Successful endodontic treatment of teeth requires knowledge related to root canal morphology. Maxillary second molar is similar to maxillary first molar, which is smaller in all parameters. Maxillary second molar usually has three root canals of which two are on the buccal side and correspond with its roots, and palatinal canal which also corresponds with this root [1] .

Cases of maxillary second molar with two palatal roots [2] , four roots [3] , three bucal roots [4] and five roots [5] have been previously reported in literature. Variations have also been reported in the form of fewer or lesser number of canal [6] .

These roots have internal anatomic variations and might usually have a C-shaped canal configuration [7] .

Fava et al. [6] reported a single root and a single canal on the maxillary and mandible second molar. This feature is more often on lower mandible molars, but it can also appear on maxillary molars, other molars and premolars. Therefore, the majority of studies related to variations of maxillary molars are related to first molar since variations of maxillary second molar are rare.

There are various methods applied to describe complicated configuration of teeth root such as: longitudinal and transversal teeth projection, the system of root canal traces with resin and silicon, the technique of irrigation of canal by injecting hematociclyne and india ink color, in vivo and ex vivo research, radiographic assessment, application of electronic microscope, application of operative microscope and a loop, computer three-dimen- sional reconstruction and micro-computerized tomography [8] .

The aim of this clinical case presentation was to describe the unusual anatomic area of maxillary second molar.

A 25-year-old female patient visited the Department of Conservative Dentistry and Endodontic in University Dental Clinical Center of Prishtina, Kosovo. Clinical examination revealed occlusal composite restoration. Her primary complain, was spontaneous pain on the left maxillary second molar. The tooth was sensitive in vertical percussion, coldness and warmness. Pain appeared more frequently during the night lasting 2 to 3 hours with brief calming periods. The clinical examination was associated with radiographic (Sirona Siemens, Germany) and orthopamographic imaging (Owandy, France).

As mentioned, in the radiographic and orthopantomographic (OPG) image of both maxillary second molars was observed an unusual morphology. Both maxillary molars had only one root with a single apex and a single wide canal localized in the central part of the root, (anatomic classification according to Fan) [9] , compared to mandible second molars, which had a normal root and canal morphology (two roots, three canals) (Figure 1 and Figure 2).

After plexus anesthesia Articaine HCl. 4% with Epinephrine 1:100,000 Injection (Septocaine, Septodont, France), the cavity was opened. After removal of the restoration the trepanation was done. Working length was determined by Apex locator (Dentaport, Morita, Japan). Root canals were cleaned and shaped using K-Files (K-Reamers, Edenta le, Swiss) with conventional method. After each instrumentation the canal was irrigated with 2.5% NaOCl solution (Sodium Hypochlorite Solution, Sigma Aldrich-Germany). The inorganic component was removed with EDTA (Ethyilendiamine tetra acetic, acid disodium salt dehydrates, Czech Republic) solution with 17% concentration and final irrigation was done with a physiological solution NaCl 0.9% (B-Braun, Germany). After tooth canal instrumentation the root was dried with a sterile paper point. The gutta-percha (Dia Dent, Korea) was placed with a temporary filling to conduct a test image (Figure 3).

After the imaging the teeth root canal was obturated with cold lateral guttapercha with Canason (Vocco, Germany) and a lateral condensation of gutta-percha. To verify the filling, the patient’s tooth was imaged again (Figure 4).

The variation of maxillary second molar with single root and single canal is easily to detect in routine radiographs, as in this case. The use of multi angled diagnostic radiographs may be very useful on diagnosis of typical cases. However, care should be taken to assess the correct anatomy on the preoperative radiograph. In this way, we can reduce confusion with another anatomic variation of the same tooth where two roots are present (bucal and palatal), that could be superimposed on the diagnostic radiograph.

Conventional intraoral periapical radiographs are in important diagnostic tool in endodontics for assessing the root morphology and canal configuration. [10] Recently newer diagnostic methods such as computed tomography (CT) and spiral computed tomography (SCT) overcome the disadvantages of radiographs by producing a these dimensional image. These imaging techniques have emerged as powerful tools for evaluation of root canal tomography [11] .

