Comprehensive Deciphering the Complexity of the Deep Bite: Insight from Animal Model to Human Subjects

Deep bite is a malocclusion phenotype, defined as the misalignment in the vertical dimension of teeth and jaws and characterized by excessive overlap of the upper front teeth over the lower front teeth. Numerous factors, including genetics, environmental factors, and behavioral ones, might contribute to deep bite. In this study, we discuss the current clinical treatment strategies for deep bite, summarize the already published findings of genetic analysis associated with this complex phenotype, and their constraints. Finally, we propose a comprehensive roadmap to facilitate investigations for determining the genetic bases of this complex phenotype development. Initially, human deep bite phenotype, genetics of human deep bite, the prevalence of human deep bite, diagnosis, and treatment of human deep bite were the search terms for published publications. Here, we discuss these findings and their limitations and our view on future strategies for studying the genetic bases of this complex phenotype. New preventative and treatment methods for this widespread dental issue can be developed with the help of an understanding of the genetic and epigenetic variables that influence malocclusion. Additionally, malocclusion treatment may benefit from technological developments like 3D printing and computer-aided design and manufacture (CAD/CAM). These technologies enable the development of personalized surgical and orthodontic guidelines, enhancing the accuracy and effectiveness of treatment. Overall, the most significant results for the patient can only be achieved with a customized treatment plan created by an experienced orthodontic professional. To design a plan that meets the patient's specific requirements and expectations, open communication between the patient and the orthodontist is essential. Here, we propose to conduct a genome-wide association study (GWAS), RNAseq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro and small RNA, and long noncoding RNA analysis in tissues associated with deep bite malocclusion in human, and complement it by the same approaches in the collaborative cross (CC) mouse model which offer a novel platform for identifying genetic factors as a cause of deep bite in mice, and subsequently can then be translated to humans. An additional direct outcome of this study is discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for early identification of patients carrying the susceptible genetic factors so that we can offer early prevention and treatment strategies, a step towards applying a personalized medicine approach.

Evaluation of condyle-fossa relationships in skeletal Class I malocclusion with variable degrees of deep overbite and open bite

OBJECTIVE

To compare the temporomandibular joint (TMJ) position and shape between skeletal Class I subjects with different degrees of deep overbite or open bite and unaffected peers.

METHODS

Cone beam computed tomography (CBCT) images of 90 participants, equally divided into deep bite, open bite, and control groups (DBG, OBG, and CG, respectively), were analyzed. The DBG and OBG were further subdivided into three subgroups based on the severity. Linear and angular measurements were used to determine the positional and morphological characteristics of the TMJ.

RESULTS

DBG showed significantly larger superior joint space, anterior inclination of the condyle, and articular eminence inclination than CG and OBG. The severity of deep bite and open bite significantly influenced the TMJ position and morphology.

CONCLUSION

In severe deep overbite and open bite cases, there were considerable alterations in TMJ components, most likely as a result of functional demands.

Temporomandibular disorders, bite force and osseous changes of the temporomandibular joints in patients with hypermobile Ehlers-Danlos syndrome compared to a healthy control group

Background

Ehlers‐Danlos syndrome (EDS) is a hereditary disorder that affects the connective tissue and collagen structures in the body characterised by joint hypermobility, skin hyperextensibility and tissue fragility.

Objective

The aim was to investigate temporomandibular disorders (TMD), bite force, teeth in occlusal contact and osseous changes of the temporomandibular joints (TMJs) in 26 patients with hypermobile EDS (hEDS), differentiated by a genetic test, compared to 39 healthy controls.

Methods

Clinical examination according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), radiological examinations of the TMJs by cone‐beam‐computed tomographic (CBCT) scans, registration of bite force and teeth in occlusal contact was performed. Statistical analyses included Fisher's Exact Test, multiple logistic and linear regression models adjusted for age, gender and Body Mass Index (BMI).

Results

Single symptoms and signs of TMD occurred significantly more often in hEDS (p = .002; p = .001; p = .003; p = <.0001; p = .012) and maximum mouth opening was significantly smaller in hEDS compared to controls (p = <.0001). The DC/TMD diagnosis myalgia, myofascial pain with referral, arthralgia, headache attributed to TMD, disc displacement disorders and degenerative joint disease occurred significantly more often in hEDS compared to controls (p = .000; p = .008; p = .003; p = .000; p = <.0001; p = .010, respectively). No significant differences were found in bite force and in teeth in occlusal contact between the groups (p > .05). On CBCT of the TMJs, subcortical sclerosis occurred significantly more often in hEDS compared to controls (p = .005).

Conclusion

Symptoms and signs of TMD and osseous changes of the TMJs occurred significantly more often in hEDS. Bite force and teeth in occlusal contact were comparable to controls.

