Ambrosina Michelotti

Postural stability and unilateral posterior crossbite : Is there a relationship?

The aim of this study was to test the hypothesis that unilateral posterior crossbite influences postural stability of the whole body. Twenty-six subjects (14 males and 12 females) affected with unilateral posterior crossbite were selected and compared with 52 controls matched for age and gender. Postural stability was assessed using a stabilometric platform. The following stabilometric measurements were assessed: weight distribution on foot area and speed of body sway. Tests were performed under two occlusal conditions: teeth in intercuspal position (ICP) and while keeping two cotton rolls between teeth without clenching. The weight distribution on foot area and the speed of body sway were not significantly influenced from crossbite (with and without lateral mandibular slide), occlusal conditions (ICP, cotton rolls), and gender. Therefore, the treatment of this malocclusion in order to prevent or to treat postural disorders is not justified.

Catechol-O-methyltransferase (COMT) gene polymorphisms as risk factor in temporomandibular disorders patients from Southern Italy.

Objectives:To evaluate the role of COMT gene variants as potential risk factors in a group of patients affected with chronic temporomandibular disorder (TMD) pain. Methods:We sequenced COMT gene in 182 Italian subjects (50 affected by TMD and 132 controls). The study population consisted of patients affected by myogenous and/or arthrogenous pain (RDC/TMD: Ia, Ib, IIIa, IIIb diagnostic categories). Results:We detected 40 single nucleotide polymorphisms (SNPs) variants (18 novel). Three SNPs, all located in the promoter regions, were more frequently present in cases than in controls (rs 4646310 P=0.018, rs165656 P=0.001, rs 165722 P=0.007). After the False Discovery Rate (FDR) correction rs165656 remained significantly associated with TMD (P=0.049). In addition, the rs 4646310 (AG vs GG, P=0.015) and rs 165656 (GG vs CC, P=0.001) were at binary logistic regression analysis independently associated with TMD, conferring a risk disease of 2.6 (CI= 1.2-5.6) and of 5.3 (CI= 2.0-13.7) respectively. Discussion:Our data extend the number of SNPs present in the promoter region that could play a regulatory role in COMT gene and suggest that the genetic polymorphisms rs 165656 and rs 4646310 exert a role in TMD susceptibility.

Next steps in development of the diagnostic criteria for temporomandibular disorders (DC/TMD): Recommendations from the International RDC/TMD Consortium Network workshop

The development of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) (1) involved expanding the taxonomy for all TMDs (2) in order to propose for future validation DC for empirically ...

The effect of culture on pain sensitivity

Cross-cultural differences in pain sensitivity have been identified in pain-free subjects as well as in chronic pain patients. The aim was to assess the impact of culture on psychophysical measures using mechanical and electrical stimuli in patients with temporomandibular disorder (TMD) pain and pain-free matched controls in three cultures. This case-control study compared 122 female cases of chronic TMD pain (39 Saudis, 41 Swedes and 42 Italians) with equal numbers of age- and gender-matched TMD-free controls. Pressure pain threshold (PPT) and tolerance (PPTo) were measured over one hand and two masticatory muscles. Electrical perception threshold and electrical pain threshold (EPT) and tolerance (EPTo) were recorded between the thumb and index fingers. Italian females reported significantly lower PPT in the masseter muscle than other cultures (P < 0.001) and in the temporalis muscle than Saudis (P = 0.003). Swedes reported significantly higher PPT in the thenar muscle than other cultures (P = 0.017). Italians reported significantly lower PPTo in all muscles than Swedes (P ≤ 0.006) and in the masseter muscle than Saudis (P < 0.001). Italians reported significantly lower EPTo than other cultures (P = 0.01). Temporomandibular disorder cases, compared to TMD-free controls, reported lower PPT and PPTo in all the three muscles (P < 0.001). This study found cultural differences between groups in the PPT, PPTo and EPTo. Overall, Italian females reported the highest sensitivity to both mechanical and electrical stimulation, while Swedes reported the lowest sensitivity. Mechanical pain thresholds differed more across cultures than did electrical pain thresholds. Cultural factors may influence response to type of pain test.

