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ORIGINAL ARTICLE
Year : 2021 | Volume
: 24
| Issue : 3 | Page : 329-334
Evaluation of facial and palatal alveolar bone thickness and sagittal root position of maxillary anterior teeth on cone beam computerized tomograms
P Soumya1, V Chappidi2, P Koppolu3, KR Pathakota4
1 Department of Dentistry, Mahaveer Medical College and Hospital, Vikarabad, Telangana, India
2 Department of Oral Medicine and Radiology, Sri Sai College of Dental Surgery, Vikarabad, Telangana, India
3 Department of Preventive Dental Sciences, College of Dentistry, Dar Al Uloom University, Riyadh, KSA
4 Periodontics, Sri Sai College of Dental Surgery, Vikarabad, Telangana, India
Correspondence Address:
Dr. P Koppolu
Department of Preventive Dental Sciences, College of Dentistry, Dar Al Uloom University, Riyadh
KSA
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/njcp.njcp_318_20
Abstract
Background: Amount of bone covering the facial and palatal surface of the root and the sagittal root position are important parameters while considering an immediate implant placement. Aims: This study measures the distance from cement-enamel junction (CEJ) to alveolar crest and thickness of alveolar bone of maxillary anterior teeth facially and palatally at 5 different points. Materials and Methods: CBCT scans of 79 systemically healthy patients were evaluated by two calibrated and independent examiners. Measurements like: 1) distance from CEJ to Crest. 2) Thickness of facial and palatal alveolar bone at five different points a) Crest, b) 2 mm from the crest, c) mid root level, d) apical 3rd, e) apex. 3) Sagittal root position. 4) Labiopalatal distance at the apex. 5) Length of the bone from apex to the nasal floor for incisors. 6) Presence of fenestrations and dehiscences were assessed. Results: Healthy maxillary anteriors were evaluated and less than 2 mm bone was seen at all five points, 0.5 to 1 mm bone is seen in all anteriors at crest, 2 mm from crest, midroot, apical 3rd level. 1 to 2 mm is seen at apex. Labiopalatal width at apex ranged from 3 mm to 13 mm with a mean of 7.45 ± 2.24 mm for centrals, 7.69 ± 2.14 mm for lateral incisors, and 6.76 ± 2.42 mm for canines. Conclusion: The present study supports the finding of very thin facial bone over maxillary anteriors and frequent occurrence of fenestrations and dehiscences. Pre-treatment evaluation of alveolar bone surrounding the maxillary anteriors is important to avoid complications during implant placement.
Keywords: Alveolar bone thickness, cone beam computerized tomography, cortical plate, dehiscence, fenestration
Introduction 
Immediate implant placement after tooth extraction has become a common practice in recent years. It has several advantages that it reduces the waiting period between tooth removal and prosthetic replacement, shorter treatment time, less psychological stress and improved esthetics of the patient.
Immediate implant placement in anterior maxilla is a very difficult treatment procedure due to esthetic, phonetic, biomechanical and anatomical considerations. There arises a difficulty in predicting the thickness of facial alveolar bone without proper radiological aid. Presence of thin facial bone or a prominent root position may contribute to facial bone fenestration, dehiscence and soft tissue recession after implant placement.[1],[2],[3] Factors like presence of an intact bony socket following extraction and the absence of active infection influence success rates of immediate implant placement. Primary implant stability must be achieved by engaging the implant with the palatal wall and the bone approximately 4-5 mm beyond the root apex.[4],[5]
Careful evaluation of orofacial ridge anatomy using clinically sound and sophisticated radiographic techniques like cone beam computerized tomography (CBCT) can help in diagnosing the defects like facial bone atrophy. CBCT is a non-invasive radiographic technique which has a high resolution, low dose of radiation, offers financial advantage for the patient and allows full 3D characterization of alveolar bone.
There is scarcity of data reporting the initial thickness of facial and palatal alveolar bone, length of bone beyond the apex, sagittal root position and width of bone at the apex in maxillary anteriors especially with regards to the Indian population. The purpose of this present study is to evaluate the thickness of facial and palatal alveolar bone of maxillary anterior teeth and to determine the frequency of fenestrations and dehiscence's occurring in these teeth.
Methods Hundred systemically healthy dentulous and/or partially edentulous patients (53 males and 47 females) aged between 17-72 years (with a mean age of 42.7 years) scheduled for implant insertion in different dental clinics in Hyderabad were included in the study. Written informed consent was obtained from all the patients, this study was conducted in Sri Sai College of Dental Surgery and the ethical committee of the institute approved this study.