Three-dimensional assessment of temporomandibular joint in skeletal Class I malocclusion with variable degrees of overbite and overjet

OBJECTIVE

To three-dimensionally evaluate the position and morphology of the TMJ in skeletal Class I with variable degrees of overbite and overjet in comparison with normal peers.

METHODS

Pretreatment CBCT scans of 126 adults were retrieved. Based on the severity of overjet and overbite, the sample was divided into three main groups and six subgroups (18 patients each): the first group with a normal overbite and variable overjet degree and the second group with normal overjet and variable overbite degree. These six subgroups were compared with a third control group of normal overjet and overbite.

RESULTS

There were significant differences in vertical condylar position, vertical and anteroposterior condylar inclinations, condylar height, and significant posterior condylar positioning in severe deep overbite, compared with the control group.

CONCLUSION

There were significant changes in the TMJ components in severe deep overbite cases. Therefore, sever deep overbite could be considered a predisposing factor for temporomandibular disorders.

Bite Force, Occlusal Contact and Pain in Orthodontic Patients during Fixed-Appliance Treatment

Previously, bite force, occlusal contact and pain were investigated in orthodontic patients with moderate-to-severe malocclusion, but not in patients with minor malocclusion. The purpose of this study was to investigate changes in bite force, teeth in occlusal contact and pain in orthodontic patients with minor crowding before orthodontic treatment (T0), after bonding (T1), during treatment (T2), post-treatment (T3) and during retention (T4). In total, 27 patients (21 females, 6 males, median age 15.3 years) with neutral occlusion and normal craniofacial morphology were treated with non-extractions and fixed appliances. Differences in the registered data were analysed by a mixed linear model with repeated measures. Bite force and teeth in occlusal contact significantly decreased between T0 and T1 (p < 0.0001, respectively) and between T0 and T2 (p < 0.01, respectively). Bite force and teeth in occlusal contact significantly increased between T1 and T4 (p < 0.05, p < 0.0001, p < 0.001, respectively) and between T2 and T4 (p < 0.05, p < 0.0001, p < 0.01, respectively). No significant difference in pain was found. The results indicate that bite force and teeth in occlusal contact significantly decreased during treatment and reached baseline level at retention. The findings may prove valuable for informing orthodontic patients with minor malocclusion.

Revisiting the Risk Factors for Multiple Symptoms of Temporomandibular Disorders: A structured Cross-sectional Study

Background:

The risk factors for Temporomandibular Disorders (TMD) are extensively studied, but the results showed no consistency. Only a small proportion of patients with TMD are likely to seek help and require treatment. Those individuals tend to present with multiple symptoms. This cohort of patients was not well investigated.

Objective:

The study aimed to examine the association between possible risk factors for presentation with multiple TMD symptoms.

Methods:

A population-based, cross-sectional study was conducted across 2101 individuals with an age range of 19-60 years. The condition was assessed via a detailed questionnaire comprising symptoms, habits, dental history, general health, sleep patterns, along with the completion of the Hospital Anxiety and Depression (HAD) scale, followed by an examination of the hypothesized clinical signs. The obtained data were tabulated and characterized the study population in a descriptive analysis in forms of percentages and frequencies. The significance level was set at P-value less than or equal to 0.005. The chi-squared test was implemented to assess the relationship between the multiple TMD symptoms reported and the potential risk factors.

Results:

Most participants reported a variable amount of stress. Moreover, 1528 (72.7 percent) mentioned abnormalities in sleep. About 80 percent had at least one TMD-related symptom. The multiple symptoms of TMD were identified among the 741 individuals. The following risk factors demonstrated association with a robust statistical significance (P=0.00), 1) occupation, 2) sleeping problems, 3) health concerns, 4) traumatic dental treatment, 5) various somatic symptoms, and 6) elevated HAD scale. When the outcomes of the clinical examination were analyzed, the statistical assessment could link soft tissue changes, namely; the cheek ridging and tongue indentations (P 0.00), with multiple symptoms of the condition.

Conclusion:

Multiple TMD symptoms were prevalent among individuals with elevated stress, abnormal sleep pattern, traumatic dental treatment, elevated HAD scale. The results highlighted the importance of psychological factors in the pathogenesis of TMD.

The study of facial morphology in patients with vertical growth pattern (hyperdivergent) lacking or showing temporomandibular disorders symptoms

AIM

According to the large number of studies, there seems to be a significant relation between hyperdivergence growth pattern and temporomandibular disorders. However, it is not clearly scrutinized which morphological factors can contribute to the development of temporomandibular disorders. The aim of this study was to investigate the relation between some skeletal and facial morphologic features of hyperdivergent facial growth pattern patients and temporomandibular disorders.

