Maximal bite force and its association with temporomandibular disorders

Unravelling the Complexities of Bite Force Determinants in Paediatric Patients: A Literature Review

The amount of maximum voluntary bite force (MVBF) is determined by the combined action of the jaw elevator muscles, which are altered jaw biomechanics and reflex processes. Bite force (BF) measurements can yield valuable information on the activity and function of the jaw muscles. The accuracy of biting force measurements depends on several variables, including age, gender, malocclusion, dental caries, dental prostheses and temporomandibular joint (TMJ). This information is essential for evaluating the development and function of the masticatory system, identifying potential abnormalities or impairments and guiding appropriate treatment interventions for paediatric patients. The aim of this article is to review the literature on the factors affecting bite force and the importance of these factors in assessing dental development and guiding interventions for paediatric patients with bite force-related issues. Additionally, establishing normative values for bite force in different age groups can aid in monitoring growth and detecting any deviations from expected patterns. Measuring bite force in paediatric patients is significant in comprehensive oral health assessment and management.

Association of Non-carious Cervical Lesions with Oral Hygiene Aspects and Occlusal Force

AIM

The purpose of this case-control (CT) study was to investigate the association between the presence of non-carious cervical lesions (NCCLs) with occlusal force and other potential risk factors.

MATERIALS AND METHODS

Thirty-nine participants with NCCLs [cases (CS)] and 39 with no NCCLs [control (CT)] attending the dental clinic of the Faculdades Integradas São Pedro (FAESA), located in Brazil, were enrolled in this study. Information was collected through anamnesis, clinical examination, and a questionnaire addressing aspects related to tooth brushing, dentifrice, and mouthwash use. In clinical examination, patients were submitted to four measurements of occlusal force in the maxillary first premolars and maxillary first molars, using a strain gauge sensor of medium intensity, the Flexiforce (Tekscan, South Boston, Massachusetts, United States of America). The sensor was calibrated for the unit of measurement in Newtons (N). Data were analyzed using a student's t-test and multiple logistic regression, e with a significance level of 5%.

RESULTS

There was no statistically significant difference between the case and CT groups regarding the bite force in the four measured regions. Logistic regression identified sex as a factor significantly associated with NCCLs (p = 0.020). The odds ratio showed the female sex had more chance (OR = 6.082; CI = 1.332-27.765) of having NCCLs.

CONCLUSION

It is concluded that females presented a higher risk factor for NCCLs than men. In contrast, there was no association of occlusal force, as well as aspects related to brushing and deleterious habits.

CLINICAL SIGNIFICANCE

Females have a higher risk factor for non-carious lesions than men.

Masticatory performance in patients with jaw muscle pain: A case control study

Introduction

Masticatory function is often impaired in patients with painful temporomandibular disorders (TMD) therefore more detailed studies on comminution and mixing ability are warranted in well-defined TMD patients with chronic myalgia. Moreover, there is a need to explore the correlation between any changes in perceived pain or fatigue in such patients and the masticatory function.

Materials and methods

Self-assessments using questionnaires regarding pain, oral health, jaw function, masticatory ability, fear of movement and psychosocial signs were answered by all the participants. A series of chewing tasks involving viscoelastic food and two-colored gum was performed. Optical imaging and analyzing was conducted. Bite force as well as characteristics of pain and fatigue were assessed.

Results

In patients, the fragmented soft candy particles were less in number and had larger median of area and minimum Feret's diameter after standardized chewing compared to healthy individuals (P = 0.02). Surprisingly, the two-colored Hue-Check gum was less mixed by the healthy controls since they displayed a greater variance of the hue (P = 0.04). There were significant differences between the patients and the healthy controls in the self-assessed masticatory ability mainly regarding pain-related variables.

Conclusions

Objectively, TMD patients with chronic myalgia exhibited an impaired masticatory performance with less efficiency in comminuting soft viscoelastic food compared to the pain-free healthy control group. There was an agreement between the patients' self-assessed masticatory ability and the efficiency of their masticatory function.

The effect of anterior repositioning splint therapy on maximum bite forces in patients with disc interference disorders

OBJECTIVE

To evaluate the effect of anterior repositioning splint (ARS) on maximum bite force (MBF) values in patients with disc interference disorders (DID).

