|Year : 2020 | Volume
| Issue : 2 | Page : 96-102
Maxillary anterior cortical bone thickness: An imperative parameter for implant solidity - 3-dimensional cone beam CT study
Shalu Rai1, Deepankar Misra1, Mansi Khatri1, Tarun Vyas2, Poulomi Bhakta3, Priyank Mallick1
1 Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Kadrabad, Modinagar, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, R R Dental College and Hospital, Umarda, Udaipur, Rajasthan, India
3 Department of Oral Medicine and Radiology, Daswani Dental College and Research Centre, Rajasthan, India
|Date of Submission||17-Jan-2020|
|Date of Decision||06-Apr-2020|
|Date of Acceptance||19-Apr-2020|
|Date of Web Publication||27-Jun-2020|
Dr. Shalu Rai
Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Kadrabad, Modinagar - 201201, UP
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: This study aims to evaluate alveolar height, buccal, and palatal cortical bone thickness using cone beam computed tomography (CBCT) useful for radiological pre-assessment for various surgical procedures of maxillary anterior region. Materials and Methods: Maxillary central and lateral incisors and canines were bilaterally evaluated in 200 selected patients. Images were obtained with New Tom CBCT and traced with New Net Technologies software. Alveolar height and cortical bone thickness at 3 mm, 6 mm, and 9 mm above the cemetoenamel junction were measured and statistically analyzed. Results: Significant differences in alveolar height were found genderwise and agewise and were found to be highest in age groups of 51–60 years and lowest in 11–20 years. Buccal thickness at 3 mm, 6 mm, 9 mm was highest in right central incisor, right central incisor and left central incisor and lowest in right canine, left canine and left canine, respectively. Palatal thickness at 3 mm, 6 mm, 9 mm was highest in right central incisor, left central incisor and left central incisor and lowest in left canine, left canine, and left canine, respectively. Bucco-palatal thickness at 3 mm, 6 mm, 9 mm was highest in left canine, right central incisor and left central incisor and lowest in right lateral incisor, respectively. Agewise and genderwise significant differences in buccal and palatal bone were found at different levels. Conclusion: Buccal bone is thinner than palatal bone; thus, require careful radiological appraisal in orthodontic tooth movement and any surgical procedure in this region.
Keywords: Cone beam computed tomography, cortical bone thickness, orthodontic mini implant, orthodontic tooth movement
|How to cite this article:|
Rai S, Misra D, Khatri M, Vyas T, Bhakta P, Mallick P. Maxillary anterior cortical bone thickness: An imperative parameter for implant solidity - 3-dimensional cone beam CT study. J Indian Acad Oral Med Radiol 2020;32:96-102
|How to cite this URL:|
Rai S, Misra D, Khatri M, Vyas T, Bhakta P, Mallick P. Maxillary anterior cortical bone thickness: An imperative parameter for implant solidity - 3-dimensional cone beam CT study. J Indian Acad Oral Med Radiol [serial online] 2020 [cited 2020 Aug 6];32:96-102. Available from: http://www.jiaomr.in/text.asp?2020/32/2/96/288122
| Background|| |
Esthetics and exigent anatomy of maxillary anterior region makes it challenging for dentists to plan treatment in this area. Position of root and thin friable buccal plate are common hindrances. This has raised the need of maxillofacial radiology to obtain predictable positive treatment outcomes.,
However, key to success for any treatment plan depends upon the identification of landmarks and determination of alveolar height, density, and width of cortical bone by the dentist. Selection of a three dimensional imaging modality such as cone beam computed tomography (CBCT) furnishes a thorough pre-assessment for the same.,
The present study was undertaken to evaluate various parameters using CBCT in maxillary anterior teeth region to determine the success of implant placement and orthodontic tooth movement. It also determines genderwise and agewise differences in cortical bone thickness and alveolar height.
| Materials and Methods|| |
In this cross-sectional observational retrospective study 200 CBCT scans of maxillary anterior region were selected from the database of a diagnostic center in Delhi-NCR, as a part of dental implant pre assessment planning and patients who gave consent for CBCT scan and their usage for research purpose.