MATERIALS AND METHODS

This case-control study was performed on a population of 50 patients including 25 patients with temporomandibular disorder and 25 non- temporomandibular disorder individuals aged between 15-30 years with hyperdivergent growth pattern (Frankfurt Mandibualr plane angle between 28 and 35 degree). Two groups of symptomatic and asymptomatic patients (case and control) were matched for age and gender. In order to evaluate the skeletal and dental variables, lateral cephalometries was taken and traced after obtaining written consent from the patients. The measured variables were A point to Nasion to B point, Frankfurt plane to Nasion to Pogonion, Nasion to A point to Pogonion, Sella to Gnathion to Frankfurt plan, Articular point to Gonion-Menton, Sella to Articular point to Gonion, Palatal plane to Mandibular plane, and Articular point to Gonion angles. The intervals of Basion to Nasion, Sella to Basion, Gonion to Menton, and amounts of Anterior facial height meas, Upper Anterior facial height ratio to Lower Anterior facial height, posterior facial height, overjet, and overbite Data were analyzed by Chi² test, t-test, and multivariate test.

RESULTS

According to the descriptive statistics, the age of the control and case groups averaged 21.12±1.99 and 21.63±1.58 years respectively. Among the people referred to the dental school, the frequency of males and females in the control and case groups were 6, 7 and 19, 18 respectively. The results of t-test and multivariate tests indicated significant differences between the two variables of overbite and mandibular length.

CONCLUSION

The present study revealed increased overbite (dental feature) and mandibular length (skeletal feature) is more likely to be associated with a higher risk of temporomandibular disorders joint disease in patients with hyperdivergent facial growth pattern.

CLINICAL SIGNIFICANCE

Treatment of the deep bite condition can be helpful in improving temporomandibular disorder.

The prevalence of posterior crossbite, deep bite, and sleep or awake bruxism in temporomandibular disorder (TMD) patients compared to a non-TMD population: A retrospective study

Objective: To assess the prevalence of posterior crossbite and/or deep bite among patients diagnosed with temporomandibular disorders (TMD) compared to a non-TMD population.Methods: Four hundred ninety-four patients were enrolled: 345 with TMD according to the diagnostic criteria for TMD and 149 without TMD (control group). The chi-square test was used for statistical analysis.Results: A statistically significant association was found between sleep and awake bruxism and painful TMDs (p < .001 for both), but not with disc displacement. There was no association between posterior crossbite and/or deep bite with either painful TMD or disc displacement.Conclusion: Within the study limitations, sleep bruxism and awake bruxism may be related to pain in the TMD, and the severity of a deep overbite and presence of a unilateral or bilateral posterior crossbite should not be considered risk factors or as having any effect on the pain associated with TMD and/or disc displacement.

Prevalence of malocclusion, oral parafunctions and temporomandibular disorder-pain in Italian schoolchildren: An epidemiological study

BACKGROUND

The prevalence of malocclusion, temporomandibular disorders (TMD) and oral parafunctions is highly debated in children population.

OBJECTIVES

To investigate the prevalence of malocclusion, self-reported oral parafunctions and TMD-pain in Italian schoolchildren and to assess the association between the examined factors.

METHODS

A total of 700 children aged 9-11 years were selected among six public schools in Campania region (Italy). Molar relationship, overjet, overbite and cross-bite were assessed through a clinical examination. Furthermore, the subjects were demanded to fill in a validated questionnaire for TMD-pain screening and the short form of the Oral Behaviours Checklist. Descriptive statistics were used to report the frequencies. The associations between occlusal traits, oral parafunctions and TMD-pain were analysed with a Pearson chi-square test, as expressed by odds ratio and 95% confidence intervals. The significance level was set at P < 0.05.

RESULTS

Molar Class I was the most frequently encountered molar relationship, followed by molar Class II, subdivision and molar Class III. Increased overjet was more common than negative overjet. Posterior cross-bite was observed in 12% of children. TMD-pain was recorded in 14.7% of subjects. High frequency of oral parafunctions was reported in 21.3% of subjects. A significant association was found between TMD-pain and negative overbite. Cross-bite and high frequency of oral parafunctions were associated with TMD-pain.

CONCLUSION

The current results show that malocclusion, self-reported oral parafunctions and TMD-pain are frequent findings among Italian schoolchildren and that some occlusal factors and high frequency of oral parafunctions might be associated with TMD-pain.

Effects of short-term acupuncture treatment on occlusal force and mandibular movement in patients with deep-bite malocclusion

Background/purpose

Acupuncture is well known to be effective for pain relief and muscle relaxation, and hence it is feasible that acupuncture treatment could change the occlusal forces and mandibular movements in subjects with deep-bite malocclusion. The purpose of this research was to determine the distribution of occlusal force and the border movement of the mandible in patients with deep-bite malocclusion before and after acupuncture treatment.

Materials and methods

This study involved 17 volunteers with deep-bite malocclusion and aged 20-30 years. Before and after acupuncture treatment, the distribution of the occlusal-force percentage at each tooth was measured and the percentage biting force in the first molar area during maximal clenching was recorded. Additionally, the mandibular movements including the maximum mouth opening and maximum lateral border movement were also evaluated. All of the data were analyzed statistically using the Wilcoxon signed-rank test.