MATERIAL AND METHODS

Twenty-two patients with disc interference disorders and 22 healthy subjects participated in to study. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I have been used to diagnose DID patients. All patients received ARS therapy for 6 weeks. The MBF measurement was performed with Flexi-Force piezo-resistive sensors for both healthy subjects and patients before and after ARS therapy.

RESULTS

A significant difference was recorded by the increase of the mean MBF values after the use of the ARS in the patient with disc derangements (p < .05).

CONCLUSIONS

APS therapy is efficient for eliminating pain and increasing MBF of the patients with DID. In addition, the use of FlexiForce sensors may be a practical solution to assess the bite force in the clinical setting.

Fracture resistance of cantilevered full-arch implant-supported hybrid prostheses with carbon fiber frameworks after thermal cycling

OBJECTIVES

This in vitro study aimed to find the best combination of mesostructure and veneering materials for full-arch implant-supported hybrid prostheses (HPs) in terms of the fracture resistance (FR) of their cantilevers.

METHODS

Three groups (n = 5 each) of maxillary HPs were fabricated: Group-1 (CC-A, control): Co-Cr frameworks coated with acrylic resin; Group-2 (CF-A): carbon fiber veneered with acrylic resin; and Group-3 (CF-R): carbon fiber coated with composite resin. All specimens were submitted to 5,000 thermal cycles (5 °C - 55 °C, dwell time: 30 s), and subjected to a single cantilever bending test in a universal testing machine (crosshead speed: 0.5 mm/min) until failure. The fracture pattern was assessed using stereo microscope and SEM. The one-way ANOVA and Bonferroni tests were run (α= 0.05).

RESULTS

The FR yielded significant differences among the three groups (p< 0.001). CC-A samples reached the highest FR values (p ≤ 0.001), whereas both CF-A and CF-R HPs exhibited the comparably (p = 0.107) lowest FR. CC-A specimens failed cohesively (100%): mostly without chipping (80%). CF-A mesostructures were always broken at the connections of the distal implants. CF-R prostheses often failed adhesively (80%).

CONCLUSIONS

The HPs made of Co-Cr veneered with acrylic demonstrated the best mechanical behavior, being the only group whose 13-mm long cantilevers exceeded the clinically acceptable FR of 900 N. The HPs constructed with carbon fiber frameworks showed, additionally, more unfavorable fracture patterns.

CLINICAL SIGNIFICANCE

For HPs with cantilevers up to 13 mm, Co-Cr mesostructures coated with acrylic may represent the optimum combination of materials.

Comparison of Bite Force and the Influencing Factors Pre- and Post-cementation of Stainless Steel Crown in Children Using T-Scan

Background

In children, stainless steel crowns (SSCs) have become an invaluable restorative option for grossly decayed primary teeth. The crowns are manufactured in different sizes with preformed anatomy which requires trimming or contouring as a necessary step to fit an individual tooth. Initially, this may produce variation in the occlusal contact points yet may not result in pain or discomfort. Little research exists regarding bite force equilibration measurements in children after placing SSC, and its influencing factors such as age and gender.

Aim and objective

To evaluate and compare the measurements of bite force pre- and post-cementation of SSC using the conventional technique at maximal intercuspal position (MIP) on primary molars at different time intervals and whether age and gender influence bite force measurements.

Design

Bite force and occlusal contacts during occlusion were made using T-Scan III. Twenty children scheduled for treatment who needed SSCs were included. T-Scan measurements of the bite force and occlusal contacts of the maxilla and mandibular teeth were recorded and analyzed before and immediately after cementation of SSC later 4 weeks during the follow-up period. These measurements were correlated with age and gender influence.

Results

There was no significant result in the percentage of bite force on the crowned tooth (placement of SSC) at different time intervals. Prematurities were present in all the groups but a significant reduction was seen on the crowned tooth from baseline to 1-month follow-up (p = 0.03). Also, a statistically significant increase in the bite force was seen in >7 years of age (p = 0.006) and no statistical significance among the gender.

Conclusion

Following the standard tooth preparation, the SSC will continue to appear clinically acceptable for many years. Our study children showed an adaptable masticatory system irrespective of age and gender during growth and development.

