This study aimed to identify structural and functional craniofacial characteristics that correlate with high incidence of probable sleep bruxism in children. From March 2018 to March 2019, a cross-sectional clinical study was performed with ninety-six healthy children ages 6-12 years who presented for routine dental examination at the UCLA pediatric dental clinic. Variables of interest included: (1) assessment of probable bruxism based on parental awareness on the frequency of tooth grinding during sleep and clinical signs of bruxism based on tooth wear; (2) parental reports of mouth breathing while awake and asleep, snoring during sleep, difficulty breathing and/or gasping for air during sleep; (3) parental reports of psychosocial distress; (4) assessment of tonsil hypertrophy, tongue mobility, and nasal obstruction. The conclusion was that probable sleep bruxism was found to be significantly associated with impaired nasal breathing, habitual mouth breathing, restricted tongue mobility, and/or tonsillar hypertrophy. Restricted tongue mobility was found to be an independent risk factor for bruxism among individuals with normal nasal breathing. The study further shows that tonsillar hypertrophy, restricted tongue mobility, and nasal obstruction may have a synergistic association on the presentation of probable sleep bruxism.