Results

The percentage biting force at the first molar differed significantly between before and after the acupuncture treatments (P = 0.017). However, no treatment effects were seen for the maximum mouth opening and the maximum lateral border movement. Conclusion: Although the mandibular border movements did not change significantly, this study has confirmed that acupuncture treatment may become an alternative choice on improving the occlusal force of deep-bite patients.

Association between posterior crossbite and/or deep bite and temporomandibular disorders among Palestinian adolescents: A sex comparison

Objective: To assess the prevalence of temporomandibular disorders (TMDs) and posterior crossbite and/or deep bite and any possible association between them. Methods: One thousand-nineteen adolescents responded to a questionnaire regarding oral habits and TMD symptoms. Afterwards, they were diagnosed according to the Axis I of the DC/TMD and underwent a dental examination. The chi-square test was used for statistical analysis. Results: A significant association  was found between posterior crossbite and some TMD diagnosis, but no association was found between deep bite and TMD, nor between occlusal diagnosis and bruxism. TMDs were more prevalent in girls. There was a significant sex difference (more among females) in the prevalence of painful TMDs. Conclusion: Posterior crossbite in the adolescent population analyzed may be related to TMDs, in contrary to deep-bite. The presence of posterior crossbite may have different impact on TMD findings between the sexes.

Self-report of temporomandibular joint clicking and psychological factors: is there an association?

The objectives of this study were to test the hypothesis that self-reported TMJ clicking sounds in adolescents are positively associated with non-specific somatic symptoms, self-perception of body image and care-seeking behaviour. A cross-sectional study was carried out in 353 young adolescents (48·4% females) recruited from community (N = 272) and orthodontic clinic (N = 81) settings. Assessments included self-reported TMJ clicking, non-specific physical symptoms, body image concerns and for the clinic sample only, the source of motivation for treatment. TMJ sounds were self-reported by 19% of the sample and were associated with higher scores for non-specific physical symptoms and body image concerns (P < 0·001). Adolescents who were self-motivated to seek orthodontic treatment had greater scores for non-specific physical symptoms, more body image concerns and tended to report TMJ sounds more often (26·3% and 7·7% respectively; P = 0·41) than those who were solely parent/family-motivated to seek treatment. Self-reported TMJ sounds in adolescents were associated with a propensity to somatisation and concerns with body image. Care-seeking adolescents have greater non-specific physical symptoms and body image concerns and tend to report more frequent TMJ sounds.

Assessment of risk factors for oro-facial pain and recent developments in classification: implications for management

Oro-facial pain research has during the last decades provided important novel insights into the basic underlying mechanisms, the need for standardised diagnostic procedures and classification systems, and multiple treatment options for successful rehabilitation of the patient in pain. Notwithstanding the significant progress in our knowledge spanning from molecules to chair, there may also be limitations in our ability to integrate and interpret the tremendous amount of new data and information, in particular in terms of the clinical implications and overriding conceptual models for oro-facial pain. The aim of the present narrative review is to briefly summarise some of the current thoughts on oro-facial pain mechanisms and recent attempts to identify biomarkers and risk factors leading to the proposal of a new risk assessment diagram for oro-facial pain (RADOP) and a provocative new concept based on stochastic variation between multiple risk factors. Finally, the implications for novel management strategies will briefly be discussed.

Features of occlusal state in female Japanese patients with migraine: a case-controlled study

OBJECTIVES

The prevalence rate of migraines is 8.4%; it is mostly diagnosed in women at 20s to 40s, and is known to cause major physical and mental disruption to daily life. This study was conducted on women aged between their 20s and 40s, in order to investigate the possible differences in the features of the occlusal state between a migraine and a non-migraine (control) group.

METHODS

Age-matched female patients with migraine (n = 60) diagnosed by headache specialists and healthy controls (n = 57) were enrolled. Dental casts were used to evaluate some features.

RESULTS

The maxillary and mandibular dentition casts from the migraine group showed significantly characteristic findings in their Angle's classification, overjet, and deviation in the anterior tooth midline, compared to the control group.

DISCUSSION

The results relating occlusal state to both tension-related headaches and migraines, which have different pathogeneses, suggest the possibility of dental intervention to improve the symptoms of primary headaches.

WITHDRAWN: Orthodontics for treating temporomandibular joint (TMJ) disorders

The Cochrane Oral Health Group withdrew this review as of Issue 1, 2016. The review is out of date and does not meet current Cochrane methodological standards. It will be superseded by a new Cochrane review on Occlusal interventions for managing temporomandibular disorders.

The editorial group responsible for this previously published document have withdrawn it from publication.

Do changes in oral health-related quality-of-life, facial pain and temporomandibular disorders correlate after treatment of severe malocclusion?

INTRODUCTION

The aim was to evaluate the relationships of changes in facial pain, temporomandibular disorders (TMDs) and oral health-related quality-of-life (OHRQoL) in adults who underwent orthodontic or orthodontic/surgical treatment.