How to cite this article

Aishwarya N, Nagarathna C, Poovani S, et al. Comparison of Bite Force and the Influencing Factors Pre- and Post-cementation of Stainless Steel Crown in Children Using T-Scan. Int J Clin Pediatr Dent 2021;14(1):46-50.

The ontogeny of maximum bite force in humans

Ontogenetic changes in the human masticatory complex suggest that bite force, a key measure of chewing performance, increases throughout growth and development. Current published bite force values for humans exist for molar and incisal biting, but few studies measure bite forces across all tooth types, or measure bite force potentials in subjects of different ages. In the absence of live data, models of bite force such as the Constrained Lever Model (CLM), are employed to predict bite force at different bite points for adults, but it is unclear whether such a model can accurately predict bite force potentials for juveniles or subadults. This study compares theoretically derived bite forces and live bite force data, and places these within an ontogenetic context in humans. Specifically, we test whether (1) patterns of maximum bite force increase along the tooth row throughout ontogeny, (2) bite force patterns estimated using the CLM match patterns observed from live bite force data, and (3) changes in bite forces along the tooth row and throughout ontogeny are associated with concomitant changes in adductor muscle leverage. Our findings show that maximum bite forces increase throughout ontogeny and change along the tooth row, with the highest forces occurring at the posterior dentition. These findings adhere to the expectations under the CLM and validate the model's utility in predicting bite force values throughout development. Furthermore, adductor muscle leverage values reflect this pattern, with the greatest leverage values occurring at the posterior dentition throughout ontogeny. The CLM informs our study of mammalian chewing mechanics by providing a model of how morphological changes of the masticatory apparatus during ontogeny affect bite force distribution along the tooth row. Furthermore, the decreased bite force magnitudes observed in juveniles and subadults compared with adults suggest that differences in juvenile and subadult diets may partially be due to differences in bite force production potentials.

Development of a bite force transducer for measuring maximum voluntary bite forces between individual opposing tooth surfaces

Bite forces are studied in order to understand a wide range of factors pertaining to the mastication system. Various strain gauge transducers have been employed to measure bite forces, with several descriptions of these available in the literature; unfortunately, many reports provide insufficient detail to enable accurate reproduction. The aim of this project was to develop a bite force transducer with the capability of measuring maximum voluntary bite forces between individual opposing tooth surfaces. Furthermore, in an attempt to address the issue of vague device descriptions in the available literature, a detailed account of the transducer development has been included. A novel strain gauge transducer was designed and built. Bite forces of forty individuals were measured to verify the capabilities and clinical application of the device.

Comparative study of molar and incisor bite forces regarding deciduous, mixed, and definitive dentition

OBJECTIVE

To compare maximum incisor (MBFinc) and molar (MBFmol) bite forces regarding the type of dentition and sex and to establish a relationship between them.

METHODS

One hundred-five individuals were divided into 3 groups: G1 - 22 females/13 males (4-5 years); G2 - 15 females/20 males (11-12 years); and G3 - 16 females/19 males (17- 18 years). The maximum bite force was recorded with an extraoral measuring device. Three measurements were recorded: right and left molar level (MBFmol) and incisor level (MBFinc). The ratio %MBFinc/MBFmol was determined.

RESULTS

MBFmol and MBFinc values increased with age (p < 0.05). MBFmol showed statistically higher values than MBFinc (p < 0.05), when compared within the same group.

CONCLUSION

MBFinc and MBFmol increased with age. For all groups, MBFmol showed higher values than MBFinc, and %MBFinc/MBFmol ratio was 1:2. No differences were found in maximum bite force between sexes.

Evaluation of Fracture Resistance and Sites of Failure of Different Dowel Core Restorations: An In-Vitro Study

Background:

Dowel Cores are often required in endodontically treated tooth to aid retention and resistance for a final prosthetic crown. Studies concerning the role of post-core systems on the fracture resistance with different dowel material remain controversial.

Aim:

This experimental study aimed to investigate the fracture resistance strength and failure mode of 3 dowel systems (glass fiber, indirect resin, and prefabricated metal with resin core).

Methods:

Twenty-one extracted human maxillary central incisors were first endodontically treated and then separated into 3 equal groups randomly;1st group consisted of glass fiber dowel, 2nd group consisted of indirect resin dowel, and 3rd group consisted of the prefabricated metal dowel. All specimens were restored with resin core and indirect resin crown. A testing force was applied with a universal testing machine (at 135 o angle) at 3 mm from the incisal edge of crown and forces were measured. Statistical tests were done using One-way ANOVA and Chi-square Test.

