Occlusal traits and longitudinal dental changes in children and adolescents with congenital or childhood onset myotonic dystrophy.

BACKGROUND/OBJECTIVES: This research aimed to study the malocclusions of children and adolescents with myotonic dystrophy type 1 (DM1), in respect to healthy individuals, and trace the occlusal changes that occurred in these individuals during growth. MATERIALS/METHODS: Thirty-six dental casts, from children and adolescents with DM1 living in western and southern Sweden, were compared with a control group of 50 healthy individuals. To identify potential changes in occlusal traits, 26 casts were assessed and followed-up over a median time of 9 years. Independent samples t-tests were used to compare the two groups and their changes over time. Paired samples t-tests tested changes over time within each group (P < 0.05). RESULTS: DM1 patients had a higher prevalence of anterior open bite, posterior crossbite, and Class III malocclusions. When compared to controls, patients presented smaller upper and lower intermolar as well as intercanine widths. In both groups, the individuals revealed longitudinal changes with a decrease in both upper and lower arch lengths and an increase on the palatal vault height. During the follow-up period, the prevalence of malocclusions remained almost the same, only significantly differing regarding the changes that occurred between groups referred to the upper intermolar width, which decreased among DM1 patients. CONCLUSIONS/IMPLICATIONS: In comparison to healthy controls, children and adolescents with DM1 have shown already at an early age a higher prevalence of both anterior open bite and posterior crossbite. These occlusal traits did not change with time apart from the upper narrow intermolar width, which further decreased with time.

Craniofacial morphology and growth in young patients with congenital or childhood onset myotonic dystrophy.

Background/objectives: This study investigated the craniofacial morphology of young individuals with congenital or childhood onset myotonic dystrophy type 1 (DM1) compared to healthy subjects. The study also followed growth changes in their facial morphology over a 5-year period. Materials/methods: Lateral cephalograms of the 26 subjects (young patients with DM1 from west and south Sweden) were taken at baseline and after a 5-year period. These radiographs were compared with normal standards based on healthy individuals from the Michigan Growth Study, according to their age and sex, using paired t-tests (P < 0.05). Results: On examination of initial radiographic measurements, patients with DM1 showed, in the sagittal plane, larger ANB and smaller SNPg angles. Analysis of the vertical plane showed the mandibular plane angle (ML-NSL) and the intermaxillary angle (ML-NL) to be larger. During the 5-year follow-up period, the intermaxillary angle (ML-NL) remained the same in the group with DM1 whereas this angle decreased in healthy individuals. Limitations: For ethical reasons, historical cephalometric norms were used to compare the growth and the craniofacial morphology of patients with DM1. Conclusions/implications: Young patients with DM1 had already from the beginning a more retrognathic profile and hyperdivergent skeletal aberration with a steep mandibular plane and large intermaxillary angle when compared with healthy individuals. The intermaxillary angle did not decrease during the observation period, contrary to what was observed in healthy individuals.

Oral hygiene aspects in a study of children and young adults with the congenital and childhood forms of myotonic dystrophy type 1.

The primary aim was to study the interaction between oral hygiene, oral care, saliva production, and oral motor function in individuals with myotonic dystrophy type 1 (DM1). A secondary aim was to study how oral hygiene, oral care, and saliva flow rate are affected by gender, age, and subgroup of DM1 in this study population. The study comprised 52 individuals, seven to 29 years of age, divided into two subgroups of DM1, the congenital (N = 24) and childhood-onset forms (N = 28). A combined dental and oral motor examination was performed and the participants or caregivers answered a questionnaire with questions about general health and disabilities, medication, dental care, and oral health. Sixteen individuals with a plaque-, gingivitis-, or calculus-index score of 5-6 were considered to have poor oral hygiene. There were no significant differences between subgroups (age, gender, or form of DM1) in terms of the occurrence of calculus, gingivitis, plaque, or saliva flow rate. The mean value of the unstimulated whole saliva flow rate was 0.7(±0.44) mL/min. An open mouth at rest and oral motor dysfunction were frequent findings. The majority of Swedish children and young adults with the congenital or childhood form of DM1 have fair or poor oral hygiene, with a high occurrence of plaque and gingivitis. As a group, individuals with DM1 and poor oral hygiene have a higher frequency of caries and they report less satisfaction with their oral care at home and the quality of dental care received compared with those with good oral hygiene.

On oral health in children and adults with myotonic dystrophy.