METHODS

Sixty-four patients (46 women, 18 men, range 18-64 years) with severe malocclusion and functional problems were treated in Oulu University Hospital. Of these, 44 underwent orthodontic-surgical and 20 orthodontic treatment. Data were collected with questionnaires and clinical stomatognathic examinations before and on average 3 years after treatment. The OHRQoL was measured with OHIP-14 (The Oral Health Impact Profile), the intensity of facial pain with the Visual Analogue Scale (VAS) and the severity of TMD with the Helkimo's anamnestic (Ai) and clinical (Di) dysfunction indices.

RESULTS

A significant improvement was found in facial pain, signs and symptoms of TMD and OHRQoL after the treatment (p < 0.05). The decrease in VAS was associated with improvement in OHIP-14 severity (r = 0.296, p = 0.019). The correlations between changes in OHIP-14 severity and Ai and Di were not statistically significant.

CONCLUSION

Treatment of severe malocclusion seemed to improve OHRQoL via decreased facial pain. Decreased facial pain was associated especially with improved OHRQoL dimensions of physical pain, physical disability and social disability.

Outcome assessment of lingual and labial appliances compared with cephalometric analysis, peer assessment rating, and objective grading system in Angle Class II extraction cases

OBJECTIVE

To validate our hypothesis that there would be significant differences in treatment outcomes, including cephalometric values, degree of root resorption, occlusal indices, and functional aspect, between cases treated with labial and lingual appliances.

MATERIALS AND METHODS

Twenty-four consecutively treated Class II cases with extractions and lingual appliance were compared with 25 matched cases treated with extraction and labial appliance. Orthodontic treatment outcomes were evaluated by cephalometric analysis, peer assessment rating, and an objective grading system (OGS). Additionally, functional analysis was also performed in both groups after orthodontic treatment. Statistical comparison was performed using the Wilcoxon signed rank test within the groups, and the Mann-Whitney U-test was used to compare between the labial and lingual groups.

RESULTS

The only significant difference between the groups was that the interincisal angle was larger in the lingual group than in the labial group. OGS evaluation showed that control over root angulation was significantly worse in the lingual group than in the labial group. There was no significant difference between groups in the amount of root resorption or in functional evaluation.

CONCLUSIONS

Generally, lingual appliances offer comparable treatment results to those obtained with labial appliances. However, care should be taken with lingual appliances because they are more prone to produce uprighted incisors and root angulation.

Investigation of the Relationship between Increased Vertical Overlap with Minimum Horizontal Overlap and the Signs of Temporomandibular Disorders

PURPOSE

The purpose of this study was to test the null hypothesis that there was no relationship between increased vertical overlap (vertical overlap ≥4 mm) with minimal horizontal overlap (horizontal overlap ≤2 mm) and the signs of temporomandibular disorders.

MATERIALS AND METHODS

Thirty participants (20 women, aged 20 to 45 years) with increased vertical overlap and minimal horizontal overlap, and 30 participants (20 women, aged 20 to 45 years) with no contact between the anterior teeth (control group) were examined. Diagnoses, psychological status (depression and nonspesific physical symptoms), and chronic pain severity were judged according to the Research Diagnostic Criteria for Temporomandibular Disorders and then compared. For statistical analysis of quantitative data, along with the descriptive statistical methods (mean, standard deviation, frequency), Student's t-test was used to compare parameters that reflected a normal distribution. Comparison of qualitative data between groups was performed using Chi-square and Fisher's exact tests. The level of significance was set at p < 0.05.

RESULTS

In this study, deviation upon maximum opening was found significantly more frequently in the increased vertical overlap group than in the control group (p < 0.05). Tenderness upon palpation of lateral pterygoid muscles was observed more often in the increased vertical overlap group compared with the control group (p < 0.05). Opening-closing joint sounds occurred significantly more often in the increased vertical overlap group than in the control group (p = 0.050).

CONCLUSION

Within the limitations of this study, deviation upon maximum opening, tenderness of lateral pterygoid muscles (upon palpation), and opening-closing joint sounds occurred more often in the increased vertical overlap occlusions with minimum horizontal overlap compared to the control groups. These results indicated that clinicians should pay special attention to the tempormandibuar joint status of patients with significant vertical overlap anteriorly and position of the incisors when performing dental treatments that require reestablishment of incisor relationships.

Comparison of intrusion effects on maxillary incisors among mini implant anchorage, j-hook headgear and utility arch

BACKGROUND

Intrusion of maxillary incisors is one of the most important and difficult tooth movements to achieve as a part of orthodontic therapy. A variety of techniques were used in the past to intrude the maxillary incisors before the emergence of mini implants in Orthodontics. Mini implants are temporary anchorage devices used to produce various tooth movements. The research was carried out to evaluate and compare the efficiency of producing intrusion of maxillary incisors using mini implants, utility arch and j- hook headgear.

