Congenitally missing second permanent molars in non‑syndromic patients (Review)

Abstract

Hypodontia (tooth agenesis) is regarded as the most common congenital dental anomaly. The present review discusses the epidemiological characteristics of congenitally missing second permanent molars (CMSPMs) within a systematic review of the literature. The review was based on Pubmed library associated with the search of various scientific databases or academic resources, improved by hand search of reference lists. The terms 'hypodontia' or 'anodontia' in combination with 'prevalence' or 'epidemiology' were searched in the data sources for studies published between January 2001 and December 2020. Abstracts of non-English papers were also analyzed. The inclusion criteria were as follows: i) Study provided precise data about CMSPMs, even if no second permanent molar was reportedly missing; ii) the number of CMSPMs distributed by jaw was provided and iii) studies on subjects >3 years were used. The exclusion criteria were as follows: i) Studies on patients with history of trauma of the maxilla or the mandible, any type of syndrome affecting bone metabolism, metabolic disorders, previous extraction or tooth loss due to dental caries, cleft lip and palate; ii) studies performed on cohorts of patients with hypodontia and iii) studies reporting data including third molars, except for those that presented sufficient data to perform correct calculations. A total of 79 studies were selected, accumulating a population of 281,968 people, with an average sample size of 3,524.60±11,255.25. The prevalence of CMSPMs (IpHSPM) was 2.79±3.16% among all missing teeth (1.03±1.59% for upper CMSPMs and 1.76±2.32% for lower CMSPMs; P= 0.011). There were no significant differences (P= 0.250) in IpHSPM between men (1.59±1.52%) and women (2.13±1.67%). However, significant differences were recorded between continents. Furthermore, lower CMSPMs were found more frequently in orthodontic samples (P=0.033). The prevalence of CMSPMs is low compared with the overall prevalence of CM teeth. Despite the rarity of these anomalies, early detection is important to enable practitioners to plan and start treatment at the best time for optimal results.

Congenital Bilateral Missing of Permanent Mandibular Second Molars in a 10-Year-Old Child: A Case Report

“…The prevalence and type of hypodontia in different countries have been the topic of many previous investigations [ 5 ]. The reported prevalence of hypodontia ranges from 2.9% to 7.8% [ 5 , 6 ].…”

“…The prevalence and type of hypodontia in different countries have been the topic of many previous investigations [ 5 ]. The reported prevalence of hypodontia ranges from 2.9% to 7.8% [ 5 , 6 ]. Higher prevalence rates ranging from 19% to 36% have also been reported in some communities with diverse racial patterns and also in different geographical locations [ 5 ].…”

“…The reported prevalence of hypodontia ranges from 2.9% to 7.8% [ 5 , 6 ]. Higher prevalence rates ranging from 19% to 36% have also been reported in some communities with diverse racial patterns and also in different geographical locations [ 5 ].…”

“…Hypodontia most commonly involves the mandibular premolars, maxillary lateral incisors, and maxillary second premolars [ 5 ]. However, missing of permanent second molars is a rare occurrence with a very low prevalence rate [ 5 ].…”

“…Hypodontia most commonly involves the mandibular premolars, maxillary lateral incisors, and maxillary second premolars [ 5 ]. However, missing of permanent second molars is a rare occurrence with a very low prevalence rate [ 5 ]. To the best of the authors’ knowledge, only two studies have reported hypodontia of permanent second molars in orthodontic patients in Iran [ 7 , 8 ].…”