Physiologic Rest Position Research Articles

3D Facial Changes Between Maximal Intercuspal Position and Physiologic Rest Position.

To evaluate the soft tissue changes of the face between two positions of occlusion: maximal intercuspal position (MIP) and physiologic rest position (RP). In this study, facial surface scans of 83 volunteers in two mandibular positions (MIP and RP) were obtained using a 3D optical scanner. On each 3D image, 21 cephalometric soft tissue landmarks were identified and then compared using t test for various facial parameters (widths, heights, depths, angles, and ratio). Additionally, a regional analysis of the facial surface differences in each patient between the two mandibular positions was performed using a whole scan shell best-fit method and the regional forehead best-fit method. In MIP, facial heights with the nasion-gnathion distance shortened by approximately 1.2 mm (due to the vertical shrinkage of both lips together by 0.8 mm), and the mouth width was significantly widened, while other facial widths displayed no change. The labiomental angle and the upper vermilion arch were altered correspondingly, and regional analysis confirmed the findings with evident changes in the mandibular and subnasal areas with deviations amplified toward the facial midline. By applying 3D facial-scanning technology, this study displayed changes of facial appearance in different mandibular positions (MIP and RP), highlighting the need to instruct and monitor the patient's mandibular position more consistently to achieve accurate and repeatable data in a 3D facial analysis.

An Anthropometric Association of Vertical Dimension of Occlusion with that of Ear, Nose, Little Finger and Rima Oris in Dentate Individuals for Evaluation of Vertical Dimension of Occlusion in Edentulous Patients - An Observational Study

Background: Successful clinical performance of implant supported prosthesis and complete denture usually depends upon the correct establishment of occlusal vertical dimension during their fabrication. Aesthetic, functional efficiency and rigidity of masticatory muscles are the adverse effects of inaccurate vertical dimension. No reliable parameters are present for the determination of the same, thus posing a significant challenge to the clinicians. Numerous post-extraction methods like facial esthetic appearance, physiological rest position, cephalometric analysis, deglutition, measurement of former dentures, and various anthropometric analyses have been recommended. Aim: Thus, the main of the study was to evaluate the correlation of vertical dimension of occlusion with the length of nose, ear, little finger and the distance between rima-oris in dentate Kashmiri population, in order to use this correlation to determine vertical dimension of occlusion in edentulous patients. Material and methodology: 200 dentate volunteers of 25-45 years of age who fulfilled the inclusion criteria were selected for the study. The anthropometric measurements of vertical dimension at occlusion, length of ear, nose, little finger and the distance between rima-oris were measured using a vernier caliper. Unpaired t test was done to compare continuous variable, while Pearson correlation coefficient was calculated to measure the correlation among the anthropometric measurements. Linear regression equation was used to derive vertical dimension at occlusion with the nearest parameter and a p-value of less than 0.05was significant. Results: On evaluation, the length of nose in females and length of ear in males had a strong correlation with that of vertical dimension at occlusion. Conclusion: within the limitations of the study, it was concluded that length of nose in females and length of ears in males can be used as an adjunct for the establishment of vertical dimension at occlusion in edentulous patients. Keywords: Ear, Edentulous Patients, Nose, Little Finger, Rima-Oris, Vernier Caliper.

Concept of rest position of mandible: An overview

Physiologic rest position of the mandible is an important parameter to be considered in the fabrication of a complete denture as well as in a case of full mouth rehabilitation. Violation of the rest position would lead to detrimental effects on the facial musculature and the temporomandibular joint. This article reviews the various concepts pertaining to the rest position of mandible and its clinical implication.

Assessing the Change in Occlusal Vertical Dimension in Complete Dentures Prosthesis after Processing

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.

Predictive role of gnathological techniques for the treatment of persistent idiopathic facial pain (PIFP).

