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Article

Optimal Buccal Site for Mini-Implant Placement on Attached Gingiva of Posterior Maxilla: A CBCT Study

by
Georgios Vasoglou
1,
Konstantinos Apostolopoulos
2 and
Michail Vasoglou
3,*
1
Private Orthodontic Practice, 17676 Athens, Greece
2
Orthodontics Department, School of Dental Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
3
Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
*
Author to whom correspondence should be addressed.
Appl. Sci. 2023, 13(12), 7099; https://0-doi-org.brum.beds.ac.uk/10.3390/app13127099
Submission received: 8 May 2023 / Revised: 6 June 2023 / Accepted: 12 June 2023 / Published: 14 June 2023
(This article belongs to the Special Issue Development and Applications of Digital Dentistry)
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Abstract

:
This research aims to investigate the optimal buccal site on the attached gingiva of the posterior maxilla for mini-implant placement for anchorage purposes in orthodontics. In 23 female patients, mini-implants were implemented between the roots of the first molar and second premolar, in the maxilla, for anchorage purposes. A CBCT was acquired for diagnostic purposes, and intraoral scanning was performed. Using the digital model that was the result of combining the DICOM and STL files, the cortical bone thickness and density, as well as the trabecular bone density, were measured on three axial bone slices corresponding to the three defined height levels (lower, middle, upper) on the attached gingiva, in the interradicular area. Pearson and eta correlation tests were performed in order to investigate possible correlations between height in the attached gingiva, and the corresponding cortical bone thickness and density, as well as the corresponding trabecular bone density. The correlations regarding the height level in the attached gingiva were medium for the cortical bone thickness, and weak for the cortical bone density, while a strong correlation was found between the cortical bone thickness and density. The upper level of the attached gingiva, between the second premolar and the first molar in the maxilla, is the optimal site for mini-implant placement, as the cortical bone thickness and density are probably greater than in the lower and middle level.