The subjects met the following inclusion criteria;
Patients with intact maxillary anteriors.No history of periodontal disease or bone loss in upper anterior region.No improper tooth alignment.The exclusion criteria were
The presence of any restorations, root canal treatment and bridges.CBCT with scattered images.21 patients were excluded from the study as they did not meet the criteria.
All CBCT scans were obtained with 1 mm slice thickness and the tomographic scanner (mm field of view, kV, mAs, pitch of mm). A software program (CS 3D Imaging software) was used to reconstruct the images and perform the measurements.
Two observers were calibrated using 10 randomly selected scans. An assessment of the reproducibility of measurement between observers measuring the same quantity to one-tenth of a millimetre was calculated at a correlation of 0.95 for the 10 scans. Each of the two observers measured 79 scans independently at the exact same slice and magnification.
Measurements were taken for the 6 maxillary anterior teeth.
Distance from CEJ to Crest.Thickness of facial and palatal alveolar bone at,Crest.2 mm from the crest.Mid root level.Apical 3rd.Apex.Labiopalatal width of bone at the apex.Length of the bone from root apex to the nasal floor for incisors.Sagittal root position.Fenestrations and dehiscences.Statistical analysis
Mean and standard deviations (SD) were calculated for all the variables. All statistical analysis was performed using SPSS version 19.0. Independent sample t test was used to compare all the parameters between males and female subjects. Analysis of variance (ANOVA) was used to evaluate the influence of age on the thickness of alveolar bone. A P value < 0.05 was considered to be statistically significant.
Results Initially CBCT scans of 100 patients were assessed, of which 21 were excluded. A total of 79 scans were evaluated for the determined parameters. Mean CEJ to bone crest distance varied among different individuals and also among different teeth. Mean CEJ to bone crest distances of maxillary anterior teeth were presented in [Table 1].
Thickness of alveolar bone facially and palatally was measured at five different points [Figure 1] and mean alveolar bone thickness of anterior teeth labially and palatally at crest, 2 mm from crest, mid root level, apical third and apex were presented in [Table 2].
Labial alveolar bone thickness
Anteriorly for central incisors less than 1 mm alveolar bone thickness was found for at crest, 2 mm from crest, mid root and apical third level, whereas at apex 1-2 mm thickness was found and lateral incisors were found to have less than 1 mm alveolar bone thickness at all five points, canines had less than 1 mm bone at crest and 2 mm from crest level, which was further reduced to less than 0.5 mm at mid root and apical third level, the decrease was due to increase in root diameter, at apex 1-2 mm thickness of alveolar bone was found.
Palatal alveolar bone thickness
Palatally central incisors, lateral incisors and canines were found to have 1-2 mm bone thickness at crest and 2 mm from crest, >2 mm alveolar bone thickness was noticed at mid root, apical third and apex levels.
When males and females were compared a statistically significant difference in thickness of alveolar bone was noticed palatally.
Labiopalatal width of alveolar bone at apex
Apically width of the bone ranged from 4.5 mm to 13 mm with a mean of 7.45 ± 2.24 mm for central incisors, for lateral incisors the mean width of bone at apex was 7.69 ± 2.14 mm (3.7-13.6 mm), canines had a width of 3 mm to 13.2 mm with a mean of 6.76 ± 2.42 mm. [Table 3], [Figure 2].
Figure 2: Labio-palatal width at apex and distance from apex to nasal floorDistance from tooth apex-nasal floor
Roots of centrals are found to be in close proximity to nasal floor, followed by canines and laterals. Distance from root apex to nasal floor for central incisors ranged between 1.1-10.3 mm with a mean of 7.88 ± 2.83 mm, apical to canines bone length ranged from 1.9-12.2 mm with a mean of 6.46 ± 2.72 mm [Table 4].
Sagittal root position
Sagittal root position in relation to osseous housing was analysed for all anteriors and divided into four classes [Figure 3]. Maximum teeth were presented with class I SRP, followed by class IV, class II and Class III. Central incisors presented with 86.5%, 5%, 0.5%, and 8% respectively of class I, II, III, IV. The lateral incisors presented with 76.5%, 8.5%, 1.5% and 14% respectively. The canines presented with 81%, 6%, 0% and 13% respectively [Table 5].
Fenestrations and dehiscence
Fenestrations and dehiscence were commonly reported in anterior teeth, in the present study highest number of fenestrations [Figure 4] was reported in lateral incisors followed by canines and central incisors. Occurrence of dehiscence [Figure 3] was mostly found in canines followed by centrals and laterals.