Persistent idiopathic craniofacial pain (PIFP) is a heterogeneous group of pain syndromes whose main characteristic is the daily presence of persistent pain for at least 3 months. The pathophysiology of PIFP is still not entirely known and probably related to biological and psychological factors. Although PIFP has been attributed to the central neuron activity, the importance of masticatory muscles as a possible pathogenic mechanism was recently demonstrated. The main purpose of our paper was to identify the physiological rest position of the mandible with minimal tonus of both the elevator and depressor muscles and the neuromuscular trajectory of mouth closing obtained by transcutaneous electrical stimulation (TENS) and maintained with the use of an occlusal device, known as orthotic. The VAS scale for facial pain and the migraine disability assessment score (MIDAS) index for patient quality of life were evaluated at the beginning of the study for the 38 subjects that came to our attention. Our research included two phases. The first phase consisted of kinesiographic and electromyographic (EMG) examinations of the masticatory muscles and a 45-min application of TENS in order to deprogram the muscular activity. Kinesio-electromyographic examinations were repeated in the second phase. The main evaluated parameter was jaw deflection or deviation on the sagittal and frontal planes before and after TENS during patient tooth occlusion. Patients that showed a significant modification of this parameter were treated with orthotics for 12 months. The results of a 12-month follow-up show a sharp reduction of the VAS (pre-orthotic 9.05, range 8-10, SD 0.8; post-orthotic 5.87, range 1-5, SD 0.7) and an improvement in the quality of life (MIDAS). Our study demonstrated the usefulness of TENS as a screening method for the application of orthotics. This non-invasive and/or non-painful procedure could be a useful complementary treatment in this patient population. The results of the study also confirm the role of masticatory muscle dynamics as a possible pathogenic mechanism in patients with PIFP.

Highly producible method for determination of occlusal vertical dimension: relationship between measurement of lip contact position with the closed mouth and area of upper prolabium

PurposeA new method inducing the physiologic rest position of the mandible using the lip contact position with the closed mouth have compared with those obtained using conventional methods of placing the mandible in the physiologic rest position. MethodsThe lip contact position with the closed mouth as a method was investigated whether the technique was useful for determining the occlusal vertical dimension. The relationship between the space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth and the areas of the prolabia was also investigated. ResultsMedian space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth was 1.53mm, a value intermediate between the value of 2.16mm in the resting mandibular position obtained by the conventional technique and that of 1.33mm in the swallowing position. The coefficient of variation of the space in the lip contact position with the closed mouth was significantly lower than those in the resting mandibular position and in the swallowing position. A significant positive correlation was recognized between the space in the lip contact position with the closed mouth and the area of the prolabium of the upper lip. ConclusionsThese results clarified that the lip contact position with the closed mouth obtained the excellent reproducibility comparing to the conventional methods. These findings suggested that the area of the prolabium of the upper lip might offer an effective index for individual determination of the correct free-way space.

Diseño de dispositivo de apoyo en terapias de rehabilitación a nivel distal de los dedos de la mano

In rehabilitation therapies of hand’s fingers, are developed exercises that involve effort to improve the function of movement using strength and muscle endurance for this objective. This paper presents the design of support device for rehabilitation therapies to distal level of the fingers of the hand, which includes a positional splint, an electronic device and monitoring software through a graphical user interface. The positional splint allows to place the hand and fingers in physiological rest position, in order to obtain measurements of force; this splint was first manufactured using traditional methods and then through a process of reverse engineering was scanned for its subsequent reconstruction. The electronic prototype provided information about the force applied during the therapies carried out at distal fingers of the hand level. The developed device allows supporting the realization of physical therapies at distal fingers of the hand level, and decreases the variability among different specialists in the area.