1. Introduction

Mini-implants are used routinely for enhancing anchorage in orthodontic treatments [1,2,3,4]. Factors such as the cortical bone thickness, the diameter and length of the mini-implant, and the angle and point of insertion in the mucosa have been proved to be crucial to successful placement [5,6]. Primary stability is also important to the implant’s survival rate. It depends on the bone quality, implant design, and preparation of the implant site [7].
Primary stability is measured using resonance frequency analysis (RFA) through a transducer attached to an implant fixture. The result is displayed as an implant stability quotient (ISQ) value, on a scale that indicates the level of stability of dental implants [8,9,10,11]. It is also measured using Periotest values (PTV) or insertion torque measurement [12,13,14]. The cortical bone thickness has been found to be directly proportional to the success rate of the mini-implant [15], while Kravitz et al. [16] stated that two crucial factors for primary stability are bone quality and quantity, which also affect the long-term survival of the mini-implant. Pan et al. [17], in agreement with Roze’ J et al. [18], stated that the primary stability of mini-implants depends on the cortical bone thickness in conjunction with the trabecular bone density, and concluded that the primary stability of a mini-implant can be estimated by computed tomography measurements of the cortical bone thickness and trabecular bone density, before treatment.
Cone beam computed tomography (CBCT) was introduced in 1998 [19], and is now widely used in dentistry for diagnosis and treatment planning, especially for dental implants and surgical cases [20]. In orthodontics, it is used in cases of impacted teeth [21], but clinicians recommend its use even in the field of temporomandibular joint (TMJ) problems, cleft lip and palate (CL/P), supernumerary teeth, or mini-implant placement. However, according to the “as low as reasonably achievable” radiography principle, we should limit the use of CBCT to only absolutely necessary occasions and, when we do so, CBCT should be performed using the smallest possible field of view (FOV) [22].
Among the above-mentioned factors that affect the primary stability of temporary anchorage devices, cortical bone thickness is believed to be the most important one, as these devices are not osseointegrated, but are mechanically retained in the bone [15]. Computed tomography (CT) [23] and CBCT [24] are both suitable for the assessment of cortical bone thickness. Measurements are usually conducted at several interradicular areas, and at several height levels. The cementoenamel junction (CEJ) and alveolar crest are the two usual reference planes that are used.
Cortical bone thickness was measured by Baumgaertel and Hans [25] in buccal segments and interdental areas from the second molar on the right side, to the second molar on the left, for the upper and lower jaw at 2, 4, and 6 mm from the alveolar crest, on dry skulls, utilizing CBCT imaging. The same reference plane was used by Ono et al. [26], who measured the thickness at 1 mm to 15 mm distance from the plane, in 1 mm intervals, in a CT study, while the alveolar process bone thickness was assessed by Yang et al. [27] at 1.5, 3, 6, and 9 mm from the CEJ plane, on axial slices, using the CBCT data of 50 adults. The cementoenamel junction was also used as a reference in the research of Fayed et al. [28], who measured the cortical bone thickness at 2 mm, 4 mm, and 6 mm from the CEJ, in a CBCT study of 100 patients divided into two age groups (adolescents and adults).
Bone density has been measured in several studies utilizing computed tomography (CT) [29,30] or CBCT [31,32,33,34,35] in Hounsfield units (HU). The assessment of bone density at sites where implants are scheduled to be placed is helpful in selecting the exact point for insertion or surgical methodology. A bone classification scale was proposed by Misch [36], depending on objective bone density measurements on CT. CBCT has replaced multi-slice CT (MSCT) due to the lower radiation, shorter acquisition time, higher resolution, and lower cost. When CT scans are used, the Hounsfield unit reflects the degree of X-ray attenuation assigned to each pixel and, in this way, the tissue density is expressed. When CBCT is used, it is the gray scale (voxel value) that indicates the degree of X-ray attenuation of each tissue. So, HU expresses the density of body tissues when compared to a calibrated gray-level scale.
Now, it is accepted that it is better for mini-implants to be placed at the attached gingiva [37]. The width of the attached gingiva is measured from the sulcus of each tooth, as it extends to the surface of the gums, to the mucogingival junction [38]. The mucogingival junction is a well-determined line between the movable and immovable mucosa [39]. The methods that are used to spot the mucogingival junction are the visual method (VM: identifying the line by the difference in color between the gingiva and alveolar mucosa), the VM after histochemical staining (HM), and the functional method (FM), which consists of distinguishing the borderline between stable and immovable tissues with a light pressure, delivered by a periodontal probe) [40,41]. So, the attached gingiva is easy to record, and it might be a guide when placing mini-implants, and seeking a satisfying primary stability.
For the buccal segments of the upper jaw, the interradicular space between the second premolar and first molar is an indicated region for mini-implant placement as, in this region, an adequate mesiodistal buccal/palatal distance is recorded [28]. Of course, the roots and the supporting periodontal ligament are notable limitations. As to height, however, in order for the best primary stability to be achieved, the cortical and trabecular bone quantity and quality should be defined, and this would be easy if each patient were subjected to a CBCT. As indicated above, acquiring a CBCT for that reason only is not appropriate. However, if a correlation exists between the height in the attached gingiva region, and the underlying bone thickness and density, this would favor the selection of the most suitable point for insertion.
This study aims to investigate a possible correlation between the height in the attached gingiva, and the underlying bone thickness and density, between the second premolar and first molar in the maxilla, as this would help in the selection of the most favorable point for insertion in terms of primary stability. The null hypothesis is that there is no significant correlation between the different heights in the attached gingiva, and the corresponding bone thickness and density.

