JICDRO is a UGC approved journal (Journal no. 63927)

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Year : 2020  |  Volume : 12  |  Issue : 2  |  Page : 148-153

Three-Dimensional Analysis of the Nasopalatine Canal in Dentulous and Edentulous Maxilla – A Cone-Beam Computed Tomography Study

1 Department of Oral Medicine and Radiology, ITS Dental College and Hospital, Greater Noida, India
2 Department of Oral Medicine and Radiology, MGV's KBH Dental College and Hospital, Nashik, Maharashtra, India
3 Department of Oral and Maxillofacial Surgery, MGV's KBH Dental College and Hospital, Nashik, Maharashtra, India
4 Department of Oral Medicine and Radiology, S.G.T Dental College and Hospital, Gurgaon, India

Date of Submission16-Apr-2020
Date of Decision25-Jun-2020
Date of Acceptance10-Jul-2020
Date of Web Publication14-Dec-2020

Correspondence Address:
Dr. Gayatri Mehrotra
240 Nehru Nagar, Agra - 282 002, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jicdro.jicdro_18_20

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Introduction: Dental esthetics has become an important concern today, and the patients consider the esthetic outcome to be an important factor in the anterior maxilla. Nasopalatine canal (NPC) plays an important role in making decisions regarding implant placement in the anterior maxilla. The aims of the present study were to analyze and compare the length and diameter of NPC and bone dimensions anterior to the canal in dentulous and edentulous maxilla for dental implant consideration using cone-beam computed tomography (CBCT). Materials and Methods: Sixty CBCT scans were collected retrospectively for the examination of NPC of individuals who had undergone CBCT scans for dental treatment purposes. The length of the canal and bone dimensions anterior to the canal were measured in multiplanar reformation. Results: The mean canal length was less in edentulous than dentulous patients. Moreover, the bone width anterior to the canal and bone height were also more in dentulous patients, with mean bone width being 8.518 ± 1.9 mm and bone height 7.993 ± 1.4 mm. The bone width and bone height in edentulous cases were 6.910 ± 1.44 mm and 5.183 ± 1.1 mm, respectively. Conclusion: Although there are variations in each patient, thorough knowledge of NPC and bone dimension is essential for implant placement to avoid any complication.

Keywords: Cone-beam computed tomography, dental implant, dentulous, edentulous, maxilla, nasopalatine canal

How to cite this article:
Mehrotra G, Bhoosreddy A, Bhoosreddy S, Bhadage C, Sharma K, Shah K. Three-Dimensional Analysis of the Nasopalatine Canal in Dentulous and Edentulous Maxilla – A Cone-Beam Computed Tomography Study. J Int Clin Dent Res Organ 2020;12:148-53

How to cite this URL:
Mehrotra G, Bhoosreddy A, Bhoosreddy S, Bhadage C, Sharma K, Shah K. Three-Dimensional Analysis of the Nasopalatine Canal in Dentulous and Edentulous Maxilla – A Cone-Beam Computed Tomography Study. J Int Clin Dent Res Organ [serial online] 2020 [cited 2021 Jun 19];12:148-53. Available from: https://www.jicdro.org/text.asp?2020/12/2/148/303398

   Introduction Top

Today, with the rapid emergence of the need of dental implants in the field of dentistry, the importance of three-dimensional (3D) imaging is ever increasing and this is mainly because of a drastic increase in accidents leading to tooth loss which are taking place nowadays.[1],[2],[3] There has been a paradigm shift from 2D to 3D. Over the past years in India, dental esthetics has become an important concern in dentistry. Moreover, the patients consider esthetic outcomes to be an important aspect, particularly in the maxillary anterior region.[4]

Anatomy and position of the nasopalatine canal (NPC) [Figure 1] is essential for implant placement in the maxillary anterior region not only in terms of success but also from an esthetic point of view.[5],[6],[7],[8],[9],[10],[11] Moreover, NPC has a tendency to increase in size with aging and also following tooth extraction.[12] Stenson was the first to give a description of NPC in 1683.[13]
Figure 1: cross-sectional view of CBCT showing heart-shaped nasopalatine canal

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NPC, also known as the incisive canal, is located in the midline of the palate, behind maxillary central incisors. It connects the roof of the oral cavity to the floor of the nasal cavity. The incisive canal has two openings – superior opening known as nasopalatine foramen and inferior opening known as the incisive foramen.[14] Incisive foramen which is a funnel-shaped opening of the canal in the midline of the anterior palate is located beneath incisive papillae and marks the exit of the nasopalatine nerve. The canal ends in the nasal cavity and terminates with two openings on either side of the nasal septum known as Stenson’s foramina.[15] Nasopalatine nerve along with terminal branch of nasopalatine artery transmits through the canal whereby nasopalatine nerve supplies a lower third of the nasal septum. It is connected to the greater palatine nerve and also supplies the anterior portion of the hard palate.[16]