Reproducibility of the vertical dimension by different educational degrees

Background: The establishment of the correct vertical rest position is considered essential, because this position is a critical landmark in determining the vertical relation of occlusion. Unfortunately, the physiologic rest position is variable as it may be influenced by muscle tension, fatigue, and properioception. A study was therefore, undertaken to investigate the repeatability of vertical dimension measurement by different education degree groups. Materials and methods: thirty patients were investigated for vertical dimension measurement by different education degree groups (5th class undergraduate students, house officers dentists, MSc and PhD), depending on a very popular and simple method by using millimeter ruler. Result: the result showed that the difference in the vertical dimension measurements by the four different education degree groups was clinically not significant. Conclusion: 1.The vertical dimension measurements obtained from the undergraduates and house officer dentists were dependable. 2.The time-span of the measuring procedure has no effect on the determination of the vertical dimension throughout a single visit. 3.The caliper method was practical, simple and accurate in academic work. As The result of this study reveals the reproducibility of this method by all of the investigators.

A procedure for directly measuring the physiologic rest position and occlusal vertical dimension

A procedure for directly measuring the physiologic rest position and occlusal vertical dimension

Can different occlusal positions instantaneously impact spine and body posture? : A pilot study using rasterstereography for a three-dimensional evaluation.

Orthodontists influence dental occlusion directly. To suggest any link between dental occlusion and body posture is highly contentious, as evidenced by the literature. Rasterstereography, an optical technique that enables three-dimensional (3D) body measurements to be collected, has not yet been used to impartially examine whether different occlusal positions could instantaneously alter spine and body posture. We therefore set out to use this technique to nonsubjectively evaluate this question under static conditions. Optical body scans were collected for 44 subjects, using the Diers formetric 4D system, for seven different mandible positions. In total, ten spinal and body posture parameters were assessed (trunk inclination, trunk imbalance, pelvic tilt, pelvic torsion, fleche cervicale, fleche lombaire, kyphotic angle, lordotic angle, surface rotation, and lateral deviation) for each mandible position and compared with scans performed with habitual intercuspation (HIC). Significant body posture deviations were found for the fleche cervicale (positionof the mandible: right eccentrically), fleche lombaire (positionsof the mandible: physiologic rest position, cotton rolls on both sides, bite elevation 1mm), and the kyphotic angle (positionsof the mandible: cotton rolls on both sides, right eccentrically). No other significant differences were detected. Data for the parameters that varied with different dental occlusions generated high standard deviations. Therefore, within the limitations of this pilot study, we could not conclusively associate dental occlusion to an instantaneous impact on the tested parameters. The posture changes that we detected could also have arisen from individual neuromuscular compensation; a possibility that must now be ruled-in, or out, by further research studies with a higher number of subjects.

MRI assessment of temporomandibular disc position among various mandibular positions: a pilot study

Purpose: The aim of this pilot study was to assess temporomandibular joint disc movement relative to the condyle among centric relation (CR), physiologic rest position (PRP), and maximal intercuspation position (MIP) in healthy patients without signs or symptoms of any temporomandibular disorder. The hypothesis was that as the condyle rotated clockwise or translated anteriorly, the disc would also move in an anterior direction. Material and methods: Magnetic resonance images were obtained on 20 volunteers in CR, physiologic rest, and MIP. Three investigators measured the location of the disc among the different mandibular positions. Results: Disc location differences between CR and PRP exhibited the widest range of measurement. The largest amount of disc protrusion relative to the condyle was found between CR and PRP on the right side. The largest amount of disc retrusion relative to the condyle was found between CR and MIP on the right side. The hypothesis was not supported by the results. Conclusions: According to the results of this pilot study, the direction of movement of the temporomandibular disc does not correlate with the rotational movement of the condyle in hinge positions. Clinical implications: Increased knowledge of temporomandibular disc movement among various mandibular positions in asymptomatic patients may help clinicians recognize deviations in symptomatic patients.