2. Materials and Methods

The study sample consisted of 23 female patients, with a mean age of 24.3 years. Mini-implants were scheduled to be placed in the maxilla between the first molar and second premolar to facilitate anchorage purposes (in most cases, the right and left maxillary buccal region), and 43 sites were evaluated. The inclusion criteria were: periodontically healthy patients, with a CBCT imaging of the upper jaw, which was acquired for diagnostic and safety purposes (mainly impacted teeth were involved, or questionable tooth movements). Patients who presented poor oral hygiene, periodontal pathology, metabolic disease (diabetes), or deciduous teeth, or who smoked, were excluded from the study. The patients (or their representatives) were informed of the aim and procedures of the study, and they signed a consent form regarding the need for mini-implants, and the reasons for acquiring a three-dimensional X-ray (CBCT). This research is part of a protocol that was validated by the Ethics and Scientific Committee of 401 General Army Hospital in Athens, Greece (ref: No. 10/8-12-2020).
Prior to the mini-implant placement, CBCT imaging of the upper jaw was acquired (Planmeca ProMax® CBCT system, Planmeca Oy, Helsinki, Finland, 90 kVp/4–10 mA, 200–400 μm voxel size). The width of the attached gingiva in the maxillary arch, between the first molar and second premolar, was measured during the clinical examination of the patient, with the help of a periodontal probe (Figure 1a), utilizing the visual method, and study casts were constructed. The clinical procedure was applied to the patient’s cast, and the attached gingiva was marked by two lines. The first represented the mucogingival junction, and the wavy second one, the upper (apical) border of the free gingiva. A third straight line, connecting the upper borders of the second wavy line, was drawn, and so was a fourth line, in the middle of the first and third lines (Figure 1b). All the lines were engraved into the plaster model. All the plaster models were scanned with Carestream 3600 digital oral scanner (Carestream Dental, LLC, Atlanta, GA, USA), and a stereolithography (STL) file was acquired (Figure 1c).
Digital Imaging and Communications in Medicine (DICOM) files from the CBCT imaging and STL files were combined, using several matching points, to build a digital model on an open-source software (Blue Sky Plan V4.9.4 64 bit, Libertyville, IL, USA). On that digital model, the teeth, the supporting bone, and the mucosa could be evaluated at the same time. In the program panel, five interacting perspectives of the digital model could be inspected at the same time: 3D, panoramic, cross-sectional, axial, and implant/tangential (Figure 2).
The orientation of the digital model was set so that the palatal plane would be parallel to the horizontal axis, and the nasal septum would be parallel to the vertical axis, provided by the software, accordingly to the method of Fayed et al. [28]. The region for bone evaluation was on the midline between the first molar and second premolar on the right and left side of the upper jaw, where the mini-implants were scheduled to be placed. This region of interest was spotted on the panoramic and axial panel of the program. On the 3D panel, three axial slices were defined on the digital model, representing the first, third, and fourth engraved lines on the casts. The cortical bone thickness and density, and trabecular bone density were measured at the three defined levels on the corresponding coronal slice and panel, at the midline between the first molar and second premolar (Figure 3). The cortical bone thickness was measured as a distance perpendicular to the bone surface, utilizing the distance measuring tool, while the cortical and trabecular bone density were automatically calculated in Hounsfield units (HU), with the density measuring tool of the software (Βlue Sky Plan), on the same slices.
The trabecular bone density was measured very close to the inner border of the cortical bone. This was chosen because mini-implants penetrate the trabecular bone at several depths, depending on their length and the thickness of the soft tissue and the cortical bone. Thus, trabecular bone density, in the area of contact with the cortical bone, might be important for the primary stability, as this area applies to all lengths of mini-implants.

