Journal of Dental Implant Research 2024; 43(2): 19-25  https://doi.org/10.54527/jdir.2024.43.2.19
Obliteration and grafting of the nasopalatine canal for implant placement
Dexter Barber1 , Douglas Beals1 , John Francis1 , Trever Siu1 , Tyler Francis2
1College of Dental Medicine-Arizona, Midwestern University, Glendale, 2Francis Dental, Goodyear, Arizona, United States
Correspondence to: John Francis, https://orcid.org/0009-0002-1354-3517
College of Dental Medicine-Arizona, Midwestern University, Glendale, Arizona 85308, USA. Tel: +01-6238067074, E-mail: jfranc@midwestern.edu
Received: April 5, 2024; Revised: May 8, 2024; Accepted: May 8, 2024; Published online: June 30, 2024.
© The Korean Academy of Implant Dentistry. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
This case report presents the use of cone beam computed tomography for treatment planning of a nasopalatine defect requiring enucleation and bone grafting to replace the left maxillary central incisor with an implant. This procedure enables the implant to be placed in a position appropriate for successful osseointegration and produces outcomes that meet the esthetic and functional requirements of the anterior maxilla.
Keywords: Bone grafting, Dental implant, Image guided surgery
INTRODUCTION

Dental implant placement in the anterior maxilla requires proper planning to ensure that the implant is placed in the correct position esthetically and func-tionally.1-7) The anatomy in the anterior maxilla, and more specifically, the central incisor region, can present obstacles and limitations in the placement of implants in this location.2,3,6-12) These obstacles include a decrease in the quantity of alveolar bone, secondary to maxillary bone resorption, in both width and height.1,4) The anterior maxilla, may have other anatomical limiting factors, such as, an enlarged nasopalatine canal (NPC).1,4-9) Such anatomical limitations were noted early by Branemark, and more recently, Bahshi and others have reported on the numerous anatomic variations of the NPC that must be considered when performing implant surgery in this region of the maxilla.2,4-7) The three dimensional image acquired through cone beam computed tomography (CBCT) is imperative when implant planning in this region. Through the use of the three-dimensional imaging and planning software, the need for lateralization, obliteration and grafting at NPC sites can be determined.5-7,9-12) The associated nasopalatine artery and nerve also provide neurological and vascular limitations and obstacles, as well as potential risks and possible complications to routine implant surgery.10-12)

Ultimately, the surgeon must utilize three-dimensional cone-beam computed tomography (CBCT) planning for localizing the appropriate implant position for maxillary central incisor implants.4,7) The NPC should be assessed at this time to determine if obliteration or enucleation, followed by bone augmentation is recommended.2,4,7) The long term success of the implant is dependent upon implant placement in the correct position.1-4,7)

This case report describes the surgical technique of site development at the missing tooth area of the left maxillary central incisor, which includes obliterating the enlarged nasopalatine canal and bone grafting the canal to provide the appropriate bone width on the palatal side, for an implant in the proper planned restoratively-driven location. This case report will also feature the use of guided implant surgery, ISQ radiofrequency technology for measuring implant stability, and immediate provisional restoration.

CASE PRESENTATION

A 62-year-old male presented to the dental clinic of the College of Dental Medicine, Midwestern University Arizona, due to a suspected vertical root fracture and infection of the left maxillary central incisor. The tooth had been successfully treated endodontically 34 years earlier, but then complications arose, and the tooth required evaluation and treatment. A CBCT demonstrated a fenestrated defect of the buccal plate and insufficient bone volume from a thin, deficient maxillary ridge (Fig. 1). In addition, the planned implant site involved the enlarged nasopalatine (NP) canal. The presence of an NP cyst was considered but ruled out based on the lack of usual symptoms such as teeth displacement, palatal swelling, pain, or discharge.9) For proper implant placement at the proposed site, canal space would need to be utilized (Fig. 2). Nasopalatine canal enucleation and bone grafting, additional grafting of the residual socket and missing buccal plate, along with the associated risks and complications were discussed with the patient.

Figure 1. Pre-extraction CBCT demonstrates fenestrated defect of the buccal plate and a thin maxillary ridge.

Figure 2. Axial CBCT view showing that canal space would need to be used in order to place the #9 implant in the proper position.