The study sample was divided into groups based on age group I: 11–20 years, group II: 21–30 years, group III: 31–40 years, group IV: 41–50 years, group V: 51–60 years, group VI: 61–70 years. Right and left maxillary anterior teeth including central incisor (11,21), lateral incisor (12,22), and canine (13,23) were selected for the study.
Linear measurements of alveolar bone were obtained for selected teeth, on labial/buccal, palatal, labiopalatal/bucco-palatal sides, using measurement tools by using CBCT software new net technologies (NNT) viewer software version 6.1, QR Sri Company, Verona, Italy. The inclusion criteria for selection of scans:
- Patients of both the sexes with age ranging from 11 to 70 years.
- Patients without any facial deformity.
- Only high-quality reconstructed images
All high resolution CBCT images were obtained by NewTomGiano unit (QR SRL Company, Verona, Italy) with a 8 × 5 cm field of view (FOV) and exposure parameters of kVp = 90, mAs = 14.64, exposure time = 3.6 s. The image acquisition protocol consisted of 360° rotation with an X-ray tube and a flat panel amorphous silicon detector. The CBCT volumes obtained were displayed with a 0.250-mm thickness.
The images obtained in DICOM format were transferred to a separate workstation and the measurements were done in a quiet windowless room with proper lighting. The images were viewed on HP Envy Spectre X360 Convertible 13 –ac059tu, 13.3 inch diagonal HD bright view LED-backlit display, Core i7 7500U processor (Hewlett-Packard Company, 71004 Boeblingen, Germany) at a 1920 × 1080 resolution and measurements were done in axial and coronal cross section views.
The alveolar height: from midpoint of cementoenamel junction (CEJ) of the respective tooth to the most inferior point of nasal fossa along the long axis of the tooth in sagittal section [Figure 1], labial, palatal, and labio-palatal cortical bone thickness in axial section at 3 mm above CEJ were measured for selected teeth [Figure 2], Same was repeated at 6 mm and at 9 mm. To increase the success rate of implant it is empirical to measure the cortical bone thickness at different levels, hence, these measurements were chosen.
|Figure 1: Multiplanar reformation (MPR) image of cone beam computed tomography (CBCT) showing alveolar height measurement|
Click here to view
Labial cortical bone thickness was measured from the labial/buccal limit of radicular contour up to the outermost section of cortical bone, perpendicular to the contour of the dental arch (POINT A). Palatal cortical bone thickness was measured from palatal limit of the radicular contour up to the outermost section of cortical bone, perpendicular to the contour of the dental arch (POINT B). Labio-palatal/bucco-palatal cortical bone thickness was measured from POINT A to POINT B, which is outermost section of cortical bone labially to outermost section of cortical bone palatally perpendicular to the contour of the dental arch.
All images were evaluated by two experienced maxillofacial radiologists and were observers for the study. The observers were blinded to the details of age and sex of the subjects. All measurements were taken twice by the same observer and the mean values of all the measurements were included in the statistical analysis. The observers performed the study twice with an interval of three weeks to detect intraobserver variability.
Data were entered into SPSS software (version 19.0) and were statistically analyzed by Chi-Square test with 5% level of significance. Independent “t”-test, Mann-Whitney U test, ANNOVA test, and Kruskal-Wallis H test have been used to find the significance of study parameters on ordinal scale between two or more than two groups. Intra- and interexaminer validation measures were conducted. To assess intraobserver reliability, the Wilcoxon-matched pairs signed rank test was used. The inter observer reliability was determined by the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) [CV = (standard deviation/mean) × 100%]. ICC values range from 0 to 1. ICC values greater than 0.75 showed good reliability and the low CV demonstrates the precision error as an indicator for reproducibility.
| Results|| |
A total of 200 scans were analyzed, out of which 111 were of males and 89 were of females.
The mean alveolar height at tooth no #21 was 17.512 ± 3.272, at tooth no #22 was 18.826 ± 4.152, at tooth no #23 was 21.538 ± 3.798, tooth no #11 was 17.139 ± 3.222, at tooth no #12 was 18.238 ± 3.689, at tooth no #13 was 21.677 ± 3.677.
