Mineralization of bones and teeth is tightly regulated by levels of extracellular inorganic phosphate (P) and pyrophosphate (PP). Three regulators that control pericellular concentrations of P and PP include tissue-nonspecific alkaline phosphatase (TNAP), progressive ankylosis protein (ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Inactivation of these factors results in mineralization disorders affecting teeth and their supporting structures. This study for the first time analyzed the effect of decreased PP on dental development in individuals with generalized arterial calcification of infancy (GACI) due to loss-of-function mutations in the ENPP1 gene. Four of the 5 subjects reported a history of infraocclusion, overretained primary teeth, ankylosis, and/or slow orthodontic tooth movement, suggesting altered mineral metabolism contributing to disrupted tooth movement and exfoliation. All subjects had radiographic evidence of unusually protruding cervical root morphology in primary and/or secondary dentitions. High-resolution micro-computed tomography (micro-CT) analyses of extracted primary teeth from 3 GACI subjects revealed 4-fold increased cervical cementum thickness ( P = 0.00007) and a 23% increase in cementum density ( P = 0.009) compared to age-matched healthy control teeth. There were no differences in enamel and dentin densities between GACI and control teeth. Histology revealed dramatically expanded cervical cementum in GACI teeth, including cementocyte-like cells and unusual patterns of cementum resorption and repair. Micro-CT analysis of Enpp1 mutant mouse molars revealed 4-fold increased acellular cementum thickness ( P = 0.002) and 5-fold increased cementum volume ( P = 0.002), with no changes in enamel or dentin. Immunohistochemistry identified elevated ENPP1 expression in cementoblasts of human and mouse control teeth. Collectively, these findings reveal a novel dental phenotype in GACI and identify ENPP1 genetic mutations associated with hypercementosis. The sensitivity of cementum to reduced PP levels in both human and mouse teeth establishes this as a well-conserved and fundamental biological process directing cementogenesis across species (ClinicalTrials.gov NCT00369421).

The critical incident technique (CIT) is a well-established qualitative research tool used in many areas of the health sciences, including nursing, medicine, and dentistry, and their respective education systems. It is a flexible set of principles that can be modified and adapted to meet the specific situation at hand. By gathering factual reports made by observers, researchers can build a picture of the situation under study. The CIT maximizes the positive and minimizes the negative attributes of anecdotes, effectively turning anecdotes into data. In this, the first of two companion articles, the origins and current state of the CIT and its potential applications in dentistry and dental education are described.

Congenital heart disease (CHD) is one of the most common developmental anomalies. Children with CHD are at increased risk of developing oral disease, and are at increased risk from the systemic effects of oral disease. Recent changes in guidelines related to prophylaxis against infective endocarditis have highlighted the importance of establishing and maintaining oral health for this group of patients. The management of children with CHD can be complex and, unfortunately, many of these children do not receive the care they require. The challenges that these children pose are discussed, and suggestions are made for the appropriate management of these patients and the key role that all those working in primary dental care have to play.