Statistical Analysis

For all the statistical tests, the Statistical Package for the Social Sciences software was used (SPSS 25.0, IBM, Chicago, IL, USA). The normal distribution of each variable was verified using the Shapiro–Wilk normality test. The intraclass correlation coefficient (ICC) test was used to assess the intra-rater reliability. A sample size calculation [42] with α-value = 0.05, β-value = 0.80, and r = 0.6 returned a sample size of 19 subjects. However, for a correlation coefficient (r) value of 0.5, 29 patients would be needed, so the results of this study should be interpreted with caution, as 23 patients and a total of 43 sites were evaluated.
For the statistical analysis, we used the Pearson correlation coefficient to examine any possible correlation between the cortical bone thickness and density, as the data were normally distributed, and eta correlation to examine any possible correlation among the gingival height and the cortical bone thickness, the cortical bone density, and the trabecular bone density.

3. Results

All measurements were performed by one investigator. The intra-observer reliability was assessed by ICC testing on 35% of the samples, with each variable being measured at two time points, and showed excellent reliability (0.995) between the measurements.
The cortical bone thickness and the cortical bone density were found to increase between the lower and the upper gingival height level, in both the right and left sides of the maxilla. Specifically, as is recorded by the mean values in Table 1, the cortical thickness increased from 0.71 mm at the lower level, to 0.98 mm at the middle, and 1.1 mm at the upper level on the right side, while on the left side, it increased from 0.67 mm, to 0.88 mm and 0.99 mm, respectively. The cortical bone density on the right side increased from 1155.75 HU at the lower level, to 1250.40 HU at the middle, and 1395.10 HU at the upper level, while on the left side, it increased from 995.85 HU, to 1171.20 HU and 1224.30 HU, respectively (mean values in Table 1).
However, the situation was different for the trabecular density. More specifically, the trabecular density was higher at the middle gingival level, on the right side (732.95 HU), and at the lower level (604.10 HU), on the left side (mean values in Table 1).
Regarding the correlation between the cortical bone thickness and cortical bone density, we found statistically significant correlation in both sides (p-value 0.018 for the right side and 0.001 for the left side). The thicker the cortical bone, the bigger the cortical bone density (Table 2).
Finally, we found a medium association between the gingival height and the cortical bone thickness, a weak association between the gingival height and the cortical bone density, and no association between the gingival height and the trabecular bone density, either for the right or the left side (Table 3).