Genderwise comparison of alveolar height was more in males and the differences were statistically significant [Table 1]
Genderwise comparison of Buccal thickness, Palatal thickness and Buccopalatal thickness at 3mm,6mm, 9mm between different teeth is described in [Table 2].
Agewise comparison of alveolar height was highest in age group 51–60 years and lowest in 11–20 years and the differences for tooth no #21, 22, 23, 12,13 were statistically significant. (P value = 0.025, <0.001, <0.001, 0.001, 0.003, respectively) [Table 3].
Agewise comparison for tooth no #11,21
At 3 mm buccal and palatal thickness was maximum in 11–20 years for both sides and minimum in >60 years and in 41–50 years on both sides. Buccopalatal thickness was maximum in 11–20 years and minimum in 41–50 years on right side and in >60 years on left side. [Table 4].
At 6 mm buccal thickness was maximum in 11–20 years on both sides and minimum in >60 years on left side and in 31–40 years on right side. Palatal thickness was maximum in 11–20 years on left side and in 31–40 years on right side and minimum in 41–50 years on both sides. Buccopalatal thickness was maximum in 11–20 years and minimum in 41–50 years on both sides. [Table 4].
At 9 mm Buccal thickness was maximum in 11–20 years and minimum in 41–50 years [Table 4].
Agewise comparison for tooth no #12,22
Agewise comparison of Buccal thickness, Palatal thickness and Buccopalatal thickness at 3mm, 6mm, 9mm between different teeth is described in [Table 4].
| Discussion|| |
Implant stability in maxillary anterior region depends upon overlying soft tissues which is guaranteed by bone availability in all dimensions., Compared to the palatal bone, the labial plate is thinner and resorption after extraction occurs more easily and severely owing to its composition of bundle bone.
The stabilization and long-term success of dental implants depends largely on the thickness of buccal bone. In the treatment of apical pathosis where surgical intervention is planned, the prognosis is directly related to bone and soft tissue thickness in the operated region., Also in cases of orthodontic mini implants, the crucial factor for the stabilization is bone thickness.
This study describes mean alveolar height to be highest at right canine (21.677 ± 3.677) and lowest at right central incisor (17.139 ± 3.222). The mean labial or buccal wall, palatal wall, and overall bucco-palatal thicknesses were observed at 3 mm, 6 mm, and 9 mm for both incisors and canines of right and left side.
In our study, the mean buccal thickness at 3 mm was highest at Right Central Incisor (0.187 ± 0.485) and lowest at right canine (0.070 ± 0.335), at 6 mm was highest at right central incisor (0.664 ± 0.701) and lowest at left canine (0.352 ± 0.713), at 9 mm was highest at left central incisor (0.818 ± 0.902) and lowest at right canine (0.279 ± 0.532). The findings were similar to previously described values of buccal thickness by Huynh-Ba et al. (2010) who concluded that the mean width of the buccal bony wall was 0.8 mm. 87% of the buccal bony walls had a width < or = 1 mm and 3% of the walls were 2 mm wide. However, Vera et al. (2012) in their study concluded that very few maxillary teeth displayed buccal alveolar bone thickness greater than 1 mm. Similar findings were reported by Tomasi et al. (2010) who determined that the dimension of buccal plate of bone was a major factor affecting the degree of resorption and with buccal bone more than 1 mm was present in only few patients. Januário et al. (2011) in his study found thickness of buccal plate varied from 0.5 to 0.7 mm. Ghassemian et al. (2012) values were comparable with the values found in this study.
In our study, the mean palatal thickness at 3 mm was highest at right central incisor (2.079 ± 1.571) and lowest at left canine (0.804 ± 1.205), at 6 mm was highest at left central incisor (3.895 ± 2.241) and lowest at left canine (2.240 ± 1.360), at 9 mm was highest at right central incisor (6.266 ± 2.508) and lowest at left canine (3.854 ± 1.773). Similarly, the mean bucco-palatal thickness at 3 mm was highest at left canine (8.893 ± 1.458) and lowest at right lateral incisor (7.496 ± 1.769), at 6 mm was highest at right central incisor (9.710 ± 2.186) and lowest at right lateral incisor (8.502 ± 1.588), at 9 mm was highest at left central incisor (10.651 ± 2.741) and lowest at right lateral incisor (8.680 ± 2.115). Individual studies determining importance of palatal thickness and bucco-palatal thickness could not be established however, Younes et al. (2016) found a positive correlation between the bucco-palatal thickness and soft tissue, in determination of prognosis of implant.
