Single root molars prevalence and its significance in human dental evolution

Title : Single root molars prevalence and its significance in human dental evolution

Abstract:

Background and Aim: Anatomic variation in root morphology of permanent molars that have been reported pertain to the presence of additional roots, canals or fused roots and C-shaped canals. The occurrence of a single root in molars (SRM) is rare. The aim of the study was to determine the prevalence of single root molar in a large sample of Israeli population and to correlate the crown size of SRM to dental evolution of HSS.

Methods: 2425 panoramic radiographs of modern healthy patients were examined on a light table and the prevalence of SRM was determined. The crown width (MD) of the mandibular second molars of normal two rooted molars, single root molars and homologue two-rooted molars were measured using a digital caliber on a light table. The results of the crown width were compared to anthropological populations (Early HSS and Neanderthals) and archeological population from excavations in Israel from 5000 BC to 13-19 century AC.

Results: The prevalence of single root molars (Figs 1,2) in the modern population was 6.13%. No significant differences were found between males and females. In the upper jaw single root molar was found in both first and second molars while in the lower jaw only second molars showed SRM. In both the Neanderthal and Early HSS groups 1 case with single root molars was found. No single root molars was found in the archeological groups from Israel excavations (5000 years BC till 19^th century AC).

The size of the crown was relatively stable  during evolution but during the modern period the MD size of the crown was significantly reduced. The crowns of the molars with single root showed significant reduction in comparison to two-rooted molars and the differences are significant statistically (P value<0.01). The homologue two-rooted second molars showed results between the normal population and single root molars. 

Discussion: This is the first analysis of the prevalence of single root molar in a large population of Israel. The results showed that the crown size is decreasing during the modern period and this reduction is increasing in single root molars, implicating that an on-going reduction in tooth size is happening, probably due to reduction of jaw size and the changes in food processing. More than that, single root molars is associated with higher percentages of impacted upper canines (9.9% VS 4% in the general population).

Biography:

Uri Zilberman received his DMD degree in 1983 from the Dental Faculty, Hebrew University, Jerusalem, and his PhD degree in 2000 on basic dental science, especially dental anthropology. Dr. Zilberman has a specialist degree in pediatric dentistry from 1990 and treated children and adolescents for the last 40 years. Prof. Zilberman is the head of the Pediatric Dental Unit at Barzilai Medical University Center, a unit recognized for specialization in pediatric dentistry since 2007. Associated Professor at the Faculty of Health Science, Ben-Gurion University of the Negev, Beer-Sheva, and teaches a course on Pathophysiology of the Oral Cavity for fourth year pharmacology students. Prof. Zilberman published more than 90 research papers and chapters in pediatric dentistry and dental anthropology. His main interests are new dental procedures and devices for pediatric dentistry, hereditary disorders and their effect on tooth development, and the use of biomimetic materials in pediatric dentistry, like Glass-Ionomers Cements. He developed new dental procedures and a patented new dental device for pediatric dentistry.