In preparation for the surgery, the patient began taking a methyl prednisolone dose Pak (Pfizer Inc, New York, NY, USA), 2 mg tablets, dosed per manufacture instructions, one day prior, and was prescribed an amoxicillin regimen to take 1 gram 1 hour before the procedure and then 500 mg every 8 hours for one week after the surgery. Following local anesthesia, full-thickness flaps were elevated both facial and palatal from teeth #6-11 with facial vertical releasing incisions bilaterally. The tooth was extracted atraumatically without complications. Two bony defects, one at the apex and one mid- root were noted due to chronic inflammation, but no current infection was present. The area was debrided of all soft tissue with rotary and hand instrumentation and the contents of the NP canal extirpated. A #8 round bur was used to decorticate the area. Buccal flap periosteum was released to allow for flap advancement and a relaxed closure. Jason membranes, (Straumann USA, LLC) native collagen membranes derived from porcine pericardium, were sized, and trimmed to cover the graft area buccally and pallatally. Mineralized/demineralized AlloOss allograft (Ace Surgical Supply Inc., Brockton, MA, USA) was hydrated with GEM 21, (Geistlich Pharma North America, Princeton, NJ, USA) a growth-factor enhanced matrix containing purified rhPDGF-BB and beta Tricalcium Phosphate, along with autogenous bone harvested with a bone scraper. Mineralized cortical bone (Ace Surgical Supply Inc, Brockton, MA, USA) was hydrated also with GEM 21 and overlaid the graft site on both the buccal and palatal with a small amount of NuoOss, (Ace Surgical Supply Inc, Brockton, MA, USA) a natural xenograph material produced by the removal of all organic material from bovine bone. The prepared Jason membranes were stretched over the graft material and secured with fixation screws and the surgical site was closed with 4-0 and 3-0 Cytoplast (Osteogenics, Lubbock, TX, USA) suture.

A flattened resorbable collagen plug (Ace Surgical Supply Inc, Brockton, MA, USA) was placed over the top of the socket area since primary closure was not possible at the socket with a resultant 1∼2 mm gap.

The crown of the extracted tooth was sectioned off and the exposed canal retro-filled with composite. At a subsequent visit, that crown was then splinted onto the adjacent dentition spanning across the edentulous site utilizing ribbond and flowable composite (Fig. 3). The pontic was placed slightly into the gingival tissue to encourage the development of an optimal soft-tissue emergence profile.

Figure 3. Crown of extracted tooth #9 splinted to adjacent teeth to function as a temporary restoration.

The patient returned seven months later for a new CBCT evaluation of the grafted site and preliminary implant planning. Cross-sectional and axial imaging showed favorable thickness of the implant site with an adequate volume of regenerated bone (Fig. 46).

Figure 4. CBCT 7-months post-graft, cross-sectional view #9 site.

Figure 5. CBCT 7-months post-graft, cross-sectional view #9 site, before and after graft.

Figure 6. CBCT 7-months post-graft, axial view #9 site.

The patient presented to his restorative dentist for clinical consultation and guided surgical implant planning. An intraoral digital scan was taken of the patients full upper and lower arch using the ITERO Element Plus Series (Align Technologies, San Jose, CA, USA). STL files of the arches and the CBCT were sent to DIO Implant, Whitecap Dental Laboratory (Heber City, Utah, USA). A digital 3-D planned surgery plan was then created (Fig. 7, 8).

Figure 7. DIO implant planning image.

Figure 8. Image of implant surgical proposal.

The surgical plan was sent back from the laboratory for approval of the planned implant placement.

Upon approval of the surgical plan, an appropriately sized implant was selected for the site. A customized anatomic healing abutment was also selected, along with a provisionally cemented temporary, to be designed by the same Whitecap Dental Lab.

On the day of surgery, premedication of 2,000 mg of Amoxicillin was taken by the patient an hour before the appt. Upon arrival, the patient was instructed to rinse with 0.12% Chlorhexidine Gluconate. Removal of the fixed temporary crown was done by using high-speed handpiece to remove the composite securing the temporary crown, and then the crown was removed.

After local anesthetization, the digitally created surgical guide (Dionavi, Pusan, Korea) was verified on the patients' dentition, a flapless exposure drilling protocol followed, and a 4.0×11.5 Dio fixture was placed, fully guided thru the surgical guide, with an insertion torque of 35 N-cm (Fig. 9). Implant Stability Quotient (ISQ) readings were obtained with an Osstell unit (Gothenburg, Sweden) which measured: B=90, P=87, M=87, D=87. The custom anatomic healing abutment was then delivered (Fig. 10).