The relationship between molar dentoalveolar and craniofacial heights

Excessive vertical growth of the posterior dentoalveolar region has been implicated in the etiology of the so-called long-face syndrome. In this study, we tested the hypothesis that molar dentoalveolar heights are positively related to vertical craniofacial features. Cephalometric measurements obtained from 82 adult subjects were entered as independent variables in a multiple regression model. Maxillary and mandibular molar dentoalveolar heights were entered as dependent variables. Approximately 70% of the total variance was explained by anterior lower facial height (ANS-Me) and the mandibular palatal plane angle (PP-MP). Increases of ANS-Me and PP-MP had opposite effects on the amount of molar dentoalveolar heights. The lowest values of molar dentoalveolar heights were found in subjects with a small ANS-Me distance but with a wide PP-MP angle. The findings suggest that individuals with a marked divergence of the jaws may also have a reduced molar dentoalveolar vertical development.

Incidence of temporomandibular joint clicking in adolescents with and without unilateral posterior cross‐bite: a 10‐year follow‐up study

Among different malocclusions, posterior cross-bite is thought to have a strong impact on the correct functioning of the masticatory system. The association between unilateral posterior cross-bite (UPCB) and temporomandibular joint (TMJ) clicking, however, remains still controversial. The aim of this study was to investigate whether the presence of UCPB during early adolescence increases the risk of reporting TMJ clicking after a long-term follow-up. A longitudinal survey design was carried out in a group of 12-year-old young adolescents, who were examined at baseline for TMJ clicking sounds and unilateral posterior cross-bite. After 10 years, 519 subjects could be reached by a telephone survey. Standardised questions were used to collect self-reported TMJ sounds and to determine whether participants had received an orthodontic treatment. Logistic regression analysis revealed a significant association between unilateral posterior cross-bite and subjectively reported TMJ clicking (odds ratio = 6·0; 95% confidence limits = 3·4-10·8; P < 0·0001). The incidence of TMJ clicking was 12%. At a ten-year follow-up, self-reports of TMJ clicking were significantly associated with the presence of UPCB at baseline, but not with the report of having received an orthodontic treatment. Within the limitation of this study, the presence of unilateral posterior cross-bite in young adolescents may increase the risk of reporting TMJ sounds at a 10-year follow-up. The provision of an orthodontic treatment, however, does not appear to reduce the risk of reporting TMJ sounds.

Effect of somatosensory amplification and trait anxiety on experimentally induced orthodontic pain.

The perception of pain varies considerably across individuals and is affected by psychological traits. This study aimed to investigate the combined effects of somatosensory amplification and trait anxiety on orthodontic pain. Five-hundred and five adults completed the State Trait Anxiety Inventory (STAI) and the Somatosensory Amplification Scale (SSAS). Individuals with combined STAI and SSAS scores below the 20th percentile (LASA group: five men and 12 women; mean age ± SD = 22.4 ± 1.3 yr) or above the 80th percentile (HASA group: 13 men and seven women; mean age ± SD = 23.7 ± 1.0 yr) were selected and filled in the Oral Behaviors Checklist (OBC). Orthodontic separators were placed for 5 d in order to induce experimental pain. Visual analog scales (VAS) were administered to collect ratings for occlusal discomfort, pain, and perceived stress. Pressure pain thresholds (PPT) were measured. A mixed regression model was used to evaluate pain and discomfort ratings over the 5-d duration of the study. At baseline, the LASA group had statistically significantly higher PPT values for the masseter muscle than did the HASA group. During the experimental procedure, the HASA group had statistically significantly higher discomfort and pain. A significant difference in pain ratings during the 5 d of the study was found for subjects in the HASA group. Higher OBC values were statistically significantly positively associated with pain. Somatosensory amplification and trait anxiety substantially affect experimentally induced orthodontic pain.