4. Discussion

In the literature, several patterns relating to the cortical bone thickness at the buccal site of the posterior maxilla have been described. Some researchers have concluded that moving apically, the cortical bone thickness decreases at a distance of 4 mm from the alveolar bone crest, and then increases again up to the 6 mm level [25], and the same pattern is indicated by Kim et al. [43], who found that the cortical bone is thickest closest to and farthest from the CEJ, and thinnest in the middle. On the other hand, according to Fayed et al. [28], the buccal cortical thickness of the maxilla increases from the CEJ to the 4 mm level, and then decreases again from the 4 mm level to the 6 mm level. However, the measurements in these studies are on a different plane basis, as the level of the bony crest in the interradicular space is located at a distance of about 1.5 mm apically from the CEJ of the adjacent teeth. In the current study, the borders of the attached gingiva were utilized as the reference for the measurement of the cortical bone thickness, as these are easy to identify in clinical practice. The use of either the CEJ, or the contour of the alveolar crest, in deciding at which height a mini-implant should be placed, might be difficult or even impossible without acquiring radiographic imaging. On the other hand, the limit between the free and attached gingiva is easy to clinically determine, and so is the mucogingival junction. The results of this study suggest that at the upper level of the attached gingiva region, the cortical bone is probably thicker than at the lower and middle levels. As the lower level that is utilized in the present study is about 1.5–2 mm above the alveolar crest level, this is in correspondence with the 2 mm level of Baumgaertel and Hans [25], while the upper level is in correspondence with the 6 mm level. Thus, the results of this study are in agreement with Baumgaertel and Hans [25]. In the study conducted by Fayed et al. [28], the CEJ was utilized as the reference, and measurements were made at 2, 4 and 6 mm cuts in the CBCT images. They reached the conclusion that the buccal cortical thickness in the posterior maxilla increased as the level cuts moved in an apical direction from the CEJ to the 4 mm level, and then they decreased again at the 6 mm level. They utilized the 6 mm level as the maximum level of measurement, as such a distance from the CEJ is probably inside the region of the attached gingiva. However, since the upper level of the attached gingiva that was utilized in the present study, as the maximum level of measurements, might be beyond the 6 mm distance from the CEJ, this may be the reason for the disagreement as to the buccal cortical bone thickness at the posterior maxilla region.
The same software and methodology used in the present study were used in a study of cortical bone thickness measurements at the buccal and lingual sides of the upper and lower jaw by Al Hafidh et al. [44]. The results for the region mesial to the upper molars were found to range from 1.35 mm to 1.76 mm, while moving gradually to 2, 4, 6, 8 mm distance from the CEJ for males, and from 1.36 mm to 1.64 mm for females. In the literature, there is controversy regarding the impact of gender on cortical bone thickness measurements. In the study of Ozdemir et al. [45], no statistically significant difference was found in cortical bone thickness measurements between groups of different facial type regarding gender, and this is in agreement with Farnsworth et al. [46] as, in their study, no significant differences were recorded in cortical bone thickness between genders. However, Ono et al. [26] stated that in the upper jaw, on the attached gingiva mesial to the first molar, the cortical bone was thinner in females than in males. In the present study, only female patients were included, assuming that gender might affect the results, and the cortical bone thickness was recorded from 0.44 mm to 0.61 mm for the right side, and 0.67 mm to 0.99 mm for the left side, while moving from the lower to the upper height level.
The findings of this study are also in relevant agreement with Casseta et al. [47], who stated that the cortical bone thickness and density at the buccal side of the alveolar process demonstrate a significant linear increase from crest to base. In their study, the cortical bone thickness and density were measured at 2, 4, 6 and 8 mm distance apical to the alveolar crest in several interradicular sites, in groups that were organized on the basis of age, gender, side, and site. However, the results of the current study suggest that there is a weak association between the buccal cortical bone density and the height levels (lower, middle and upper) of the attached gingiva, and a medium association between the buccal cortical thickness and the same height levels of the attached gingiva in the upper jaw, in the interradicular area between the first molar and second premolar.
According to Misch categorization [36], in this study, the cortical bone density on the right-side upper height level of the attached gingiva (mean: 1395.10 HU), and on the same side middle height level (mean: 1250.40 HU), belongs to the D1 range (above 1250 HU). On the left-side upper height level (mean: 1224.30 HU) and middle height level (mean: 1171.20 HU), and on the right and left-side lower height level (mean: 1155.75 HU and 995.85 HU, respectively), the cortical density falls in the D2 range (between 850 and 1250 HU). The trabecular bone density is measured below 850 HU in all sites, and thus is categorized in the D3 range (350–850 HU).