Figure 9. Implant placed with flapless exposure.

Figure 10. Anatomic abutment placed at the time of implant placement.

The previously fabricated temporary crown was cemented using temporary cement and was taken out of occlusion in all movements (Fig. 11).

Figure 11. Anatomic abutment and temporary crown placed at the time of implant placement (out of occlusion).
DISCUSSION

The nasopalatine canal is in the middle aspect of the maxillary bone, posterior to the central incisors. It extends from the nasal cavity to the oral cavity and its main contents include the nasopalatine nerve and the nasopalatine artery.7) The nasopalatine nerve and artery supply sensory and vascular support to the anterior part of the hard palate, nasal septum, and the palatal gingiva.

The purpose of the nasopalatine canal is to transmit vascular and sensory information such as pain and temperature from the anterior palate to the brain.1) With many anatomical variations of the canal and its contents being reported in the literature,4) it is imperative that the implant surgeon is familiar with the morphology of the nasopalatine canal, through a three-dimensional imaging CBCT analysis, during the planning of the implant case. It should be noted that as the patient ages, the NPC increases in size, and the surgeon should anticipate a larger enucleation and bone defect to repair.6,13)

The enucleation of the NPC is a procedure that has surgical risks which include injury and/or damage of the neurosensory and vascular supply.10-12,14,15) Singhal and others have reported that some form of anterior palatal tissue numbness will occur with enlarged incisive canal and nasopalatine canal regions.1) It is the authors’ observation that the majority of our patients that undergo enucleation of the nasopalatine canal have some form of lingering palatal soft tissue numbness. The vascular and neurological supply from the greater palatine nerve and artery to this region of the anterior maxilla can help to reinnervate and revascularize this area, minimizing potential complications, such as paresthesia.10-12,14,15)

Misch describes the clinical significance of the nasopalatine canal when treating the pre-maxillary area, and states that caution should be taken when working in that area, but the presence of the canal or even the slight encroachment of the canal in the implant process is not a contraindication to implant placement.16) Also, within reason, and without the presence of cystic tissue, all sizes and shapes of the nasopalatine canal can be used as potential implant space. If the implant invades the canal space, removal of the canal tissues and grafting, or continuing with the implant placement with slight encroachment into the canal, are both viable options.16)

However, if soft tissue is the predominant tissue around the implant, failure of osseointegration may occur, as well as neurosensory changes and/or bleeding complications during the surgery.

When it comes to utilizing the space occupied by the incisive canal, enucleation, or lateralization of the canal contents, seem to be popular options. In a systematic review, success rates and expected complications of such treatments were evaluated.17) Implant success rates of these treatments varied between 84% and 100%, and reported complications, if any, ranged from transient to permanent sensory loss in the anterior maxillary area.17) In a report of 22 surgical cases involving the removal of NP canal soft tissue, sensory loss was seen in only 10% of cases.18) In our patient, seven months post treatment, the sensory loss to the anterior palate seems permanent but slight, and sub-consciously, not noticeable to the patient.

To maximize the regenerative potential of the grafting, the authors chose to utilize a bone sandwich layering technique described by others.19) The osteogenic capabilities of growth factors and autogenous bone, along with the longer-lasting shell of a xenograph, were used for greatest bone regeneration.

Despite the lack of adequate bone for the placement of implants often encountered in the maxillary central incisor location, the described technique can facilitate replacement of missing incisors. The presentation of this case report outlines the anatomic structures located within the NPC, the variations in dimensions that were noted, and the CBCT imaging required to predictably plan a case that involves the enucleation of the NPC, proper site development, and implant reconstruction in the anterior maxilla. Furthermore, when working in this area where precision is a must, the authors recommend the use of guided implant surgical techniques.

CONCLUSIONS

Due to the patient’s thin buccal plate and inadequate bone width for implant placement, obliteration of the nasopalatine canal with subsequent grafting was crucial for the success of replacing this maxillary central incisor. The use of CBCT planning and 3D surgical guide fabrication allowed for the guided, surgical placement of the implant in the ideal restorative-driven position. The authors believe this technique of nasopalatine canal obliteration and grafting is a viable option, yielding the ideal placement of dental implants in the maxillary central incisor area.

