. However, physiolosical effects of the change in OVD remains unclear.The purpose of this study is to assess the effect of the change in OVD on the stomatognathic function by analyzing any chewing movements.Five subjects without any signs or symptoms of craniomandibular disorders and with normal occlusion (age: 24-28 years, 4 males and 1 female) were selected. Onlay-type appliance was fabricated to raise the OVD by about 2mm. The chewing movements were recorded and analyzed using the Sirognathograph Analyzing System III.As a result, no change was observed in cycle time of the chewing movements, however as for each duration, some changes was observed.

Relationship of occlusal vertical dimension to the health of the masticatory system

Changes in occlusal vertical dimension have been claimed to cause masticatory system disorders. Early articles on this subject were mainly limited to clinical case reports, and the more recent clinical studies have been flawed by the lack of control groups, blind evaluation, and by poor definition of criteria for evaluating the health of the masticatory system. Research with humans and animals has shown that if increases in occlusal vertical dimension are not extreme and the appliance used covers most of the dentition, there is a good possibility of adaptation. Current scientific knowledge does not support the hypothesis that moderate changes in occlusal vertical dimension are detrimental to the masticatory system.