Comparative Study of VDR and the Electrical Activity of the Anterior Temporal and Masseter Muscles using Physiologic rest Position, Phonetics and Swallowing methods

Comparative Study of VDR and the Electrical Activity of the Anterior Temporal and Masseter Muscles using Physiologic rest Position, Phonetics and Swallowing methods

A study on association and correlation of lip and finger print pattern analysis for gender identification

Background: The lip print pattern is a unique among individuals and thus helps in the identification during the forensic investigation. Lip print analysis in the forensic scene may help in the personal identification. Thus, correlating the lip print with the finger print and gender will create a new room in forensic dentistry investigation. Aim: This study aims to identify the lip and finger print pattern and to correlate lip and finger print pattern for gender identification. Materials and Methods: A total of 100 students from dental institution were included in this study. Of which, 50 were male and 50 were female.. Their aged range between 18 and 28 years with a mean age of 21.3 years. The physiological rest position of the lip print was recorded by the application of red or dark pink colored lipstick over the lips and the imprint was transferred over a white chart sheet through a transparent tape. The imprint of the finger was taken directly on a white chart sheet. The lip and finger print pattern was examined with magnifying lens. The results were analyzed using SPSS software 19.0 (Armonk, NY, USA) and presented as a descriptive statistics. A correlation of lip print with finger print and gender variation was analyzed by Pearson correlation test. Results: The study identified higher prevalence of Type II (34%) lip print pattern in the overall study population. In males, Type I lip print (42%) and plain loop finger print pattern (44%) was frequent in the study. In males, the correlation of lip and finger print patter showed weaker correlation and statistically insignificant (P = 0.436). In females, Type II lip print (34%) and plain loop finger print pattern (42%) was frequent in the study. In females, the correlation of the lip and finger print pattern showed weaker correlation with approachable statistical significance (P = 0.083). The correlation of lip and finger print with gender showed weaker correlation and approachable significance (P = 0.07). The association of lip and finger print in the study showed statistically insignificant. However, the association of Type III lip print pattern with loop finger print pattern showed statistical significant association (P = 0.05) by Chi-square analysis. Conclusion: Lip print analysis is a challenging area in the personal identification during forensic dentistry examination. The study revealed the weaker correlation and approachable significance of lip and finger print pattern in gender identification. Future studies should be encouraged in the direction of software based identification for lip and finger print analysis in gender identification. Such studies may benefit this study pattern in more accurate way.

Comparative analysis of physiologic rest position of the mandible with twins

Identical twins are multidisciplinary phenomenon, a miracle of fetal biology, medical reproductive challenge, the closest and most enduring biological connection. The aim of the research is a comparative analysis of physiologic rest of the mandible identical twins. This longitudinal oral epidemiological survey was conducted in a randomized sample of 30 pairs of identical twins, of equal gender representation and chronological age from 20 to 40 years. Based on the statistical parameters evaluated the position of physiologic rest and made a comparative analysis, that a certain degree of intra pairs similarities and differences among members of the same pair and a degree inter pairs similarities and differences among the members of different pairs of monozygotic twins. An evaluation comparing the position of physiologic rest, identical twins, t-test no significant difference in physiological rest, in the area of the front teeth. Concordance or conformity final ioshoda is proven among members of the same and different pairs. The difference was not observed, even compared to a gender. Comparing valuables of physiologic rest position, no significant intra pairs not inter pairs difference between members of the same and different MZ twin pairs.

Perbandinganantaratekniktwodot dengananalisis sefalometri pada pengukuran dimensi vertikal oklusi (Comparison between two dot technique with cephalometric analysis on the measurement of the vertical dimension of occlusion)

The vertical dimension can be described as a vertical height of the face. Practical knowledge about the physiologicalrest position is very important in determining the vertical dimension of occlusion (VDO) accurately. DeterminationVDO is one tough stage of prosthodontic treatment. There is no method or tool that can measure VDO accurately. Thisstudy can be used by dentists to help evaluate the results of VDO measurement performed by two dot technique, soconvincing dentists that the measurements are accurate. The distance was measured after the the two points on the tipof the nose and the tip of the chin assess, while DVO on the photo cephalometric measured by assessing the angle ofthe bispinal plane (SNA-SNP) with mandibular plane (Go-Gn), then OVD of cephalometric imaging was comparedwith compare the results of photo DVO cephalometric by two dots technique were measuring with Moyers standard.Based on research conducted at Dental Hospital University of Hasanuddin, there were obtained 20 samples that met the criteria as research subjects. Measuring DVO on the cephalometric photo, the mean value obtained on men20.214°and women 22.231°, insignificant statistically. It was concluded that the mean value of DVO corner was21.52°, still in the range of Moyers value with range 9-32°.