The NPC shows a great deal of variability with regard to its dimension as well as morphological appearance. It’s important to analyze a precise 3D anatomic description of NPC to enable safe and accurate planning and placement of dental implants. The morphological appearance includes the shape, curvature, angulation, and dimension of the canal. NPCs have been classified into four categories according to shape on sagittal sections: cylindrical, funnel, spindle, or hourglass. Based on the curvature, four types of NPCs have been noted: vertical, vertical curved, slanted, and slanted curved. The mean angulation of NPC has been considered to be 63°.[17] The directional course of NPC and the nasopalatine angle must be assessed for the placement and angulation of future dental implants in this area. However, to the best of our knowledge, there is no scientific evidence to correlate the tridimensional NPC shape.[18]

Bone density seems to strongly influence implant stability and long-term success, as demonstrated by the higher implant survival rates in the mandible compared to the maxilla, especially the posterior maxilla. Clinicians generally consider that the basic cause of the difference in the survival rates between the maxilla and mandible is bone quality. The bone around the implant has better quantity and quality in the mandible than the maxilla, thus showing a high success rate.[19]

Insertion of an implant in the incisive canal may lead to contact of implant with neural tissue leading to sensory alteration and may even cause nonossteointegration.[20],[21] In some cases, nasopalatine duct cyst formation has also been reported in relation to dental implant placement.[22] In addition, an enlarged canal complicates osteotomy during implant surgery.

To prevent all the above complications, the morphology of NPC needs to be properly evaluated before implant placement. The presence and absence of maxillary teeth also affect the bone because a high resorption rate occurs post-extraction. Thus, there is a need to evaluate the dentulous and edentulous cases. Therefore, the aim of the present study was to analyze and compare the length and diameter of NPC and bone dimensions in dentulous and edentulous maxilla for dental implant consideration.

   Materials and Methods Top

A total of 60 CBCT scans were collected retrospectively for evaluation of the morphology of NPC individuals who reported to the Department of Oral Medicine and Radiology at MGV’s K.B.H Dental College and hospital, Nashik, for their CBCT scans for dental treatment purposes. Of 60 scans, 30 were dentulous scans (Group A) and 30 were edentulous scans (Group B). The age of subjects was in the range between 18 and 80 years.

Exclusion criteria – patients with any nasopalatine pathology and low-quality imaging scans were excluded from the study.

Machine specifications used are as follows:

  • Model designation – Orthophos XG 3D
  • Nominal voltage – 200 V − 240 V
  • Focal spot size – 0.1 mm3
  • Kv – 85kV
  • mA – 5 mA/7 mA
  • Field of view – 8 cm × 8 cm

The following parameters were evaluated and measurements were done in the multiplanar reformation view in the sagittal section.

  1. Length of the canal
  2. Bone width anterior to the canal (at two levels)
  3. Bone height anterior to the canal.

The length of the canal was measured as the distance from the nasal opening (nasal floor) up to the oral opening (oral floor) [Figure 2]. The bone width anterior to the canal was measured at two levels. First, at the level of nasal spine because the implants are not placed above the level of the nasal spine and second at the level of opening of the canal because at this level, the dentist needs to be more careful so that they do not perforate the NPC [Figure 3]. Height of the bone was measured anterior to the canal from bone adjacent to the opening of canal up to the most inferior portion of the bone [Figure 4]. All the three parameters were evaluated both for dentulous and edentulous cases. The data were entered into Microsoft excel and analyzed statistically in SPSS software (chicago). Mean ± standard deviation were calculated. Student unpaired t-test was done to compare the data between dentulous and edentulous patients.
Figure 2: sagittal view in MPR showing length of NPC measured from roof of the oral cavity to the floor of the nasal cavity (red line)

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Figure 3: sagittal view in MPR showing bone width at 2 levels-yellow line indicating bone width at the level of nasal spine and red line indicating bone width at the opening of the canal

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Figure 4: sagittal view in MPR showing height of bone (red line) from alveolar crest upto canal opening

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Ethical Clearance

Ethical approval for this study was provided by the Institutes (MGV’s K. B. H Dental College and Hospital, Nasik) Ethical Committee on 2 March 2018.

   Results Top

The study evaluated 60 CBCT scans and divided them into two groups. Group A had 30 dentulous and Group B had 30 edentulous cases. The mean canal length came out to be 10.38 ± 2.1 mm in Group A and 8.126 ± 1.32 mm in Group B. The bone width at the level of the nasal spine (at crestal level) was 11.016 ± 2.2 in Group A and 9.725 ± 1.8 in Group B. The bone width at the opening of the canal (at apical level) was 6.021 ± 1.6 in Group A and 4.096 ± 1.08 in Group B. The height of the bone anterior to the canal was 7.993 ± 1.4 mm in Group A and 5.183 ± 1.1 mm in Group B. The mean value for both the groups is shown in [Table 1]. The length of the canal was less in the edentulous maxilla compared to the dentulous maxilla, and this difference was statistically significant (P < 0.0001). Bone dimensions also differed in both the groups. Bone width as well as bone height anterior to the canal was higher in dentate patients, and the difference was statistically significant [Figure 5],[Figure 6],[Figure 7].
Figure 5: graphical presentation showing comparison of length of the canal between Groups A and B

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Figure 6: graphical presentation showing comparison of mean bone width between Groups A and B