Results:

There was no significant difference (P-value >0.05) of the fracture resistance among glass fiber dowel, indirect resin dowel and pre-fabricated dowel with indirect resin crown. The prefabricated metal dowel had maximum fracture resistance (566 ±157.771 N) followed by Glass fiber dowel (541.047 ±199.571 N) and indirect resin dowel and post (444.550 ±139.788 N).

Conclusion:

Glass fiber dowel, indirect resin dowel and prefabricated metal dowel with resin core and indirect resin crown systems showed statistically insignificant fracture strength values and mode of failure.

Voluntary biting behavior as a functional measure of orofacial pain in mice

INTRODUCTION

Pain-related behavior secondary to masticatory function can be assessed with the rodent bite force model. A reduction of the bite force has been shown to be related to pain associated with the masseter muscle and jaw activity, while an increase in bite force suggests improvement of muscle function and less pain. To evaluate the usefulness of the bite force measure in studying long-lasting orofacial pain we analyzed biting parameters during prolonged myofascial pain induced by ligation injury of the masseter muscle tendon (TL) in mice.

METHODS

C57Bl/6 mice were habituated to bite at a pair of aluminum plates attached to a force displacement transducer. The transduced voltage signals were amplified and converted to force through calibration with a standard weight set. Voluntary biting behavior was recorded for 100 s/session and those with bite forces ≥980 mN were analyzed. Nociception was also verified with von Frey, conditioned place avoidance (CPA) tests and mouse grimace scale. Persistent orofacial pain was induced with unilateral ligation of one tendon of the masseter muscle (TL).

RESULTS

To reduce interference of random bites of smaller forces, the top 5 or 15 bite forces (BF5/15) were chosen as a measure of masticatory function and related to pain behavior. Both male and female mice exhibited similar BF5/15. For the first nascent test of all mice, mean bite force was significantly and positively correlated with the body weight. However, this correlation was less clear in the latter tests (2-8 w). TL induced a reduction of BF5/15 that peaked at 1 w and returned to the baseline within 3 w. The von Frey and CPA tests indicated that mechanical allodynia/hyperalgesia persisted at the time when the BF had returned to the pre-injury level. Infusion of pain-relieving bone marrow stromal cells improved biting behavior in both male and female mice as shown by significantly increased BF5/15, compared to vehicle-treated mice.

CONCLUSIONS

Mouse voluntary biting behavior can be reliably measured and quantified with a simplified setup. The bite force showed an inverse relationship with the level of pain after TL and was improved by pain-relieving manipulations. However, the injury-induced reduction of bite force peaked early and did not parallel with other measures of nociception in the later phase of hyperalgesia. The results suggest that multiple factors such as the level of habituation, cognitive motive, physical status, and feeding drive may affect random voluntary biting and confound the biting parameters related to maintained hyperalgesia.

Assessment of the impact of temporomandibular disorders on maximum bite force

AIM

Temporomandibular disorders (TMD) refer to functional disorders of the masticatory system, temporomandibular joint (TMJ) and masticatory muscles. The main objective of this study was to determine whether and to what extent temporomandibular disorders (TMD) affect the maximum bite force (MBF).

METHODS

The present study included subjects with and without temporomandibular disorder. The presence of TMD was assessed by means of the Helkimo clinical dysfunction index analysis. We measured the maximum bite pressure (MBP) and occlusal contact area (OCA) by means of a Fuji Prescale Pressure measurement film. Based on the MBP and OCA values obtained, MBF values were determined.

RESULTS

The MBF values were significantly lower in patients with TMD compared to subjects without TMD (P Conclusion: TMDs have a significant impact on MBF and masticatory muscle action potential. More research is needed to determine the impact of reduced maximum bite force on the functional efficiency of the masticatory system.

Influence of anthropometry, TMD, and sex on molar bite force in adolescents with and without orthodontic needs

PURPOSE

Bite force has been studied as representative of functional indices of mastication and its value may have diagnostic significance in disorders of the musculoskeletal system of facial bones. This study aimed to evaluate bite force in adolescents with and without orthodontic needs considering presence of temporomandibular disorders (TMD) as well as anthropometry: craniofacial dimensions and body mass index (BMI).