CHANGES IN THE VERTICAL DIMENSION OF OCCLUSION DURING DIFFERENT PERIODS OF COMPLETE DENTURE WEAR - a comparative study

SUMMARY: The exact determination of vertical dimension of occlusion is of great significance for the recreation of the functional, esthetical and prophylactic biological factors for the edentulous patients. Authors aim was to establish the change in mm of the vertical dimension of occlusion by patients with different duration of full dentures treatment. Materials and methods: 75 patients (44 women and 31 men) aged from 56 to 82 years, wearing complete dentures for 3 to10 years, were included in our investigation. On all patients’ plaster casts were made baseplates from photopolymerizing baseplates (TRIAD VLC Custom, Dentsply De trey) and occlusal rims from temperature resisting pink wax (Modern Pink No3 Wax, Heraeus Kulzer, Gmbh &Co.KG). The numbers of measurements of the physiologic rest position for every patient were 10. After calculating the average value of measurements the result was minimized with 2.5 mm thus giving the vertical dimension of occlusion (VDO) for the new denture treatment. Results and discussion: By 49 patients (65, 33%) the difference between the VDO with the old dentures and the new treatment was from 2 to 3.99 mm. By 17 patients (22, 67%) that difference was from 4-5.99 mm and by 9 patients (12%) - from 6-8 mm. By all the patients the VDO had to be increased with 2-6 mm by the new treatment.

The effect of the physiological rest position of the mandible on cerebral blood flow and physical balance: an observational study

Aims:There has been much published evidence that balance can improve by changing the mandible’s position relative to the maxilla as it comes together with the teeth (or oral device) as the endpoint. To help with the complexity of this topic, a definitions table* (in Appendix) has been included at the end of the manuscript for reference as needed. The aim of the current study is to evaluate whether the physiologic rest position of the jaw* (oral device overtop of the teeth as endpoint where the muscles of mastication are optimized) can have an effect on cerebral blood flow and physical balance using measurable data relative to the person’s natural, or habitual bite (teeth as endpoint) in both healthy and diseased volunteers.Methodology:Seven healthy male professional football athletes and two females with multiple sclerosis were included in this observational study, which tested the subjects in both jaw positions. Cerebral blood flow was measured non-invasively by ultrasound over the temporal region of the skull using mean flow velocity (MFV)* and pulsatility index (PI)* of the right and left middle cerebral arteries while the subject clenched the teeth together in both jaw positions. The MFV is the average speed of the blood flow in a given region of a blood vessel. The PI measures cerebral intravascular resistance. Physiologic balance of the whole body was also tested while the subjects were in both jaw positions using the y-excursion balance test* and by videotape.Results:(i) Cerebral blood flow. On the natural teeth, the MFV dropped from baseline to clenching position (mean drop −2·6±7·7 cm/second, whereas, the MFV was slightly enhanced with the physiologic rest position (PRP) [mean enhancement is 0·82±3·7 cm/second (P = 0·07)]. At baseline on natural teeth, the PI dropped slightly from baseline to clenching (mean drop 0·015±0·19). Whereas with PRP, the PI dropped by mean of 0·059±0·072 (P = 0·15). (ii) Balance. The mean balance measurement while using the PRP was 119·54±12·56 cm (P = 0·001), whereas the mean balance measurement on natural teeth was 110·72±9·47 cm. Balance improved subjectively in both MS patients on videotape.Conclusion:The physiologic rest position of the mandible might have an effect on balance by showing a trend (demonstrating a tendency) in enhancing cerebral blood flow as measured by transcranial Doppler. Further studies are needed to confirm this study’s finding.

Examination of the bioelectrical activity of the masticatory muscles during Angle's Class II division 2 therapy with an activator.

