|Year : 2014 | Volume
| Issue : 3 | Page : 197-201
Anatomic and anaesthetic considerations of greater palatine nerve block in Indian population
Nidhi Sharma1, Rohit Varshney2, Sudhakar Ray1
1 Department of Anatomy, Teerthankar Mahaveer Medical College, Moradabad, Uttar Pradesh, India
2 Department of Anaesthesia, Teerthankar Mahaveer Medical College, Moradabad, Uttar Pradesh, India
|Date of Web Publication||11-Oct-2014|
Department of Anaesthesia, Teerthankar Mahaveer Medical College, Delhi Road, Moradabad, Uttar Pradesh - 244 001
Background: Greater palatine nerve block holds its importance for anaesthesia and analgesia in different maxillofacial surgical procedures. Accuracy in localization of greater palatine foramen is required for its successful implication in regional block, although racial variations exist in various population groups.
Aims: To study the morphometry of greater palatine foramen and its location with nearby anatomical landmarks in Indian population.
Material and Methods: A total of one hundred dry skulls (60 males and 40 females) were collected and observed for the study. Various parameters were noted from greater palatine foramen on both sides, together with its location with respect to maxillary molar tooth. Along with that the angle between midline maxillary suture and Incisive foramen-Greater palatine foramen is measured.
Results: 198 sides were measured and the most common location of greater palatine foramen was found to be medial to third molar tooth (71.21%). The mean distance from greater palatine foramen to midline maxillary suture on right and left sides were 14.82 ± 1.34 mm and 14.79 ± 1.57 mm, statistically insignificant. The angle between midline maxillary suture and incisive foramen-greater palatine foramen was 20.81° ± 2.47°on right side and 20.58° ± 2.69°on left side.The direction of the opening of greater palatine canal onto the hard palate was observed to be antero-medial in 60.10% of cases.
Conclusions: Our study reveals the importance of usage of various anatomical parameters for precise location of greater palatine foramen, establishment of specific measurements in each population group and thereby applying such measurements for successful greater palatine nerve block.
ملخص البحث :
تهدف هذه الدراسة لقياس أشكال الثقبة الحنكية الكبرى وموقعها بالنسبة للمعالم التشريحية القريبة لدى الهنود. وتمت الدراسة على مائة جمجمة لستين رجلا واربعين إمرأة بمعايير مختلفة من الثقبة الحنكية الكبرى بطرفي الجمجمة. وضحت الدراسة أهمية استخدام المعايير المختلفة لتحديد موقع الثقبة الحنكية الكبرى بصورة دقيقة وتحديد قياسات محددة لكل مجموعة سكانية ومن ثم استخدام هذه القياسات لتخدير العصب الحنكي الأكبر.
Keywords: Greater palatine foramen, greater palatine nerve block, morphometry
|How to cite this article:|
Sharma N, Varshney R, Ray S. Anatomic and anaesthetic considerations of greater palatine nerve block in Indian population. Saudi J Med Med Sci 2014;2:197-201
|How to cite this URL:|
Sharma N, Varshney R, Ray S. Anatomic and anaesthetic considerations of greater palatine nerve block in Indian population. Saudi J Med Med Sci [serial online] 2014 [cited 2020 Jun 2];2:197-201. Available from: http://www.sjmms.net/text.asp?2014/2/3/197/142548
| Introduction|| |
The greater palatine nerve is a branch of maxillary nerve, emerging from greater palatine foramen (GPF) and supplying the mucous membrane of hard palate, postero-inferior part of lateral wall of nose and medial wall of maxillary sinus.
The greater palatine nerve block is commonly used for local anaesthesia in different maxillofacial and dental procedures.  Two extensively used techniques for intraoral greater palatine nerve block had been described in literature (high tuberosity/greater palatine canal approach). Considering the prospects of safety and ease of applicability greater palatine approach is more commonly practiced. 
The greater palatine nerve block is commonly employed for anaesthetising hard palatal tissue distal to the canines and medial to midline. It is a more suitable technique for providing analgesia in patients undergoing palatal surgeries as compared to opioids which are associated with various side effects.  However, difficulty in exact localization of GPF leads to inability in obtaining adequate anaesthesia and analgesia. 