BACKGROUND: Myotonic Dystrophy type 1 (DM1) is a hereditary neuromuscular multisystem disease with varying clinical expressions and severity. The prevalence worldwide is 5-20/100 000. It is characterized by progressive muscular waste and myotonia. Facial weakness is one of the earliest and most constant features. Muscular weakness has been shown to have an impact on oral health in various ways. The molecular basis for DM1 is an unstable trinucleotide (CTG) expansion on chromosome 19. The severity of the disease and time of onset is roughly correlated to the length of the CTG expansion. AIM: The overall aim of this thesis is to shed light on oral health with focus on periodontal disease and caries in adults and children with DM1. Specific aims are: 1) To assess oral health and motoric ability in adults with DM. 2) To explore caries related factors including oral sugar clearance. 3) To assess oral health and dental care in children with DM1 and to evaluate the changes observed longitudinally over a four year period. SUBJECTS AND METHODS In all, 27 adults, ages 35-64 years and 56 children, ages 2.7-18 years, and age and gender matched control persons were examined. Thirty-six of the children with DM and 33 of the control children were examined on two occasions about four years apart. Plaque, gingivitis caries and number of teeth were recorded. In the adult patients, finger force, oral muscular coordination ability, salivary secretion rate and oral sugar clearance were determined. In children, the ability to cooperate during dental treatment was estimated. Questionnaires concerning eating habits and dental care were also used. RESULT: The adult and children DM1 patients had significantly more caries, plaque and gingivitis and had lost more permanent teeth than the control patients. This was particularly evident for the boys with DM1. Motoric ability, salivary secretion and oral sugar clearance showed less favorable mean values for the adult DM group than for the control group. A negative correlation was found between plaque index and finger force. The children with DM1 had a lower ability to cooperate than the controls and general sedation was often needed during dental treatment. CONCLUSIONS: Adults and children with DM1 have more plaque, gingivitis and caries and have lost more teeth than age and gender-matched control persons. This may be explained by lower motoric ability, lower salivary secretion and slower oral sugar clearance and, in children, more cooperation problems. The differences between the groups remained or increased for children with DM1 over the four years in the longitudinal study. For these reasons, intensified prophylactic care, including easy home-care methods, is essential for patients with DM1 to firstly improve their oral health and secondly accustom DM1 children to the dental clinic and the treatment there.

Oral health status in a group of children and adolescents with myotonic dystrophy type 1 over a 4-year period.

AIM: The aim of this longitudinal study was to evaluate changes in oral health, orofacial function, and dental care in children with myotonic dystrophy type 1 (DM1) in comparison with a control group. METHODS: Thirty-six DM1 patients and 33 control patients out of originally 37 in each group were examined on two occasions about 4 years apart. Caries, plaque, and gingivitis were registered, mouth opening capacity assessed and the ability to cooperate in dental treatment estimated. Questionnaires concerning different aspects of oral health and care, symptoms of temporomandibular dysfunction (TMD), and dental trauma were also used. RESULTS: The DM1-patients, in particular the boys, had significantly more caries, plaque, and gingivitis than the control patients on both occasions and the increase in decayed missing or filled permanent teeth (DMFT) and surfaces (DMFS) was significantly larger. They received more dental care and had lower cooperation ability. Mouth opening capacity and increase of it was significantly lower and symptoms of TMD were significantly more frequent. CONCLUSIONS: DM1 patients, as they grow older, have increasing amounts of plaque and risk of caries and gingivitis. They have more TMD problems. Behaviour management problems do not seem to decrease with age. Increased prophylactic care is essential for DM1 patients.

Oral health in children and adolescents with myotonic dystrophy.

Myotonic dystrophy or dystrophia myotonica (DM) is a hereditary neuromuscular multisystem disease with a varying clinical expressivity and severity. The objective of this study was to assess the oral health in children with myotonic dystrophy and to compare it with a control group. Fifty-six DM patients, aged 2.7-18.0 yr, were compared with age- and gender-matched control patients with respect to caries, plaque, and gingivitis. Oral function and signs of temporomandibular dysfunction (TMD) were assessed, and the ability to co-operate in dental treatment was estimated. Questionnaires concerning eating habits, dental care, traumatic injuries to teeth, and orofacial function were also used. The DM patients had significantly more caries, plaque, and gingivitis than did control patients. They had more TMD problems and lower co-operation ability than the healthy control persons. General sedation was frequently needed to carry through dental treatment. DM patients are at risk of caries, gingivitis and TMD problems, and need intensified prophylactic care. Behavior management problems are common.

Long-term effects of chronic nicotine exposure on brain nicotinic receptors.