In a similar methodological study, Morar et al. [48] measured the buccal and palatal/lingual internal cortical bone and trabecular bone density at a depth of 2 mm from the alveolar crest. They recorded higher bone density values for the anterior region in contrast to the posterior, for both the maxilla and mandible. The highest bone density value was measured in the anterior mandibular area, and the lowest bone density value was found in the posterior mandible region, followed by the density at the posterior maxillary region.
In the present study, we aimed to establish a relationship between the evaluation of cortical bone thickness from a CBCT and from clinical land-marks, in an attempt to not use CBCT imaging for this purpose. This was also attempted by a recent study [49], in which the buccal alveolar bone thickness was evaluated in CBCT and in corresponding digital models, and a strong correlation between them was identified. In the latter study, buccal cortical bone thickness was also measured at 2, 4 and 6 mm distance from the alveolar ridge in the CBCT image, and was found to range from 1.06 to 1.73 mm, while no significant differences between 2, 4, and 6 mm were recorded, which is in disagreement with the presented study. On the contrary, Tepedino et al. [50], in a meta-analysis study, reported on “safe-zones” for mini-implant insertion, regarding cortical bone thickness. They concluded that in the posterior maxilla, the safest site is mesial to the first molar, at 6 mm from the cementoenamel junction.
In the present study, the cortical bone thickness was evaluated at the middle of the interradicular space between the first molar and second premolar at three height levels of the attached gingiva, but in a study by Holmes et al. [51], in which the cortical bone was evaluated at 4 and 6 mm from the alveolar crest, it was found to be thicker adjacent to roots, than at the midpoint between two adjacent teeth, while the 6 mm level measurement was not significantly higher than the 4 mm level.
Utilizing CBCT imaging for measuring bone density is not believed to be reliable by some researchers, because of the influence of parameters such as the device or the positioning of the patient [52]. Other studies [53] have declared that CBCT should not be the examination of choice for the characterization of bone quality on the basis of values compared with predetermined standards and, instead, values for symmetrically positioned areas, inside the field of view (FOV), could be used. On the other hand, there are studies that consider CBCT useful for measuring bone density, and thus provide clinicians with a density scale for the safe placement of implants [54].
In this study, bone density was assessed in CBCT images, using HU, for the buccal cortical bone corresponding to the three studied levels in the attached gingiva (lower, middle, upper), and for the trabecular bone, very close to the inner border of the cortex, at the three studied levels, as well.
In the study conducted by Pan et al. [17], it was found that at the buccal region in the maxilla, and distal to the second molar (mean value 1.3 mm), the cortical bone thickness was significantly lower than that in the mesial and distal region of the first molar (mean values 1.8 mm and 1.5 mm, respectively). It was also found that as the trabecular bone density decreased, the values of resonance frequency (RF) analysis (utilized as the measure of the primary stability of the mini-implants) also decreased. In the present study, a correlation between the trabecular bone density very close to the buccal cortex, and the vertical levels of the attached gingiva, was not established.
As to the possible correlation between the cortical bone thickness and density, it was found in the present study that there is a positive correlation between them (Table 2). This finding is not in agreement with the study conducted by Al Hafidh et al. [55], who found a significant negative correlation between the cortical bone thickness and cortical bone density at certain surfaces of the maxilla (distal of the first and second premolars, at 6 mm from the CEJ). This finding was attributed to the deformation under the masticatory loading of the wide alveolar region at the posterior maxilla, and distribution of the stress. Instead, significant positive correlation was found between the cortical bone thickness and density in the palatal region of the anterior teeth, and in the buccal and lingual region of the mandibular premolars and molars, and this was attributed to the stress concentration in these areas, due to the masticatory function. As the authors of that study declared, the correlation between the cortical bone thickness and density should be taken into consideration when planning the site of insertion of mini-implants.
A limitation that the study presented was the small sample size and, as already stated, the results of this study should be interpreted with caution. On the other hand, only female patients were examined so as to avoid heterogeneity regarding the gender of the patients. As differences in the thickness of the cortical bone, and differences in the density of the cortical and trabecular bone, between different genders and ages, are recorded in the literature, studies with a better and bigger standardized sample are needed.