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Figure 7: graphical presentation showing comparison of bone height anterior to the canal between Groups A and B

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Table 1: Length of canal, Bone width and Bone Height (Mean ± SD) in both groups

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   Discussion Top

Implant planning in maxillary anterior is a major issue nowadays. Following the tooth extraction, bone resorption takes place which is an unavoidable event leading to changes in morphological features of the jaw bone.[23],[24],[25],[26] Moreover, maxilla has a thinner cortical plate in comparison to the mandible. Thus, implants in the maxilla have a low survival rate with a risk of poor prognosis, making it necessary to find a suitable site for implant placement.[27]

Due to the close anatomical relationship between NPC and root of maxillary central incisors, implants need to be placed in this region with great caution. A careful radiological analysis is thus required at the time of implant planning. In the present study, the length of NPC in dentulous and edentulous patients was recorded as 10.38 ± 2.1 mm and 8.126 ± 1.32 mm, respectively. The result co-related with the study conducted by Tözüm et al.[28] where the length of NPC was more in dentulous (11.07 ± 2.7 mm) compared to edentulous patients (10.16 ± 2.48 mm). Moreover, Liang et al.[29] and Mraiwa et al.[30] found a mean length of 9.9 ± 2.6 and 8.1 ± 3.4 mm, respectively. In a study conducted by Song et al.,[14] the mean length of 11.5 was calculated which was quite similar to the results of other studies. Soumya et al.[31] conducted a study whereby they found mean canal length to be 18.63 ± 2.35 mm, which is longer compared to other studies conducted till date. These variations can be attributed to the anatomical variation found in different populations.

Although a number of augmentation techniques can be performed to modify the bone thickness and height, the bone dimensions anterior to the canal are an important parameter which needs to be considered during implant placement. In the present study, bone height anterior to the canal was 7.993 ± 1.4 mm in dentulous and 5.183 ± 1.1 mm in edentulous patients. However, Tözüm et al.[28] found mean length anterior to the canal to be 19.17 ± 1.3 mm, where minimum bone length recorded was 8 mm. However, the bone length was found to be more in dentulous than in edentulous patients which was the same as found in the present study. Mardinger et al.[12] found that the bone length was 17.22 mm in Class A ridge (ridge with full dentition in premaxilla area) which decreased to 9.57 mm in Class E ridge (severely resorbed ridge), that is nearly 44.4% of the buccal bone length was lost.

The bone width was recorder at two levels, first at the level of the nasal spine which was 11.016 ± 2.2 mm in dentulous and 9.725 ± 1.8 mm in edentulous. Similarly, at the level of opening of the canal also, the bone width was more in dentulous than in edentulous patients which was 6.021 ± 1.6 mm and 4.096 ± 1.08 mm, respectively. Hence, the mean bone width was 8.518 ± 1.9 mm in dentulous and 6.910 ± 1.44 mm in edentulous patients. Tözüm et al.[28] found that the mean bone thickness anterior to the canal was 7.38 ± 1.42 mm in dentulous and 6.43 ± 1.49 in edentulous patients. Bone width anterior to the canal was 6.32 ± 1.43 mm in the study conducted by Soumya et al.[31]

The mean width for a standard diameter implant ranges from 2.8 to 11.8 mm. Mardinger et al.[12] found that the bone anterior to the canal lost 60% of its mean width. Bone width decreased from 6.4 mm in Class A ridge to 2.6 mm in Class E ridge with P < 0.01. Thus, they showed that there was a decrease in length as well as the width of the buccal plate with age. Tözüm et al.[28] also stated that canal length, bone length, and bone width anterior to the canal were greater in dentulous patients which was the same as found in our present study. Since maxillary anterior bone resorption occurs with age and following postextraction, there is a reduction in the canal length. Other studies also found the same result.[32],[33] In one of the study,[34] it was found that implants in NPC can also be considered as one of the treatment options for rehabilitation of severely atrophied maxilla. In this case, NPC was used as an anatomic buttress for the purpose of implant placement.

The strength of the present study is that it gives a detailed view about the implant planning in the anterior maxillary region in 3D radiograph in all three sections which is more appropriate than a 2D radiograph. Very few studies have been conducted till date in the Indian population taking both dentulous and edentulous cases into consideration. Moreover, the radiation exposure is also less in CBCT as compared to conventional computed tomography. The limitation of the study is that the sample size was small. Thus, a study with a larger sample size should be carried out. However, while considering the scope of the present study, we can say that a thorough knowledge of anatomic structures of NPC and its variation is essential to reduce the chances of complications in implant dentistry.

   Conclusion Top

Implant rehabilitation of an edentulous anterior maxilla is one of the most complex restorative challenges due to a number of factors affecting the esthetic and functional aspects of the prosthesis. Implant planning is a challenging task in edentulous cases because of the less bone available. Although variation exists, dental status is an essential factor affecting NPC and bone available anterior to the canal. Thus, for successful implant stability and to avoid postoperative complications, it is of utmost importance that implants are placed at a safe distance from the anatomical landmarks.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]

  [Table 1]


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