MATERIALS AND METHODS

The study was conducted on 30 subjects divided into 3 Groups equally. Group 1- mini implant anchorage, Group 2 - j- hooks headgear and Group 3- utility arch were used for intrusion of the maxillary incisors. Conventional lateral cephalograms were taken before treatment and at the end of intrusion. Five cephalometric parameters were used to measure the amount of intrusion attained in each Group. Intra Group comparisons were done using student t-test and inter Group comparisons were done using ANOVA The duration of intrusion was four months in all the three Groups.

RESULTS

In Group 1 the mean average intrusion attained was 2.1 mm, the mean average intrusion attained in Group 2 was 0.7 mm, and the mean average intrusion achieved in Group 3 was 1.4 mm with a side effect of 0.75 mm of molar extrusion.

CONCLUSION

Although, both mini implants and utility arch can be used to attain significant amounts of incisor intrusion but using mini implants will produce true intrusion without any other side effects.

Electromyographic analysis of masseter and temporal muscles, bite force, masticatory efficiency in medicated individuals with schizophrenia and mood disorders compared with healthy controls

This study aimed to comparatively analyse the electromyographic activity of the masseter and temporal muscles at rest and during mandible postural clinical conditions (right and left laterality, protrusion and maximum voluntary contraction), right and left maximum molar bite forces and the masticatory efficiency of individuals with schizophrenia or mood disorders - all medicated (medicated groups) compared with control group (healthy volunteers) via electromyography. Individuals were distributed into three groups: Group I (Schizophrenia - 20 individuals), Group II (mood disorders - 20 individuals) and Group III (Control - 40 individuals). Basically, the results were only statistically significant for the clinical mandible conditions and bite force. The most unsatisfactory results were observed in the medicated groups in relation to the control group. The group with mood disorders obtained the most unsatisfactory results compared with the group with schizophrenia. It was suggested by these observations that the association of mood disorders and schizophrenia with medication has negatively affected the stomatognathic system in relation to controls when the electromyography and bite force were used for the analysis.

[Does dental class II division 2 predispose to temporomandibular disorders?]

Because of its anatomical/physiological characteristics, the Class II division 2 (class II, div. 2) is one of the malocclusions considered as a possible risk factor for Temporomandibular disorders (TMD). A literature review was conducted from the electronic databases of Medline and Elsevier Masson, through the year 2010, in order to clarify the relationships that may exist between Class II division 2 and TMD. This research helped identify 50 articles: 7 articles specifically concerned the Class II div. 2, 37 articles concerned some of the characteristics of the Class II div. 2, considered individually (Class II, deep bite, retroclined maxillary incisors, mandibular retrognathism) and 6 articles orthodontic treatment. From the conclusions of these studies, the Class II, div. 2 does not appear to represent a significant risk factor for TMD. The clearest association would involve mandibular retrognathism and the risk of articular disk displacement. However, given the low number of articles published on this topic, the methodological variability and the contradictory results, it is difficult to identify reliable conclusions and, consequently, the therapeutic indications for the treatment of Class II div. 2 patients with TMD.

Establishing better biological models to understand occlusion. I: TM joint anatomic relationships

Belief in and rejection of a relationship of occlusion and temporomandibular joint (TMJ) condyle-fossa position with normal and abnormal function are still contentious issues. Clinical opinions can be strong, but support in most published data (mostly univariate) is problematic. Distribution overlap, low sensitivity and specificity are a common basis to reject any useful prediction value. Notwithstanding, a relationship of form with function is a basic tenet of biology. These are multifactor problems, but the questions mostly have not been analysed as such. This review moves the question forward by focusing on TM joint anatomic organisation as the multifactor system it is expected to be in a closed system like a synovial joint. Multifactor analysis allows the data to speak for itself and reduces bias. Classification tree analysis revealed useful prediction values and usable clinical models which are illustrated, backed up by stepwise logistic regression. Explained variance, R(2), predicting normals from pooled TMJ patients was 32·6%, sensitivity 67·9%, specificity 85·7%; 37% versus disc displacement with reduction; and 28·8% versus disc displacement without reduction. Significant osseous organisational differences between TM joints with clicking and locking suggest that this is not necessarily a single disease continuum. However, a subset of joints with clicking contained characteristics of joints with locking that might contribute to symptom progression versus resistance. Moderately strong models confirm there is a relationship between TMJ osseous organisation and function, but it should not be overstated. More than one model of normals and of TM derangement organisation is revealed. The implications to clinical decision-making are discussed.

Skeletal pattern in subjects with temporomandibular joint disorders

INTRODUCTION

To establish the skeletal pattern in subjects with malocclusions and temporomandibular disorders (TMD); to assess the relationship between craniofacial skeletal structures and TMD in subjects with malocclusions.