References
  1. Singhal MK, Dandriyal R, Aggarwal A, Agarwal A, Yadav S, Baranwal P. Implant placement into the nasopalatine foramen: considerations from anatomical and surgical point of view. Ann Maxillofac Surg 2018;8:347-51.
    Pubmed KoreaMed CrossRef
  2. Bra-nemark, Per-Ingvar, Zarb, George A., Albrektsson, Tomas, George A, Rosen, Harvey M. M.D., D.M.D. Tissue-Integrated prostheses. osseointegration in clinical dentistry. Plastic and Recon-structive Surgery 1986;77:496-7.
    CrossRef
  3. Rosenquist JB, Nyström E. Occlusion of the incisal canal with bone chips. A procedure to facilitate insertion of implants in the anterior maxilla. Int J Oral Maxillofac Surg 1992;21:210-1.
    Pubmed CrossRef
  4. Anatomical evaluation of nasopalatine canal on cone beam computed tomography images. Folia Morphol (Warsz) 2019;78:153-62.
  5. Friedrich RE, Laumann F, Zrnc T, Assaf AT. The nasopalatine canal in adults on cone beam computed tomograms-A clinical study and review of the literature. In Vivo 2015;29:467-86.
  6. Liang X, Jacobs R, Martens W, Hu Y, Adriaensens P, Quirynen M, Lambrichts I. Macro- and micro-anatomical, histological and computed tomography scan characterization of the nasopalatine canal. J Clin Periodontol 2009;36:598-603.
    Pubmed CrossRef
  7. Waasdorp J. Enucleation of the incisive canal for implant placement: a comprehensive literature review and case report. J Oral Implantol 2016;42:180-3.
    Pubmed CrossRef
  8. Bodereau EF, Flores VY, Naldini P, Torassa D, Tortolini P. Clinical evaluation of the nasopalatine canal in implant-prosthetic treatment: a pilot study. Dent J (Basel) 2020;8:30.
    Pubmed KoreaMed CrossRef
  9. Kobayashi Y, Kyo I, Satoh K, Isomura M, Urano M. Naso-palatine duct cyst occurring after secondary alveolar bone grafting: a case report. Oral Sci Int 2022;19:134-7.
    CrossRef
  10. Gaspar J., Gaspar R., Esteves T., Rua J., Alcoforado G., Mendes J.J. Implant placement in the nasopalatine canal for the rehabilitation of severely atrophic maxillae- case series with 1 to 5 years follow-up. Clin Oral Impl Res 2019;30:125.
    CrossRef
  11. Hamilton A, Vazouras K, Friedland B, Gallucci GO, De Souza A. Influence of implant diameter and taper on virtual implant placement in the maxillary central incisor position: a CBCT analysis. Int J Oral Maxillofac Implants 2022;37:525-32.
    Pubmed CrossRef
  12. Verardi S, Pastagia J. Obliteration of the nasopalatine canal in conjunction with horizontal ridge augmentation. Compend Contin Educ Dent 2012;33:116-20, 122.
  13. Mardinger O, Namani-Sadan N, Chaushu G, Schwartz-Arad D. Morphologic changes of the nasopalatine canal related to dental implantation: a radiologic study in different degrees of absorbed maxillae. J Periodontol 2008;79:1659-62.
    Pubmed CrossRef
  14. Waasdorp J. Enucleation of the incisive canal for implant placement: a comprehensive literature review and case report. J Oral Implantol 2016;42:180-3.
    Pubmed CrossRef
  15. Magennis P. Sensory morbidity after palatal flap surgery--fact or fiction? J Ir Dent Assoc 1990;36:60-1.
  16. Resnik R. Misch's Contemporary Implant Dentistry. Fourth Ed. Canada: Elsevier Inc.; 2021.
  17. De Mello JS, Faot F, Correa G, Júnior OC. Success rate and complications associated with dental implants in the incisive canal region: a systematic review. International journal of oral and maxillofacial surgery 2017;46:1584-91.
    Pubmed CrossRef
  18. Francoli JE, Marques NA, Aytes LB, Escoda CG. Nasopalatine duct cyst: report of 22 cases and review of the literature. Med Oral Patol Oral Cir Bucal 2008;13:e.
  19. Wang HL, Misch C, Neiva RF. "Sandwich" bone augmentation technique: rationale and report of pilot cases. International Journal of Periodontics & Restorative Dentistry 2004;24.


This Article

e-submission

Archives

Indexed/Covered by

  • renew
  • banner_koreatoothbank