In our study, genderwise comparison of alveolar height was more in males except for left central incisor where it was more in females. No reason for this reverse sexual dimorphism could be established in our study or from the literature. Agewise comparison of alveolar height in our study showed mean alveolar height was highest in age group 51–60 years and minimum in 11–20 years suggesting phenomenon of bone loss after 60 years of age. Similar results were found by Alsaffar et al. (2016).
Genderwise comparison of bone thickness in our study revealed that thicker buccal and palatal cortical bones were found in males at different levels in different teeth. The results were in accordance with the findings of Abbas et al. (2017), Ono et al. (2008), but contrary to those of Deguchi et al. (2006). This may be due to differences in sampling and measurement methods taken by Deguchi et al. (2006).
Alsaffar et al. (2016) in their study found out no significant difference between both genders regarding the thickness of alveolar bone at the alveolar crest, the middle of the root and at the apical one third. This could be explained by reports which confirm that periodontal diseases are more common in men. Similar results were obtained by Shiau and Reynalds (2010), Cassetta et al. (2013), and Sawada et al.(2013), Park et al.(2013), and Lee et al. (2010) where remarkably thin bone (approximately 0.1–0.6 mm) was reported around the canine in comparison to the central and lateral incisors.
Agewise comparison of buccal bone thickness at 3 mm, 6 mm, and 9 mm in our study revealed statistically significant differences of right and left central and lateral incisors, however for canine statistically significant differences were found for right canine at 3 mm and left canine at 9 mm. Palatal bone thickness at 3 mm, 6 mm, and 9 mm revealed statistically significant differences of right and left both incisors and canines at 3 mm and 6 mm. Bucco- palatal thickness at 3 mm, 6 mm for both right and left incisors and canines had statistically significant differences. However, at 9 mm only left lateral incisor had statistically significant differences. Similar findings were reported by Kim et al. (2016) and Zohu et al. (2014) who determined differences in bone thickness at different levels in different age groups and concluded thickness of bone decreases with advancing age.,
Therefore to protect the frail labial bone and avoid severe marginal recession, the position of implant should be more palatally in the alveolar bone as compared to the primary tooth root except in case of canine. Thus, in cases with thin buccal bone walls, clinicians must consider the use of bone grafts to preserve the three-dimensional anatomy of this complex region without compromising the aesthetic results.
To summarize, the present study concluded that the alveolar cortical bone is thicker in males than females and more on palatal side than buccal or labial side. There is a significant linear increase of thickness from crest to base of alveolar crest. Adults show a thicker alveolar cortical bone than adolescents.
| Conclusion|| |
The results of this study may provide insight on the usefulness of CBCT in providing a base line data for selecting the appropriate site for implant placement in terms of alveolar height. CBCT enables accurate measurement of bone quality and quantity along with measuring the distance from anatomic structures, due to its three-dimensional nature. CBCT proves to be a valuable diagnostic aid in pre implant radiological assessment.
Scientific recommendations and unique observation
Iatrogenic risk of tooth movement or implant insertion beyond alveolar bone limits may adversely affect treatment outcome. Buccal and palatal cortical plates are favorable for the success of the implant stability and prognosis. Meticulous analysis of the anterior maxillary region is essential before placement of any implant, orthodontic tooth movement or anchorage mechanics as thickness of buccal and palatal bone vary at different tooth locations. However, palatal aspect constitutes a preferred site due to comparatively thicker bone. Clinicians must be aware of implant site and a proper site preparation if required must be accomplished prior to the procedure. CBCT is an essential pre assessment tool and provides three-dimensional images of bone.
We thank Dr. Mohit Dadu for the efforts in statistical analysis.
This study was conducted under the approval of institutions ethical committee and Reference Number: CTRI/2017/11/010412.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]