5. Conclusions

The cortical bone thickness at the interradicular space between the second premolar and first molar in the buccal site of the upper jaw is positively correlated with the height level of the attached gingiva and the corresponding cortical bone density, in females. So, for this study population, the upper level of the attached gingiva in this region is most suitable in terms of primary stability for mini-implant placement.

Author Contributions

Conceptualization, M.V.; methodology, M.V.; validation, M.V. and G.V.; investigation, G.V. and M.V.; writing—original draft preparation, G.V., K.A. and M.V.; statistics, K.A.; writing—review and editing, G.V., K.A. and M.V.; supervision, M.V. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki, and was part of a study protocol approved by the Scientific and Ethics Committee of 401 General Army Hospital in Athens, Greece (ref: No. 10/8-12-2020).

Informed Consent Statement

Written consent to publish this paper has been obtained from the patients of the cases presented.

Data Availability Statement

Data are available upon reasonable request.

Conflicts of Interest

The authors declare no conflict of interest.

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Applsci 13 07099 g001 550
Figure 1. Measurement of the attached gingiva with (a) periodontal probe. (b) The four lines in the attached gingiva, engraved into the plaster model. (c) The STL file of the plaster model.
Figure 1. Measurement of the attached gingiva with (a) periodontal probe. (b) The four lines in the attached gingiva, engraved into the plaster model. (c) The STL file of the plaster model.
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Figure 2. The program panel, with the five interacting windows where the region of interest for measurements is defined.
Figure 2. The program panel, with the five interacting windows where the region of interest for measurements is defined.
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Figure 3. (a) The region (rectangular shape) in which measurements were performed at the lower, middle, and upper level of the attached gingiva. (b) The measurements on the selected coronal slice of the CBCT image, at the middle height level of the attached gingiva, indicated by the blue line, which is in correspondence with the blue line on the left photograph. The same measurements were performed for the lower and upper height levels.
Figure 3. (a) The region (rectangular shape) in which measurements were performed at the lower, middle, and upper level of the attached gingiva. (b) The measurements on the selected coronal slice of the CBCT image, at the middle height level of the attached gingiva, indicated by the blue line, which is in correspondence with the blue line on the left photograph. The same measurements were performed for the lower and upper height levels.
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Table
Table 1. Descriptive statistics.
Table 1. Descriptive statistics.
Right SideLeft Side
Gingival HeightMinMaxMeanSDMinMaxMeanSD
Cortical thickness (mm)Lower0.441.070.710.190.380.950.670.15
Middle0.531.340.980.260.511.260.880.23
Upper0.611.631.10.320.541.430.990.23
Cortical density (HU)Lower58618771155.75386.726181550995.85238.05
Middle56718961250.40372.5273718531171.20260.55
Upper69220441395.10414.8082122341224.30342.37
Trabecular density (HU)Lower1521364615.25357.171601576604.10299.69
Middle2851636732.95174.29611195510.95300.92
Upper411779689.35420.12441299590.25372.49
Table
Table 2. Pearson correlation between the cortical bone thickness and cortical bone density.
Table 2. Pearson correlation between the cortical bone thickness and cortical bone density.
Cortical Bone Density
Right Side/p-ValueLeft Side/p-Value
Cortical bone thickness0.0180.001
Table
Table 3. Eta correlations among the gingival height and cortical bone thickness and density, and the trabecular bone density.
Table 3. Eta correlations among the gingival height and cortical bone thickness and density, and the trabecular bone density.
Gingival Height
Right SideLeft Side
Eta ValueAssociationEta ValueAssociation
Cortical bone thickness0.490medium0.526medium
Cortical bone density0.251weak0.353weak
Trabecular bone density0.129no0.136no
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Vasoglou, G.; Apostolopoulos, K.; Vasoglou, M. Optimal Buccal Site for Mini-Implant Placement on Attached Gingiva of Posterior Maxilla: A CBCT Study. Appl. Sci. 2023, 13, 7099. https://0-doi-org.brum.beds.ac.uk/10.3390/app13127099

AMA Style

Vasoglou G, Apostolopoulos K, Vasoglou M. Optimal Buccal Site for Mini-Implant Placement on Attached Gingiva of Posterior Maxilla: A CBCT Study. Applied Sciences. 2023; 13(12):7099. https://0-doi-org.brum.beds.ac.uk/10.3390/app13127099

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Vasoglou, Georgios, Konstantinos Apostolopoulos, and Michail Vasoglou. 2023. "Optimal Buccal Site for Mini-Implant Placement on Attached Gingiva of Posterior Maxilla: A CBCT Study" Applied Sciences 13, no. 12: 7099. https://0-doi-org.brum.beds.ac.uk/10.3390/app13127099

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