Extensive medline search revealed different landmarks for the specific location of GPF. Hamilton  described its location near the posterior border of hard palate medial to posterior alveolus, Ferreria  depicted its position in the hard palate at the level of the dihedral angle (formed by the horizontal lamina of the palatine bone and the inner surface of the maxillary alveolar process) and Rizzolo and Madeira  advocated its presence at the posterolateral angle of the palatine bone, next to the last molar tooth. Moreover, the 2nd molar tooth is an unstable reference point of GPF among different races and in conditions like periodontitis. ,,
Limited literature availability for localization of appropriate position of GPF in Indian maxilla together with marked racial variation raises the idea behind the aim of our study to evaluate the location and direction of the opening of GPF into the oral cavity in dry adult Indian skulls.
| Materials and methods|| |
A total of one hundred dry skulls (60 males and 40 females) collected from medical and dental colleges of Teerthanke Mahaveer University, India, were used for the study. We excluded all child skulls and the skulls with damaged hard palate/greater palatine canal.
The following parameters were measured [Figure1]:
|Figure 1: Hard palate. IF – Incisive foramen; GPF – Greater palatine foramen; MMS – Midline maxillary suture; PBHD – Posterior border of hard palate; M2 – Maxillary second molar; M3 – Maxillary third molar; A – Angle between the MMS and the line from the IF and the GPF|
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- Location of the GPF in relation to maxillary molar tooth;
- The center of the GPF to the midline maxillary suture (MMS);
- The center of the GPF to the posterior border of hard palate (PBHP);
- Distance from the center of the GPF to the posterior border of the incisive foramen (IF);
- Direction of opening of the GPF into the oral cavity;
- Angle between the MMS and line joining the IF with GPF.
The measurements related to GPF were taken with double tipped compass and then transferred to verniercalipers (least count 0.01 mm) to measure the distances. The dimensions were taken three times by the same person and mean was taken, thus increasing the accuracy of the data.The direction of the opening of GPF into the oral cavity was determined with the help of 25 G spinal needle. All measurements were done bilaterally and directly on the dry skulls. The angle between the MMS and the line from the IF and the GPF were measured and calculated on digital photographs using the Vista Metrix software (Skill Crest, Version 1.38, 2012).
Statistical Analysis: Mean ± standard deviation [mean ± SD], median and range were calculated. Student's t-test was used for paired and independent samples. Data analysis was done by using Statistical Package for Social Sciences (SPSS) version 19 and P-value < 0.05 was considered statistically significant.
| Results|| |
The total number skulls examined was: 100 [198 sides] were males and 40 were females 60
The number of sides not examined due to destruction: Right-0, Left-2
So the total number of slides examined was 198.
Greater palatine foramen was observed in all the studied skulls.
Most common location of GPF was found to be in line with third molar tooth with the incidence of 71.21% followed by the position between second and third molar tooth in 49% of skulls. However the presence of GPF behind the third molar tooth in 8% skulls was the rarest location. No foramen was found opposite to second molar tooth [Table 1].
The dimensions of GPF and its linear relationship with surrounding anatomical landmarks on skull were summarized in [Table 2]. The mean distance from GPF to MMS was 14.82 ±1.34 mm on right side and 14.79 ± 1.57 mm on left side. The minimum distance from GPF to MMS recorded was 13.12 mm and maximum was 15.51 mm. The mean distances between GPF-IF on right and left sides (37.74 ± 2.39 and 37.89 ± 2.83) mm and GPF-PBHP on right and left sides (4.39 ± 1.73 and 4.53 ± 1.23) mm. However, no statistical significance was observed among any of the above mentioned dimensions [Table 2].
|Table 2: Distances from GPF to MMS/IF/PBHP and angle between the MMS and the line from the IF and GPF|
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The angle between MMS and IF-GPF was statistically insignificant between both sides (20.81° ± 2.47°on right side and 20.58° ± 2.69°on left side) with the maximum value of 22.03° and minimum value of 18.73° [Table 2].
Anteromedial and anterior direction of the opening of greater palatine canal onto the hard palate was observed in 60.10% and 31.81% of cases. Vertical opening of GPFin oral cavity was not found in any of the skulls examined [Table 3].
| Discussion|| |
In our study, 95.96% of GPF were located medially and antero-medially to third maxillary molar tooth. Ajmani et al,  Saralaya and Nayak  and Sujatha et al.,  observed the location of GPF in Indian skulls adjacent to third and second-third maxillary molar tooth in 97.14, 98.80 and89.10% cases, respectively. Similar locations of GPF were encountered in the skulls of most of the cases by different investigators among various ethnic groups (Nigerian, Brazilian, Chinese, Greek, Iraq and Kenyan). ,,,,, In Brazilian skulls,  GPF was located distal to third molar in 38.94% cases while we observed it in only 4.04% of cases. Location of GPF at the lingual side of second molar was not found in any of our case but Ajmani et al.,  observed the same in 17% of Nigerian skulls. The above data from different population groups reveal that wide variability was seen for accurate location of GPF. The importance of accurate localization of GPF not only curtails down the possibilities of failed nerve blocks but also decreases the number of pricks which adds up suffering to the patient.