METHODS

A total of 80 subjects were screened (61 females, 19 males; 18 ± 3 years old). Unilateral molar bite force was measured using a digital dynamometer with a fork thickness of 12 mm. Direct anthropometry was used to quantify craniofacial measurements. Dental Health Component of the Index of Orthodontic Treatment Need (IOTN-DHC) and the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were used to classify samples according to malocclusion and to TMD, respectively. Data were analyzed using normality tests, Mann-Whitney U test, and multiple linear regression analyses with stepwise backward elimination, controlling for the presence of malocclusion and TMD (p ≤ 0.05).

RESULTS

The cephalic index was greater in females with malocclusion and the longitudinal cranial diameter was reduced in females with malocclusion. BMI was not different between normal and malocclusion groups for either gender. Bite force was negatively related with vertical dimension of the face, and positively related with facial width and facial index. The model explained 32% of bite force variability, considering the sample size (coefficient of determination R ² = 0.324).

CONCLUSIONS

Even when orthodontic needs and TMD signs and symptoms are present, stronger bite force is still observed in males and in subjects with smaller anterior facial heights and wider facial widths.

Fracture behavior of single-structure fiber-reinforced composite restorations

Objective: The applications of single-structure fiber-reinforced composite (FRC) in restorative dentistry have not been well reported. This study aimed to clarify the static mechanical properties of anterior crown restorations prepared using two types of single-structure FRC. Materials and methods: An experimental crown restoration was designed for an upper anterior incisor. The restorations were made from IPS Empress CAD for CEREC (Emp), IPS e.max^® CAD (eMx), experimental single-structure all-FRC (a-FRC), Filtek™ Supreme XTE (XTE), and commercially available single-structure short-FRC (everX Posterior™) (n = 8 for each material) (s-FRC). The a-FRC restorations were prepared from an experimental FRC blank using a computer-aided design and manufacturing (CAD/CAM) device. A fracture test was performed to assess the fracture load, toughness, and failure mode. The fracture loads were vertically applied on the restorations. The surface micromorphology of the FRC restorations was observed by scanning electron microscopy (SEM). The data were analyzed by analysis of variance (p = .05) followed by Tukey's test. Results: s-FRC showed the highest mean fracture load (1145.0 ± 89.6 N) and toughness (26.2 ± 5.8 Ncm) among all the groups tested. With regard to the micromorphology of the prosthetic surface, local crushing of the fiberglass was observed in s-FRC, whereas chopped fiberglass was observed in a-FRC. Conclusions: The restorations made of short-FRC showed a higher load-bearing capacity than those made of the experimental all-FRC blanks for CAD/CAM. The brittle-like fractures were exhibited in the recent dental esthetic materials, while local crushing fractures were shown for single-structure FRC restorations.

Does pain in the masseter and anterior temporal muscles influence maximal bite force?

OBJECTIVE

The aim of this study was to evaluate changes in pain and muscle force, and the relationship between them, in patients with muscle pain and bruxism, prior to and after treatment.

METHODS

Thirty women with bruxism and myofascial pain (Ia) were included in this study. Sleep bruxism diagnosis was made based on clinical diagnostic criteria, and awake bruxism diagnosis was made by patient questionnaires and the presence of tooth wear. The diagnosis of myofascial pain was established according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC-TMD). Dentulous or partially edentulous patients (rehabilitated with conventional fixed prostheses) were included in the study according to the inclusion and exclusion criteria. The pain treatment protocol included occlusal splints, patient education, and physiotherapy for 30days. Bite force was measured using a dynamometer at the central incisor and the first molar regions on both sides. The exams were performed at baseline, after 7days, and 30days after treatment. The Wilcoxon test was used to compare patient pain level response among the periods analyzed in the study. Bite force data were submitted to two-way repeated-measures ANOVA, followed by the Tukey HSD test (p<0.05). A simple regression analysis was performed to verify the relation between pain level and bite force.