Discussion Regardless of the implant system used the placement of implant in a correct three dimensional position is an important factor in the esthetic outcome of the implant. Long-term stability of the implant depends on various factors; presence of gingival margins over the implant in harmony to the adjacent tooth is one of the important factors which mainly depend on the thickness of alveolar bone.[6],[7]
Studies suggested that the thickness of alveolar bone should be at least 2 mm to ensure proper soft tissue support and to avoid resorption following restoration.[5] Mean alveolar bone resorption was significantly increased when thickness was less than 2 mm, when compared to those with wider bone.[4] There was no statistically significant difference in implant failure rate when mean bone thickness was 1 mm, 1-2 mm whereas failure rates were significantly reduced when initial bone thickness was >2 mm.[8],[9]
The level of alveolar crest with respect to CEJ is an important parameter to consider while placing an implant; many studies suggested that the head of the implant should be located within 2-3 mm from the CEJ of adjacent teeth.[10],[11],[12] In the present study distance between CEJ to the bone crest was found to be 3-4 mm for incisors, whereas canines had greater CEJ to crest distance (>4 mm). This is in accordance with Vera et al.[13] who found CEJ to crest distance was 2.79 mm for maxillary anteriors. Similarly Wang et al.[14] reported a distance of 0.1 mm to 4 mm.
The present radiographic study evaluated the thickness of alveolar bone labially and palatally in maxillary anteriors and found occurrence of very thin labial plate anteriorly. This study found less than 2 mm alveolar bone at all five points (crest, 2 mm from crest, midroot level, apical third, apex) in all the maxillary anteriors and further supports the fact that implant should be inclined palatally. The findings of the present study are in accordance with Nowzari et al.,[15] who measured thickness of aveloar bone at five different points and found occurrence of thin labial plate. Similarly, Januario et al.[16] found occurrence of less than 1 mm bone in maxillary anteriors at 1, 3,5 mm from crest. Zekry et al.[17] reported mean width of 0.9 mm in maxillary anteriors. In a similar study, Feuntes et al.[18] reported less than 10% sites with more than 2 mm thickness. Recently Farahamnd et al.[19] found similar findings in maxillary anteriors. When centrals, laterals and canines were compared lateral incisors found to have a thicker labial plate when compared to central incisors and canines, this was due to the reduced root diameter of lateral incisors these findings are in accordance with Ghassemian et al.[20] in the present study canines had less than 0.5 mm bone at mid root level this was due to greater diameter of root at this level.
When the influence of gender on thickness of facial and palatal alveolar bone thickness was analysed a statistically significant difference was found with respect to the palatal alveolar bone. This finding was in contrast to the findings of Nowzari et al.[15] Braut et al.,[5] where they have not found any significant difference in thickness of alveolar bone between males and females.
In case of immediate implant placement, the labio-palatal width of the bone at the root apex is an important parameter to consider as extension of implant beyond the apex is indicated for increased primary stability and proper initial alignment.[21],[22] In case of thin bone width at apex there are chances of labial wall perforation, therefore prior analysis of width of bone at apex is needed in immediate implant cases. In our study, the labiopalatal width at the apex was found to be ranging from 3-12 mm.
In the present study central incisors and canines were found to be in close proximity to the nasal floor compared to the lateral incisors. Distance from apex to nasal floor ranged from 1-10 mm. These findings suggest greater chances of perforating nasal floor during immediate implant placement in maxillary anterior region.
Sagittal root position was classified into 4 classes: (i) Class I – root positioned against labial cortical plate (ii) class II – root is positioned in the middle of cortical plates without engaging labial or palatal cortical plate (iii) Class III – root positioned against palatal cortical plate (iv) Class IV – 2/3rds of root engages both labial and palatal cortical plates.[23] In the current study Class I SRP was frequently observed in anteriors. Khoury et al.[24] in their study assessed SRP and its relation to alveolar bone thickness and found class IV SRP with thinnest facial bone.
Conclusion The present study supports the finding of presence of very thin facial bone over the maxillary anteriors and frequent presence of fenestrations and dehiscence. Maxillary anteriors were seen in close proximity to the nasal cavity, therefore 3-dimensional pre-radiographic assessment using CBCT is important to assess the anatomical parameters which may hamper implant placement.
Acknowledgement
The project was supported by Deanship of Graduate Studies and Scientific Research at Dar Al Uloom University, Riyadh, KSA.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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