The muscles of the orofacial region have great influence on the development of dentition and occlusion formation. It is known that improper function of these muscles is one of the major etiological factors in malocclusion. A correlation between function disorders of orofacial muscle and occlusion disorders has been confirmed, as well as a correlation between the bioelectric activity of the masticatory muscles, recorded by electromyography, and bite force upon maximal voluntary contraction of these muscles. The aim of the study was to analyze the bioelectriacal activity of temporal and masseter muscles. The sample consisted of 100 subjects of both sexes, divided into the control group (n = 30) with neutral and complete dental arches, and the study group (n = 70) of patients with distal occlusion. Electromyographic measurement of bioelectric potentials in all the subjects was conducted for the examined muscles in the physiologic rest position, central mandible occlusion, and during maximal voluntary contraction of muscles and saliva swallowing, in Angle Class I and II/2 occlusal relationships, prior to treatment, after one year of the orthodontic treatment and after the treatment with an activator. Comparing the values of the bioelectrical activity in the control and the study group before the treatment, a decreased muscle activity was established in all the three positions in the study group. After the first year of orthodontic treatment the results showed an elevation in the bioelectrical activity in both muscles. After treatment with an activator, the bioelectrical activity in both muscles in the study group was higher than before the treatment, as it is confirmed by a positive highly significant coefficient of correlation. In all the three measured positions of the mandible with Angle Class II/2 malocclusion, bioelectrical activity was lowest at baseline and increased during the first year of treatment, and at the end of the treatment it partially reduced close to the approximate values in normal occlusion. Research on electromyographic activity of masticatory muscles is useful in everyday clinical practice, especially in present distinctive skeletal discrepancy before, during and after orthodontic treatment, if on the bases of the results we can evaluate the treatment, but also determine the start and duration of the retention period and retention device type.

Comparative evaluation of vertical dimension at rest before extraction, after extraction and after rehabilitation with complete denture – A Cephalometric study

IntroductionThe determination of physiologic rest position of the mandible to the maxillae is of paramount importance in almost all fields of dentistry. The stability of vertical dimension at rest has been controversial if the rest position of mandible remains constant throughout life or not. Despite of several studies on the rest position of the mandible and facial vertical dimension, certain fundamental disagreements remain unresolved. The present study aims to compare the vertical dimension at rest, before and after extraction and after rehabilitation with complete denture. Material & methodsThis study was conducted in a total of ten randomly selected patients, who had some natural teeth present with one or more opposing posterior teeth with vertical occlusal stops but were advised for extraction because of poor prognosis. Digital lateral cephalograms were done and measurements recorded at three stages: prior to extraction of remaining natural teeth, post extraction and after complete denture rehabilitation. ResultsVertical dimension at rest was found to be greatest in post rehabilitation followed by pre-extraction than post extraction state. The differences in changes were found to be statistically significant. ConclusionVertical dimension at rest shows a decrease following extraction of natural teeth, the occlusal stops, and an increase on rehabilitation. It can be stated that vertical dimension at rest is not stable position and varies following extraction of natural teeth and rehabilitation.

3-Dimensional Physiologic Postural Range of the Mandible: A Computerized-Assisted Technique—A Case Study

Previous studies demonstrated that while the mandible assumes its resting position in space, antagonistic muscles should assume minimal muscle activity within a spatial range. This zone of mandibular rest has been mapped using physiologic parameters of muscle activity and incisal spatial kinematics. This case study expands on previous research by monitoring incisal and posterior jaw position and includes lateral pterygoid muscle activity, thus allowing for determining the spatial range including additional relevant coordinates and muscle activity. Four positions were evaluated: a maximum physiologic open position, a maximum physiologic closed position, physiologic rest position, and maximum physiologic protrusion position. Within the physiologic zone of rest formed by these 4 positions, the vertical and anterior borders of the envelope of function may be documented for the incisal and posterior mandible in true 3-dimensional fashion to assist the clinician in determining a physiologic interocclusal freeway space and vertical dimension of occlusion. Advantages and limitations are discussed.