Chrcanovic et al.,  observed the distance between GPF-MMS as 14.68 ± 1.56 mm and 14.44 ± 1.43 mm on the right and left sides respectively. In Indian skulls, Ajmani et al.,  observed the distance of 14.7 and 14.6 mm on the right and left sides and Saralaya and Nayak  found the same dimension as 14.7 mm on both sides. Jafar and Hamadah  observed the distance as 15.7 mm in Iraqian skulls while in case of Thais  the mean dimension goes up to 16.2 mms. Although we also observed wide variations in the distance between GPF-MMS (13.12-15.51) mm but the mean distance on right and left side as 14.82 ± 1.34 mm and 14.79 ± 1.57 mm, respectively (P = 0.89) which was less than other ethnic populations. The fluctuating dimensions among different inhabitants could be attributed due to embryological factors of variable sutural growth occurring between the maxilla and palatine bone. 
The distance between GPF-PBHP holds its importance for successful localization of GPF and preventing accidental injury to nearby lesser palatine nerves and soft palate. Moreover, this dimension also helps in localization of GPF in those cases where third molar tooth failed to erupt or damaged due to any reason. In our study, the mean distance between GPF-PBHP on right and left sides was 4.39 ± 1.73 mm and 4.53 ± 1.23 mm (P = 0.51), respectively, ranging from 2.79-8.10 mm. Wide variations were observed in the distance between GPF-PBHP among different sub-groups with both greater , and smaller dimensions ,,,, compared to our study, again justifying the racial possibility behind them.
Chrcanovic et al.,  found the mean angle in Brazilian skulls to be 22.12° and 23.30° on right and left sides, respectively. To our best of literature search, only Saralaya and Nayak  observed such an angle (right = 21.1°; left = 21.2°) in Indian skulls. We observed the mean angle between MMS and the line joining IF to GPF on right and left sides as 20.81° ± 2.47°and 20.58° ± 2.69° (P = 0.53) respectively, ranging from 18.73° - 21.25°. Furthermore, the distance between GPF-IF in right and left sides (37.74 ± 2.39 and 37.89 ± 2.83; P = 0.68) mm in our study with minimum to maximum being 35.67 mm-42.12 mm. Smaller dimensions between GPF-IF were observed by Chrcanovic et al.,  and Saralaya and Nayak  in Brazilian and Indian skulls, respectively. The possible reason behind smaller diameter arises from the fact that they took the measurement scale from the anterior wall of the GPF to the posterior border of the IF compared to our study where we had taken dimensions from the center of foramina. They also witnessed a wide range in the measurements advocating its high margin of variability. The determination of the angle and the distance between GPF-IF is important for medical professionals in directing the needle for precise infiltration of local anaesthetics to GPF. Moreover, the diameter between GPF-IF is also helpful in determining the site of GPF in conditions with absent molar tooth and patients with midline palatal defects creating difficulty in locating MMS.
In our study, the direction of greater palatine canal on the hard palate was observed antero-medially in 60.10% of skulls. The same direction of greater palatine canal as our study was also observed by other investigators in Indian skulls. ,, However, in case of Brazilian  and Chinese  skulls the anterior direction of opening of greater palatine canal is more commonly encountered. The direction of opening of greater palatine canal helps in proper introduction of the needle into the foramen and gives an idea for the path to be traced up into the greater palatine canal. The variation in different ethnic populations leads us to think a possible cause behind the difficulty encountered during admitting the needle into the GPF.
The present study provides valuable information for the location of GPF with respect to the surrounding anatomical landmarks in adult Indian skulls. These linear dimensions will prove to be helpful on living subjects in anaesthetic and surgical procedures and thereby preventing the dreadful complications. Our findings also emphasize on the ethnic variations in the occurrence of GPF as supported by other studies. Similar kind of work was done in the past by other Indian authors but they did not measure the angle between GPF-IF in their study. , However, Saralaya and Nayak  observed the same but the methodology of estimating the angle between GPF to midline was not explained by them. Moreover, Saralaya and Nayak  measured the angle from anterior border GPF in their study which is questionable due to variations in the shapes of GPF , but we took measurements from the center of the foramina. We consider that the diversity could be a result of factors such as age, sex, race and differences in the reference points which are taken as criteria in the measurements. The wide variability in locating the position of GPF among different population groups warrants the need for studies from different regions of the world.
| Conclusion|| |
This study helps to determine the precise location and direction of the GPF (by the angle formed between MMS and line joining GPF-IF) in relation to various anatomical structures, in Indian population. The landmarks described could be identified and effectively applied with success in various clinical scenarios, thereby decreasing the risk of failures and complications.
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[Table 1], [Table 2], [Table 3]