The aim of the present investigation was to perform a systematic review of the literature dealing with the issue of sleep bruxism prevalence in children at the general population level. Quality assessment of the reviewed papers was performed to identify flaws in the external and internal validity. Cut-off criteria for an acceptable external validity were established to select studies for the discussion of prevalence data. A total of 22 publications were included in the review, most of which had methodological problems limiting their external validity. Prevalence data extraction was performed only on eight papers that were consistent as for the sampling strategy and showed only minor external validity problems, but they had some common internal validity flaws related with the definition of sleep bruxism measures. All the selected papers based sleep bruxism diagnosis on proxy reports by the parents, and no epidemiological data were available from studies adopting other diagnostic strategies (e.g. polysomnography or electromyography). The reported prevalence was highly variable between the studies (3·5-40·6%), with a commonly described decrease with age and no gender differences. A very high variability in sleep bruxism prevalence in children was found, due to the different age groups under investigation and the different frequencies of self-reported sleep bruxism. This prevented from supporting any reliable estimates of the prevalence of sleep bruxism in children.

The aim of the present study was to compare the personality pattern, the anxiety level and the temporomandibular disorders (TMD) between bruxist and non-bruxist children with mixed dentition. Fifty-two subjects, with a mean age of 9.45 years (range 8-11) were evaluated and classified as bruxist (n = 26), according to the American Academy of Sleep Medicine (AASM) and the presence of dental wear clinically visible, under the same conditions of artificial light and position. The control children (n = 26) did not present dental wear and did not accomplished all the AASM criteria. The personality pattern and the anxiety of the bruxist children were studied by means of the Children's Personality Questionnaire (CPQ) and the Conners' Parents Rating Scales (CPRS), respectively, and compared with the personality traits and the anxiety level of a non-bruxist population. The TMD were also evaluated using the Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD) criteria. The data were analysed with the student's t-test, Fisher's exact test and chi-squared tests. A multivariated analysis was performed using a logistic regression with the stepwise likelihood ratio method. Compared with the controls, the bruxist children had significantly higher tension personality and were more anxiety prone. The bruxist children presented more TMD-related signs and symptoms than children in the control group. A strong correlation was found among bruxism, TMD, the high anxiety level and the high tension personality trait.

Four main causes of bruxism have been studied - high anxiety level, malocclusion, temporomandibular disorders (TMD) and oral habits. Effective dental treatment for this problem is unknown in children with primary teeth, although, high prevalence has been reported. The aim of this study was to investigate the effectiveness of psychological techniques in children with bruxism. A total of 33 children, 3-6 years of age with normal occlusal features, without oral habits, rate in the Conners' parent rating scales (CPRS) and more than 0.75% in Conners' teacher rating scales (CTRS), and one or more temporomandibular joint (TMJ) disorders registered in the Bernal and Tsamtsouris examination, were selected from 188 children. Two psychological techniques, 'directed muscular relaxation' and 'competence reaction', were applied for 6 months. The results were analysed with a Wilcoxon rank sum test. All patients reduced their anxiety level and TMJ disorders, with statistical significance (P < 0.05). The psychological techniques were effective in the reduction of signs of bruxism in children with primary teeth.

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How bruxism develops from adolescence to early adulthood remains unclear. A previous database was revisited to evaluate the natural course of self-reported tooth grinding and clenching among young Finns aged 14-23 using four assessments. Overall, the self-reported frequencies of both grinding and clenching increased during the examination period: from 13.7% to 21.7% and from 9.2% to 14.8%, respectively. There were significant increases (without a statistically significant difference between genders) in both grinding (P = 0.002) and clenching (P = 0.015) between 15 and 23 years. A significant rise in grinding between 18 and 23 years was also found (P = 0.011). It is concluded that self-reported bruxism increases from adolescence to young adulthood. Moreover, there are large differences between individuals, and fluctuations may occur in the natural course of bruxism.

Bruxism seems to be related to altered natural head posture and more intense dental wear. Further studies are necessary to explore bruxism mechanisms.

Class II skeletal malocclusion and respiratory disorders owing to the obstruction of the upper airway at early growth stages have been correlated. The retro/micrognathism can be treated with functional appliances. However, the effects of an early functional orthopedic treatment on the airway dimensions have not been evaluated before the growth peak. Therefore, the objective of this study was to evaluate the changes in the airway dimensions of class II retrognathic children who received treatment with either Klammt or Bionator on a pre-pubertal stage. The sample consisted of 50 lateral cephalograms of class II retrognathic patients in a pre-puberal stage, before and after the use of a Klammt or Bionator II treatment for 1 year. The data were evaluated by Student's t-test or Mann-Whitney test, and significance was set at 5% (P < 0·05). When the measurements before and after treatment were compared, a statistically significant increase in the airway dimensions was found at the space where the adenoid tissue was located. The only airway dimensions that increased after treatment with functional appliances were the ones located at the nasopharynx. The adenoid tissue is still in the peak of growing at the ages of the subjects included in this study. However, the measurements along the nasopharynx increased when compared with the initial ones. Still, similar retrospective and prospective studies are needed at older stages.