RESULTS

Results revealed that there was a statistical difference in pain level over time for both muscles and sides (p<0.01). In the molar region, the bite force exhibited significantly higher values after 30days of treatment, when compared with the baseline (p<0.001). There was a correlation between pain level and bite force only for the temporal muscle in all periods analyzed (p<0.05). There was no strong correlation in the response level points to support the association of pain and bite force.

CONCLUSIONS

Pain level decreased and bite force increased in the molar region after treatment. No strong correlation or dispersion in the relationship between pain levels and bite force was seen in women with myofascial pain and bruxism.

Relined Fiberglass Post: Effect of Luting Length, Resin Cement, and Cyclic Loading on the Bond to Weakened Root Dentin

This study evaluated the effects of luting length of the post, the resin cement, and cyclic loading on pull-out bond strength of fiberglass posts relined with composite resin in weakened roots. The canals of 80 bovine incisors were endodontically treated and weakened with diamond burs. The teeth were randomly divided into eight groups (n=10) according to the luting procedures of the relined fiberglass post (RFP): In groups 1, 2, 3, and 4, the RFPs were luted with RelyX ARC, and in groups 5, 6, 7, and 8 they were luted with RelyX U200. In groups 1, 3, 5, and 7, the RFPs were luted at a length of 5 mm, and in groups 2, 4, 6, and 8 they were luted at a length of 10 mm. Specimens from groups 3, 4, 7, and 8 were submitted to cyclic loading. Specimens were subjected to a pull-out bond strength test in a universal testing machine. The results (MPa) were analyzed by three-way analysis of variance and the Tukey post hoc test (α=0.05). Six human upper anterior teeth were used to analyze the bond interface by confocal laser scanning microscopy (CLSM). The pull-out bond strength of RFPs luted with RelyX U200 was statistically higher than that of RelyX ARC. Cyclic loading influenced the bond strength only for the luting length of 5 mm. CLSM analysis revealed the formation of resin cement tags for both materials. Luting length is an important factor in retaining RFPs in weakened roots when they are subjected to cyclic loading, and RelyX U200 resulted in greater bond strengths to the root canal in comparison with RelyX ARC.

Temporomandibular disorders. Part 1: anatomy and examination/diagnosis

Temporomandibular disorders (TMD) are a heterogeneous group of diagnoses affecting the temporomandibular joint (TMJ) and surrounding tissues. A variety of methods for evaluating and managing TMD have been proposed within the physical therapy profession but these sources are not peer-reviewed and lack updates from scientific literature. The dental profession has provided peer-reviewed sources that lack thoroughness with respect to the neuromusculoskeletal techniques utilized by physical therapists. The subsequent void creates the need for a thorough, research informed, and peer-reviewed source regarding TMD evaluation and management for physical therapists. This paper is the first part in a two-part series that seeks to fill the current void by providing a brief but comprehensive outline for clinicians seeking to provide services for patients with TMD. Part one focuses on anatomy and pathology, arthro- and osteokinematics, epidemiology, history taking, and physical examination as they relate to TMD. An appreciation of the anatomical and mechanical features associated with the TMJ can serve as a foundation for understanding a patient's clinical presentation. Performance of a thorough patient history and clinical examination can guide the clinician toward an improved diagnostic process.

Maximum bite force analysis in different age groups

Introduction Maximum bite force (MBF) is the maximum force performed by the subject on the fragmentation of food, directly related with the mastication and determined by many factors. Objective Analyze the MBF of subjects according to age groups. Methods One hundred individuals from the city of São Paulo were equally divided according to age groups and gender. Each individual submitted to a myotherapy evaluation composed of anthropometric measurements of height and weight to obtain body mass index (BMI), using a tape and a digital scale (Magna, G-life, São Paulo), and a dental condition and maximum bite force evaluation, using a digital dynamometer model DDK/M (Kratos, São Paulo, Brazil), on Newton scale. The dental and bite force evaluations were monitored by a professional from the area. Analysis of variance was used with MBF as a dependent variable, age group and gender as random factors, and BMI as a control variable. Results Till the end of adolescence, it was possible to observe a decrease in MBF in both sexes, with the male force greater than the female force. In young adults, the female force became greater the males, then decreased in adulthood. There was no correlation between MBF and BMI. Conclusion There are MBF variations that characterizes the human development stages, according to age groups.

