Diversity of clinical, radiographic and genealogical findings in 41 families with amelogenesis imperfecta

Abstract Amelogenesis imperfecta (AI) is a group of enamel development disorders that alter the structure and chemical composition of the tissue. There is great variability in the clinical presentation; according to Witkop, AI can be categorized into 14 subtypes, which makes its diagnosis extremely complex. Objective: This study aimed to describe and determine the frequency of clinical and radiographic features and inheritance patterns found in 41 Chilean families diagnosed with diverse types of AI. Material and Methods: We analyzed the clinical records, photographs, pedigrees and radiographs of 121 individuals recruited between 2003 and 2016. All of the information was included in a database that was analyzed using the application Stata 14. Results: The 72 affected individuals had average age of 16 years, and no sex association with the presence of AI was found. The most frequent clinical subtypes were as follows: 43% hypomature, 25% hypoplastic, 21% hypomature/hypoplastic, 7% hypocalcified and 4% hypocalcified/hypoplastic. The number of severely affected teeth was 22, which occurred in the patients with hypocalcified and hypocalcified/hypoplasic AI who presented the highest number of damaged teeth. Caries and periodontal disease were found in 47 and 32% of the patients, respectively. Malocclusions were observed in 43% of the individuals with AI, with open bite being the most frequent. Radiographically, the thickness of the enamel decreased in 51% of the patients, and 80% showed decreased radiopacity of the enamel compared to that of dentin. Autosomal dominant inheritance pattern was found in 37% of the families with hypoplastic AI, and autosomal recessive pattern was present in 56% of the other clinical subtypes, but more frequently in those affected with hypomature and hypocalcified AI. Conclusion: Of the five clinical subtypes, autosomal recessive hypomature, autosomal dominant hypoplastic and autosomal recessive hypomature/hypoplastic AI were the most prevalent subtypes in this group.摘要 牙釉质发育不全（Amelogenesis Imperfecta, AI）是一类可改变牙釉质结构与化学成分的牙釉质发育异常性疾病，临床表现存在高度异质性。根据Witkop的分类标准，AI可分为14种亚型，这使得其诊断难度极大。 目的：本研究旨在描述并明确41个确诊为不同类型AI的智利家庭中，临床与影像学特征及遗传模式的发生频率。 材料与方法：本研究分析了2003年至2016年间招募的121名受试者的临床病历、照片、家系图及影像学资料，所有信息均录入数据库，采用Stata 14软件进行数据分析。 结果：72名受累患者的平均年龄为16岁，未发现AI发病与性别存在关联。最常见的临床亚型依次为：低成熟型（hypomature）43%、发育不良型（hypoplastic）25%、低成熟/发育不良混合型（hypomature/hypoplastic）21%、低钙化型（hypocalcified）7%，以及低钙化/发育不良混合型（hypocalcified/hypoplastic）4%。共出现22颗严重受累的牙齿，均见于低钙化型及低钙化/发育不良型AI患者，该类患者的受损牙齿数量最多。47%的患者合并龋病，32%的患者合并牙周疾病。43%的AI患者存在错𬌗畸形，其中以开𬌗最为常见。影像学检查显示，51%的患者牙釉质厚度降低，80%的患者牙釉质相较于牙本质的X线阻射率降低。常染色体显性遗传模式见于37%的发育不良型AI家庭，常染色体隐性遗传模式见于56%的其余临床亚型患者，其中低成熟型及低钙化型患者的隐性遗传占比更高。 结论：在五种临床亚型中，常染色体隐性低成熟型、常染色体显性发育不良型及常染色体隐性低成熟/发育不良混合型AI为本研究队列中最常见的亚型。