MATERIAL AND METHODS

Sixty-four subjects with malocclusions, over 18 years of age, were included in the study. Temporomandibular disorders were clinically assessed according to the Helkimo Anamnestic Index. Subjects underwent a lateral cephalogram. Subjects were grouped according to the sagittal skeletal pattern (ANB angle) into class I, II and III. Parametric Student tests with equal or unequal variations were used (variations were previously tested with Levene test).

RESULTS

Twenty-four patients with TMD (experimental sample); 40 patients without TMD (control group); interincisal angle was higher in class I and II (p < 0.05) experimental subjects; overjet was larger in experimental subjects; midline shift and Wits appraisal were broader in the experimental group in all three classes. In class III subjects, the SNB angle was higher in the experimental group (p = 0.01). Joint noises followed by reduced mandible mobility, muscular pain and temporomandibular joint (TMJ) pain were the most frequent symptoms in subjects with TMD and malocclusions.

CONCLUSIONS

Temporomandibular joint status is an important factor to consider when planning orthodontic treatment in patients with severe malocclusions; midline shift, large overjet and deep overbite have been associated with signs and symptoms of TMD.

A review of the oral health-related evidence that supports the orthodontic treatment need indices

BACKGROUND AND OBJECTIVES

To date, there is no evidence-based method of quantification for malocclusion. Consequently, how deviant occlusal traits should be scored and weighted relative to one another is a matter of serious debate. Orthodontic Treatment Need Indices (OTNI) use the subjective opinion of the experts, as their foundation, to define the pathological boundaries (cut-offs) of occlusal traits. This paper reviews the evidence relating malocclusions or deviated occlusal traits to oral health problems, and investigates if this evidence supports the cut-off points and the rationale used for OTNI.

MATERIALS AND METHODS

The relevant cited studies and reviews from the MEDLINE, Web of Science, Scopus, Cochrane databases, and scientific textbooks were used. The citation rate was confirmed by using the Google Scholar.

RESULTS

So far, the evidence for harmful effects of deviated occlusal traits on oral health is either lacking or exists as cross-sectional (mostly) and longitudinal (a few and primarily short-term) studies. When an association was reported between a deviated occlusal trait and an oral health problem, either the strength of that association was weak, or due to methodological issues, findings were not conclusive. Consequently, establishing a cause and effect relationship is difficult. Further, commonly used OTNI do not record a full spectrum of occlusal traits, and relating their ranking or scoring systems to the available evidence is difficult. Therefore, there is little evidence to suggest that individuals with a high need (high score), as measured by OTNI, will necessarily put at risk their oral health if they turn down orthodontic therapy.

CONCLUSION

OTNI have a role in the epidemiology and can be used for resource planning, but their predictive value to detect the future objective functional deficits or oral health problems is questionable. OTNI will need revalidation over time with emerging research findings.

Occlusal dysesthesia: a qualitative systematic review of the epidemiology, aetiology and management

Occlusal dysesthesia refers to a persistent complaint of uncomfortable bite sensation with no obvious occlusal discrepancy. This systematic review aimed to draw a picture of such patients, to present an agreement of previously reported diagnostic criteria and to analyse the evidence level of the recommended management approaches. An electronic search for all relevant reports on occlusal dysesthesia was thoroughly performed based on previous nomenclatures (e.g. phantom bite, occlusal hyperawareness) in PubMed and The Cochrane Library in July, 2011. A total of 84 reports were matched, among which only 11 studies were included after a two-step (abstract and detailed full-text revision) screening process. Additionally, a thorough manual review of reference lists of the included reports enabled the inclusion of two additional studies. Data analysis revealed that 37 occlusal dysesthesia patients presented a mean age of 51.7 ± 10.6 years and were predominantly women (male/female: 1/5.1) with symptom duration of more than 6 years (average: 6.3 ± 7.5 years) and with concomitant psychological disturbances (e.g. mood disorders, somatoform disorders, personality disorders). Only four authors presented diagnostic criteria for occlusal dysesthesia, which served as the basis for an agreement in the diagnostic criteria. Treatment approaches included psychotherapy, cognitive/behaviour therapy, splint therapy and prescription of anti-depressants or anti-anxiety drugs. Classification of evidence level of management approaches, however, revealed that most of them were expert opinions with single- or multiple-case report(s). Future studies are necessary for a deeper understanding of the mechanisms behind the occlusal dysesthesia symptoms, and consequently, for improvements in evidence-based management approaches.

Persistent orofacial muscle pain

The pathophysiology of persistent orofacial myalgia has been the centre of much controversy. In this article we suggest a novel descriptive term; 'persistent orofacial muscle pain' (POMP) and review current evidence that supports the hypothesis that the induction of POMP involves the interplay between a peripheral nociceptive source in muscle, a faulty central nervous system component and decreased coping ability. In this context it is widely accepted that a complex interaction of variable intrinsic and extrinsic factors act to induce POMP and dysfunction.