Evaluation of orofacial function in temporomandibular disorder patients after low-level laser therapy

OBJECTIVE

To evaluate the effect of low-level laser therapy on occlusal contact area, occlusal pressure and bite force in temporomandibular disorder patients.

PATIENTS AND METHOD

Twenty patients (14 women, six men, mean age 33.1 ± 3.8 years) diagnosed with myofascial pain according to the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) participated in the study. Twenty healthy individuals, matched in age and gender, served as a control group. Low-level laser was applied to the mastication muscles three times per week, for a total of 10 sessions. The mandibular mobility range was evaluated. The maximum bite force, occlusal contact area and occlusal pressure were measured bilaterally with a dental pre-scale before and after treatment. All variables were analyzed descriptively. Changes in the masticatory muscle tenderness, mandibular movements, maximum bite force, occlusal contact area and occlusal pressure were compared by paired-sample Student's t-tests.

RESULTS

There was a significant increase in the pressure pain threshold of the examined muscles. Mandibular movements were significantly improved in all patients. There was also a significant decrease in pain by palpation after laser exposure. However, no significant change was found in the maximum bite force, occlusal contact area or occlusal pressure after the treatment and also the values after the treatment were still significantly lower than those of the healthy individuals.

CONCLUSION

This particular type of LLLT is effective at relieving pain but does not provide physical improvement.

Wear of double crown systems: electroplated vs. casted female part

OBJECTIVES

The wear of telescopic crowns is a common problem often reducing the patient's satisfaction with the denture and resulting in a renewal of the denture. The study aims to compare the wear behavior of conical crowns using electroplated copings (group E ) with standard telescopic crowns with cast female parts (group C).

MATERIAL AND METHODS

10 conical crowns were milled for each group of a cast gold alloy. The specimen of group E had a conicity of 2º. The cast secondary crowns of group C had a 0º design. The electroplated coping was established by direct electroforming. An apparatus accomplishing 10,000 wear cycles performed the wear test. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long term wear period. The retention force value and the force-distance integral of the first 0.33 mm of each cycle were calculated.

RESULTS

The retentive forces were significantly higher for group E and the integrals were significantly lower for this group except the integral at cycle 10,000. The changes of retention force and integral did not differ significantly between both groups in all phases. The change of the integrals as well as the integral at the particular cycles showed higher interquartile distances for group C.

CONCLUSIONS

Within the limitations of this study the tested conical crowns showed clinically acceptable retentive properties. The values reached a range comparable to retentive elements tested in recent literature. The values of group C showed higher ranges. The force measured for group E was significantly higher than for group C but the integrals showed an opposite tendency. The results indicate that an exclusive analysis of the force is not sufficient as the integral is not equivalent to the force although it describes the retentive property of the system in a better way than the force over a distance is described. Both systems seem to be suitable for clinical practice.

Novel system for bite-force sensing and monitoring based on magnetic near field communication

Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient's dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system's operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials.

Effect of occlusal splint therapy on maximum bite force in individuals with moderate to severe attrition of teeth

OBJECTIVE

The purpose of the pilot study was to determine the effect of restoring lost occlusal vertical dimension (OVD) due to attrition on maximum bite force in humans.

METHODOLOGY

A total of 124 subjects in age range of 25-40 years, with moderate to severe attrition, having full complement of teeth were screened according to inclusion and exclusion criteria. After consent, occlusal vertical dimension was assessed by employing mechanical and physiological methods in the experimental group and a maxillary canine guided hard splint was fabricated for each subjects fulfilling inclusion criteria and with positive consent (78). Bite force in experimental group was measured before, immediately after delivery of splint and subsequently at an interval of four, eight, and twelve weeks. Due loss during follow up, only 50 subjects could be available for bite force recording till 12 weeks. Bite force of age, gender, height and weight matched controls with no signs of attrition was also measured for comparison.

RESULTS

Bite force of the experimental group was found to be significantly less than the matched controls (P=0.000) initially. After delivery of splint, bite force values increased progressively till twelve weeks. However comparison of bite force values of experimental group with control group showed no significant difference at end of eight (P=0.008) and twelve weeks (P=0.162).

CONCLUSION

It was concluded that maximum bite force increases with restoration of lost vertical using splint therapy. A time period of 8-12 weeks is required to restore the maximum bite force value approximately similar to matched controls.