The micro-computed tomographic images represent unusual root canal anatomy in a maxillary second molar with two palatal roots and two buccal roots in a 53-year-old female (Figure 1A–F). The patient had no history of systemic disease; the maxillary second molar was extracted because of periodontal disease. Scanning was performed with an X-ray micro-computed tomography (micro-CT) system (SMX-90; Shimadzu, Kyoto, Japan). The tooth was imaged to reconstruct its structure.

The common root anatomy of maxillary second molars has been described as three roots with three canals [1]. However, the number of root canals and roots among teeth can vary. The prevalence of maxillary second molars with two palatal roots was only 0.4% in a radiographical survey of 1,200 teeth [2]. Although the incidence of maxillary molars with four roots is extremely low, this possibility should be taken into consideration during treatment.

Radiographs are one of the most important tools for detecting anatomical variations in clinical dentistry [3] . However, radiographs produce only two-dimensional images of a three-dimensional object, resulting in superposition of structures. Radiographic interpretation was confusing in this case because of the overlap of the buccal and secondary palatal roots, indicated by a white arrow in (Figure 1D). Superposition of anatomical structures on X-ray images could result in failure to diagnose a distal palatal root canal, which, if left untreated, could result in failure of root canal treatment.

In recent years, significant noninvasive technological advances in dental imaging have been introduced, including digital radiography, densitometry, magnetic resonance imaging, ultrasound, and computed tomography [4]. In particular, micro-CT scan has been used to evaluate root canal anatomy because of its high resolution and non-destructive nature. The development of micro-CT scan is increasingly important in endodontic research because it offers a reproducible technique that can be applied quantitatively as well as qualitatively for the 3D assessment of the root canal system.

The existence of extra roots in maxillary molars has clinical implications in endodontic treatment [5]. Its posterior location and the radiographic superimposition of anatomic structures are two important reasons for failure to diagnose a second palatal root canal [6]. Endodontic treatment can fail because of the presence of microorganisms remaining after insufficient canal obturation or the presence of untreated canals [7]. The main goal of endodontic therapy is to obtain 3D obturation of the root canal system after a sequence of cleaning, shaping, and filling procedures [8].

A thorough knowledge of root and root canal morphology and accurate anticipation of a tooth’s possible morphological variations are essential for reducing endodontic failure caused by incomplete root canal preparation and obturation. Variations in the root and root canal morphology are a constant challenge for dentists. Dentists need to be familiar with the variations in root canal configurations for successful endodontic therapy. Micro-Computed tomography scan could be a useful tool for assessing root canal system anatomy in experimental endodontic studies.

Keywords: Micro-computed tomography, Molar, Root, Teeth

1. Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol. 1984 Nov;58(5):589–99.   [CrossRef]   [Pubmed]    
2. Libfeld H, Rotstein I. Incidence of four-rooted maxillary second molars: Literature review and radiographic survey of 1,200 teeth. J Endod. 1989 Mar;15(3):129–31.   [CrossRef]   [Pubmed]    
3. Slowey RR. Radiographic aids in the detection of extra root canals. Oral Surg Oral Med Oral Pathol. 1974 May;37(5):762–72.   [CrossRef]   [Pubmed]    
4. Blattner TC, George N, Lee CC, Kumar V, Yelton CD. Efficacy of cone-beam computed tomography as a modality to accurately identify the presence of second mesiobuccal canals in maxillary first and second molars: A pilot study. J Endod. 2010 May;36(5):867–70.   [CrossRef]   [Pubmed]    
5. Alenazy MS, Ahmad IA. Double palatal roots in maxillary second molars: A case report and literature review. Saudi Endod J 2015;5(1):56–60.    
6. Nabavizadeh M, Abbaszadegan A, Mirhadi H, Ghahramani Y. Root Canal Treatment of a Maxillary Second Molar with Two Palatal Canals: A Case Report. J Dent (Shiraz). 2015 Dec;16(4):371–3.   [CrossRef]   [Pubmed]    
7. Fakhari E, Shokraneh A. A maxillary second molar with two separate palatal roots: A case report. J Dent (Shiraz). 2013 Jun;14(2):87–9.   [Pubmed]    
8. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am. 1974 Apr;18(2):269–96.   [Pubmed]