Short-Term Sensorimotor Effects of Experimental Occlusal Interferences on the Wake-Time Masseter Muscle Activity of Females with Masticatory Muscle Pain

AIMS To investigate the effects of the application of an acute alteration of the occlusion (ie, interference) on the habitual masseter electromyographic (EMG) activity of females with temporomandibular disorders (TMD)-related muscular pain during wakefulness. METHODS Seven female volunteers with masticatory myofascial pain participated in a crossover randomized clinical trial. Gold foils were glued on an occlusal contact area (active occlusal interference, AI) or on the vestibular surface of the same molar (dummy interference, DI) and left for 8 days. The masseter electromyogram was recorded during wakefulness in the natural environment by portable recorders under interference-free, dummy-interference, and active-interference conditions. The number, amplitude, and duration of EMG signal fractions with amplitudes above 10% of the maximum voluntary contraction (activity periods, APs) were computed in all experimental conditions. Muscle pain, headache, and perceived stress were each assessed with a visual analog scale (VAS), and an algometer was used to assess masseter and temporalis pressure pain thresholds. Data were analyzed by means of analysis of variance. RESULTS The frequency and duration of the recorded APs did not differ significantly between the experimental conditions (P>.05), but a small and significant reduction of the EMG mean amplitude of the APs occurred with AI (P<.05). Neither the VAS scores for muscular pain, headache, and perceived stress nor the pressure pain thresholds changed significantly throughout the entire experiment (P>.05). CONCLUSION An active occlusal interference in female volunteers with masticatory muscle pain had little influence on the masseter EMG activity pattern during wakefulness and did not affect the pressure tenderness of the masseter and temporalis.

Social impairment of individuals suffering from different types of chronic orofacial pain

BackgroundThe daily life of patients suffering from orofacial pain is considerably impaired as compared to healthy subjects. The aim of this study was to investigate the influence of different categories of orofacial pain on the habitual life of adult individuals.MethodsSeven hundred eighty-one individuals with orofacial pain were recruited from an initial sample of 1,058 patients. All the individuals were allocated to groups according to their diagnosis: myofascial pain (group A, 676 subjects, 525 females and 151 males; mean age ± SD = 35.2 ± 12.6), migraine (group B, 39 subjects, 29 females and 10 males; mean age ± SD 36.0 ± 10.7), and both myofascial pain and migraine (group C, 66 subjects, 56 females and 10 males, mean age ± SD = 35.6 ± 10.8). Characteristic pain intensity (CPI), disability days (DD), disability score (DS), and graded chronic pain intensity (GCPS) were calculated according to Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis II. Depression and somatization (nonspecific physical symptoms) scores were also calculated.ResultsA significant association between groups and GCPS categories was found (p < 0.0001). Post hoc tests showed a significant difference between groups A and B and between A and C, but not between B and C. In group A, the most frequent GCPS score was grade II. The most frequent GCPS score in groups B and C was grade III, indicating a moderate limiting impairment. This score was more frequent in group B (41%) than in the other groups (group A = 20.6%, group C = 34.8%). GCPS grade IV was more frequent in group C (19.7%) than in the other groups. Group C had significantly higher scores for nonspecific physical symptoms than group A (p < 0.05).ConclusionsMyofascial pain and migraine sensibly affect the common daily life of adult individuals. The comorbidity of both conditions determines a major impairment.

Dental and skeletal effects of palatal expansion techniques: a systematic review of the current evidence from systematic reviews and meta-analyses

The aim was to assess the quality and to summarise the findings of the Systematic Reviews (SRs) and Meta-Analyses (MAs) on the dental and skeletal effects of maxillary expansion. Electronic and manual searches have been independently conducted by two investigators, up to February 2015. SRs and MAs on the dentoalveolar and skeletal effects of fixed expanders were included. The methodological quality was assessed using the AMSTAR (A Measurement Tool to Assess Systematic Reviews). The design of the primary studies included in each SR/MA was assessed with the LRD (Level of Research Design scoring). The evidence for each outcome was rated applying a pre-determined scale. Twelve SRs/MAs were included. The AMSTAR scores ranged from 4 to 10. Two SRs/MAs included only RCTs. The current findings from SRs/MAs support with high evidence a significant increase in the short-term of maxillary dentoalveolar transversal dimensions after Rapid Maxillary Expansion (RME). The same effect is reported with moderate evidence after Slow Maxillary Expansion (SME). However, there is moderate evidence of a non-significant difference between the two expansion modalities concerning the short-term dentoalveolar effects. With both RME and SME, significant increase of skeletal transversal dimension in the short-term is reported, and the skeletal expansion is always smaller than the dentoalveolar. Even though dental relapse to some extent is present, long-term results of the dentoalveolar effects show an increase of the transversal dimension, supported by moderate evidence for RME and low evidence for SME. Skeletal long-term effects are reported only with RME, supported by very low evidence.