During the discussion of this presentation, there are two important aspects to consider. Firstly, there is the presence of an unusual morphology in the maxillary second molar and secondly there is a morphological change in both maxillary sides. Our research partially corresponds with Fava et al., [6] since he has encountered four second molars of both upper and lower jaws with single root and single canal, compared to our study where this feature was found only on maxillary second molars.

In endodontic literature more is written about maxillary second molars with triple roots and triple canals compared to maxillary second molar that could have a single root and a single canal [12] [13] . Variations of the maxillary second molars are reported in numerous studies in vitro and in vivo.

Hartwell & Bellizi [14] concluded that the maxillary second molar with a single root and a single canal is present in 0.6% of cases. Peikoff et al. [15] in their retrospective study included 520 treated teeth in endodontic

way, primarily maxillary second molars. Based on their radiographic study they found that 3.1% of these teeth had a single root and a single canal. In their research Carlsen et al. [16] included 104 teeth with single root, primarily maxillary second molars. They did cut teeth in the cement-enamel junction, in the middle of the root and another cut in the apical part of tooth. Their study of teeth cut in the middle of the root concluded with 25.96% of cases of examined teeth had a single canal found on the central part of the root. Their study was conducted using stereo-microscope.

Libfeld and Rotstein [3] reported of the incidence of maxillary second molar with single root and single canal in their in vivo study. They assessed 200 radiographies of patients treated in an endodontic way and reported that this feature was evident in 0.5% of cases. Similar results were also found by Rwenyonyi et al. [17] but in fused roots of maxillary second molar. On the other hand, according to Hua XI et al. [18] the incidence of maxillary second molar with single root and single canal is very rare. YL Ng [19] and Alavi [2002] [20] failed to find a case in their 77 maxillary second molar with a presence of a single root and a single canal. These teeth variations can be easily detected via radiography. However, one should be careful of the superimposition of root and the image gained by radiography. If in daily practice an unusual anatomic image is found, it is preferred that the same image is done in the other side of the jaw. Also according to Fava and Dummer, when aiming to obtain additional information there should be conducted radiography of tooth in mesial-distal direction. From a clinical staind point when the initial radiograph shows the image of unusual anatomic it is recommended to take a radiograph of the contralateral tooth [21] . Yang et al. in their study reported that maxillary second molars had fused roots in 40.1% [22] . Fused roots or incompletely separated roots are common in the maxillary second molars amongst Chinese people, while C-shaped roots and root canals in maxillary molars are not frequently seen. In another study, in Chinese population the incidence of single root in the maxillary second molar has been found in 10% with CBCT [23] .

Kim et al. in Korean population, found that the incidence of fused roots was 0.73% in the first molars and 10.7% in second molars withy cone beam computed tomography [24] .

In endodontic practice variations of root and canals of molars in the same side of jaws can be found as well. Bernatti et al. [25] in their study included 97 teeth of maxilla and mandible. They studied the connection in counter-lateral pairs of unusual anatomic presence. They also described the presence of fused roots in maxillary second molar and mandible. Through radiography they found the presence of maxillary second molar with a single root and a single canal, and a similar feature in the other side of the jaw. They concluded that teeth of the same group, in both sides of the jaw, with the same patient, have a similar anatomic morphology which also found in our study.

Although the incidence of single root and single canal is not high. For this reason, it is important to take these variations into consideration during root canal treatment of maxillary molar in order to ensure success. On the other hand these teeth have good endodontic prognosis, because of wide and accessible canal.

Anatomic variations such as: fusion, germination or anomalies of tooth root can often be diagnosed by radiography. Therefore, the usage of various angulations during radiographic imaging assists us in revealing these un- usual cases in tooth root and canal. The use of CBCT provides new capabilities for assessment of the morphology and root anatomy of molar teeth. CBCT must be used in those cases where the conventional radiographic examination is not conclusive concerning the presence or absence of a supernumerary root. Even though the occurrence of maxillary second molar with a single root and a single canal is not high, diagnosing these unusual cases is of tremendous importance for successful endodontic treatment of these teeth.