Chronic nicotine exposure results in long-term homeostatic regulation of nicotinic acetylcholine receptors (nAChRs) that play a key role in the adaptative cellular processes leading to addiction. However, the relative contribution of the different nAChR subunits in this process is unclear. Using genetically modified mice and pharmacological manipulations, we provide behavioral, electrophysiological, and pharmacological evidence for a long-term mechanism by which chronic nicotine triggers opposing processes differentially mediated by beta2*- vs. alpha7*nAChRs. These data offer previously undescribed insights into the understanding of nicotine addiction and the treatment of several human pathologies by nicotine-like agents chronically acting on beta2*- or alpha7*nAChRs.

Orofacial dysfunction in children and adolescents with myotonic dystrophy.

Myotonic dystrophy (DM) is a neuromuscular disorder caused by an expansion of a CTG repeat sequence on chromosome 19q13. The aim of the present study was to describe the characteristics and prevalence of oral motor dysfunction in a cohort of children and adolescents with DM and to correlate different aspects of oral motor function with the type of DM and sex. Fifty-six individuals with DM (30 males, 26 females; median age 13y 2mo; range 2y 6mo-21y 5mo) were compared with healthy controls. They were divided into four subgroups: severe congenital DM (n=18); mild congenital DM (n=18); childhood DM (n=18); and classical DM (n=2). A speech-language pathologist assessed different variables of oral motor function, intelligibility, and lip force. The families used a questionnaire to report on eating difficulties and drooling. All individuals with DM had impaired facial expression. Intelligibility was moderately or severely reduced in 30 patients (60%), excluding six patients without speech. Most had a moderate or severe impairment of lip motility (76.0%), tongue motility (52.2%), and lip force (69.2%), causing deviant production of bilabial and dental consonants. The families reported problems with eating (51.9%) and drooling (37.0%). Oral motor dysfunction was most prominent in congenital DM, and males were more affected than females.

Hierarchical control of dopamine neuron-firing patterns by nicotinic receptors.

Nicotine elicits dopamine release by stimulating nicotinic acetylcholine receptors (nAChRs) on dopaminergic neurons. However, a modulation of these neurons by endogenous acetylcholine has not been described. We recorded, in vivo, the spontaneous activity of dopaminergic neurons in the VTA of anaesthetized wt and nAChR knockout mice and their response to nicotine injections. Deleting alpha7 or beta2 subunits modified the spontaneous firing patterns, demonstrating their direct stimulation by endogenous acetylcholine. Quantitative analysis further revealed four principal modes of firing, each depending on the expression of particular nAChR subunits and presenting unique responses to nicotine. The prominent role of the beta2 subunit was further confirmed by its selective lentiviral reexpression in the VTA. These data suggest a hierarchical control of dopaminergic neuron firing patterns by nAChRs: activation of beta2*-nAChR switches cells from a resting to an excited state, whereas activation of alpha7*-nAChRs finely tunes the latter state but only once beta2*-nAChRs have been activated.

Dual effects of nicotine on dopamine neurons mediated by different nicotinic receptor subtypes.

Burst firing of dopaminergic neurons has been found to represent a particularly effective means of increasing dopamine release in terminal areas as well as activating immediate early genes in dopaminoceptive cells. Spontaneous burst firing is largely controlled by the level of activation of NMDA receptors in the ventral tegmental area (VTA) as a consequence of glutamate released from afferents arising mainly in the prefrontal cortex. Nicotine has been found to effectively increase burst firing of dopaminergic cells. This effect of nicotine may be due to an alpha 7 nicotinic receptor-mediated presynaptic facilitation of glutamate release in the VTA. By the use of in-vivo single-cell recordings and immunohistochemistry we here evaluated the role of alpha 7 nicotinic receptors in nicotine-induced burst firing of dopamine cells in the VTA and the subsequent activation of immediate early genes in dopaminoceptive target areas. Nicotine (0.5 mg/kg s.c.) was found to increase firing rate and burst firing of dopaminergic neurons. In the presence of methyllycaconitine (MLA, 6.0 mg/kg i.p.) nicotine only increased firing rate. Moreover, in the presence of dihydro-beta-erythroidine (DH beta E, 1.0 mg/kg i.p.), an antagonist at non-alpha 7 nicotinic receptors, nicotine produced an increase in burst firing without increasing the firing rate. Nicotine also increased Fos-like immunoreactivity in dopamine target areas, an effect that was antagonized with MLA but not with DH beta E. Our data suggest that nicotine's augmenting effect on burst firing is, indeed, due to stimulation of alpha 7 nicotinic receptors whereas other nicotinic receptors seem to induce an increase in firing frequency.