Masseter length determines muscle spindle reflex excitability during jaw-closing movements

INTRODUCTION

The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns.

METHODS

Twenty-eight adult volunteers (16 women; ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif; and Mona Lisa, Canberra, Australia).

RESULTS

Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008).

CONCLUSIONS

These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses.

Assessment of the effect of the use of laser light or dantrolene on facial muscle under occlusal wear: a Raman spectroscopic study in a rodent model

OBJECTIVE

The aim of the present study was to use Raman spectroscopy to measure levels of CaPi in muscles under occlusal wear and treated with laser phototherapy (LPT) or muscle-relaxant therapy or both on rodents.

BACKGROUND

The etiology of temporomandibular disorders is multifactorial. Malocclusion may influence the masticatory muscles, causing fatigue. A major type of fatigue is the metabolic, caused by the increased accumulation of metabolites such as inorganic phosphate. Raman spectroscopy allows nondestructive analysis of the biochemical composition of tissues.

METHODS

The 30 male Wistar rats were randomly divided into three groups: occlusal wear (G-1), occlusal wear + LPT (G-2), and occlusal wear + muscle relaxant (G-3). Ten untreated animals were used for baseline data. Under intraperitoneal general anesthesia, animals of groups 1, 2, and 3 had unilateral amputation of molar cusps to simulate an occlusal-wear situation. The masseter muscle of G-2 received LPT (lambda830 nm, 4 J/cm(2), 40 mW, phi approximately 2 mm) after the procedure and repeated every other day for 14-30 days. Animals of G-3 were treated with a daily injection of dantrolene (2.5 mg/kg in 0.5 ml of H(2)O) beginning 24 h after cusp removal. Animals were killed with an overdose of general anesthetics at days 14 and 30 after cusps removal, and the ipsilateral masseter muscle was excised and divided into two parts. One part was routinely processed and underwent histologic analysis; the other was kept in liquid nitrogen for Raman spectroscopy. The mean value of the intensity of the peak 958 per centimeter was determined.

RESULTS

No morphologic changes were seen. Raman analysis showed significantly less Raman intensity in the laser group at 30 days (p < 0.01).

CONCLUSION

Occlusal wear did not caused morphologic alterations in the masseter muscle but resulted in changes of the levels of CaP(i) that were less compromising when the laser light was used.

Orthodontics for treating temporomandibular joint (TMJ) disorders

BACKGROUND

Temporomandibular disorders (TMD) relate to discomfort of the temporomandibular joint (TMJ). The disorder is multifactorial with a degree of psychogenic influence varying throughout an individual's life with phases of symptoms affecting the quality of life. In an attempt to treat this complex group of disorders many treatment modalities have been identified some of which are also considered in other Cochrane reviews. The disorder also has a normal cycle of events appearing to spontaneously improve without treatment.

OBJECTIVES

To establish the effectiveness of orthodontic intervention in reducing symptoms in patients with TMD (compared with any control group receiving no treatment, placebo treatment or reassurance) and to establish if active orthodontic intervention leads to TMD.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching of orthodontic journals and other related journals was undertaken in keeping with the Cochrane Collaboration handsearching programme. No language restrictions were applied. Authors of any studies were identified, as were experts offering legal advice, and contacted to identify unpublished trials. Most recent search: 13th April 2010.

SELECTION CRITERIA

All randomised controlled trials (RCTs) including quasi-randomised trials assessing orthodontic treatment for TMD were included. Studies with adults aged equal to or above 18 years old with clinically diagnosed TMD were included. There were no age restrictions for prevention trials provided the follow-up period extended into adulthood. The inclusion criteria required reports to state their diagnostic criteria for TMD at the start of treatment and for participants to exhibit two or more of the signs and/or symptoms. The treatment group included treatment with appliances that could induce stable orthodontic tooth movement. Patients receiving splints for 8 to 12 weeks and studies involving surgical intervention (direct exploration/surgery of the joint and/or orthognathic surgery to correct an abnormality of the underlying skeletal pattern) were excluded. The outcomes were: how well were the symptoms reduced, adverse effects on oral health and quality of life.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in triplicate and independently by three review authors. As no two studies compared the same treatment strategies (interventions) it was not possible to combine the results of any studies.

MAIN RESULTS

The searches identified 284 records from all databases. Initial screening of the abstracts and titles by all review authors identified 55 articles which related to orthodontic treatment and TMD. The full articles were then retrieved and of these articles only four demonstrated any data that might be of value with respect to TMD and orthodontics. After further analysis of the full texts of the four studies identified, none of the retrieved studies met the inclusion criteria and all were excluded from this review.

AUTHORS' CONCLUSIONS

There are insufficient research data on which to base our clinical practice on the relationship of active orthodontic intervention and TMD. There is an urgent need for high quality randomised controlled trials in this area of orthodontic practice.When considering consent for patients it is essential to reflect the seemingly random development/alleviation of TMD signs and symptoms.