The authors have declared that no competing interests exist.
The present study was undertaken to do a comparative evaluation of the role of Cone Beam Computed Tomography (CBCT) imaging and Orthopantomography (OPG) for pre-operative implant planning in combination with sinus grafting procedures in order to assess sinus anatomy and morphology and the existing bone height in three dimensions.
To assess sinus anatomy and morphology and the existing bone height in three dimensions.
Pre-operative assessment of maxillary sinuses for implant planning using CBCT imaging was performed on 20 sinuses (17 patients). These patients were subjected to orthopantomographs and CBCT imaging both pre-operatively and post-operatively. CBCT imaging helped to decide the type of sinus augmentation procedure best suited for the patients as per the individual needs and depending on the residual alveolar bone height, timing of implant placement, sinus morphology, anticipation of complication and comparative analysis between pre-and post-procedural gain in vertical alveolar bone height and increase in bone density.
The results were tabulated and statistically analyzed using Paired and Unpaired t-tests.
In the majority of cases, there was a concordance between the treatment type based on pre-operative and post-operative CBCT scans. The assessment of sinus morphology revealed a significantly higher detection rate of abberations in the form of sinus mucosal hypertrophy and septae on CBCT which were imperceptible on routine radiographs. The most appealing result was that vertical alveolar bone height could be measured precisely and there was a significant increase in surgical confidence and a significantly better prediction of complications when using CBCT imaging.
A pre-operative planning based on CBCT imaging seems to improve sinus diagnostics and helps to execute a better treatment plan. Also, it is a good tool for the comparison of vertical alveolar bone height pre-and post-operatively following sinus augmentation procedures using various graft materials.
Apart from clinical evaluation, diagnostic imaging is an integral part of dental implant therapy for pre-operative planning and peri-and post-operative evaluations by use of various imaging techniques. Intra-oral radiography, although easily available and relatively inexpensive, is not considered satisfactory in giving reliable information regarding the anatomy of the region due to its major constraints of overlapping and superimpositions and geometric and anatomic limitations in the form of the measurements, for the teeth and surrounding bone and other anatomic landmarks, which change with a change in the angulations used during the exposure of the radiographs. Moreso, their being with, considerate overlapping and superimpositions, which is an inherent and practically impossible disadvantage to exclude, make them a little less reliable for planning implant therapy. For instance, extraoral radiography can be used and proven helpful in certain conditions in dentistry. With regard to orthopantomography, lack of image sharpness and resolution, apart from unequal magnification and geometric distortion, which are the major constraints in panoramic radiography, the other name for orthopantomography, often lead to an inaccurate interpretation and measurements.
however, there is a dearth of studies regarding the comparison between CBCT and panoramic radiography for planning sinus augmentation procedures prior to implant placement in the literature. The present study was undertaken to do a comparative evaluation of the role of Cone Beam Computed Tomography (CBCT) imaging and Orthopantomography (OPG) for pre-operative implant planning in combination with sinus grafting procedures in order to assess sinus anatomy and morphology and the existing bone height in three dimensions.
Sinus augmentation procedures were carried-out in 17 patients seeking implant options for oral rehabilitation including 10 for direct and 10 of indirect procedures (n=20, 10 direct and 10 indirect). The study comprised of 43% females and 57% males with a mean age of 46.07 years. A total of 17 patients (20 segments) satisfying the above criteria requiring placement of implants in atrophic maxilla/ increased pneumatisation of the maxillary sinus were selected for the study. The patients were informed about the study including the use of the synthetic graft material and their approval was sought before their inclusion in the study. A written informed consent was obtained from each of the participating patients. For each patient, a detailed case history was taken including chief complaint, history of presenting illness and medical history and personal history. A thorough clinical examination, including systemic and regional examination, was done. Patients with sinus pathology, previous sinus surgeries, chronic smokers, patients under 18 years of age, and with underlying systemic conditions which contradicts any surgical procedures were excluded from the study. The type of sinus lift was decided based on the pre-operative residual bone height evaluated radiographically. The residual bone height was recorded using CBCT scan and a computer based software where the measurements were made from the crest of the ridge till the sinus floor lining. Indirect sinus augmentation was done in patients with a bone height of <9mm but more than or equal to 5mm. Patients with a bone height of less than 5mm were taken up for direct sinus augmentation. The period of edentulousness varied from 6 months to 12 months. Apically tapered, commercially pure titanium implants (Life Care Devices Private Limited Mahim, West Mumbai, India) were used for patients undergoing indirect sinus augmentation. The length of implant was 8, 10, and 11.5 with diameters of 3.5, 4.0, and 5 mm respectively. Patients in the category of direct augmentation underwent the lateral approach procedure and augmentation with an alloplastic graft material. Implant placement was done after 6 months as the second stage procedure. The patients were assessed clinically at immediate post-operatively, and at 1 week, 1 month, 3 months, and 6 months post-operatively. Radiographic assessment for bone height was done pre-operatively and at 6 months post-operatively using cone beam computer tomography. In this comparative study, the measurements were tabulated and statistically analyzed to evaluate the difference in increase in bone height between direct and indirect sinus augmentation procedures radiographically. Orthopantomographs (screening tool) were taken to rule-out other pathologies and as a part of initial assessment. CBCT scans were assessed for pre-operative and post-operative bone height, bone width and bone density. The CBCT scans were obtained from Kodak 9300 which is a hybrid machine using a CS3D imaging software and flap panel detector sensor with exposure parameters of 90 KVp and 10 mA and resolution of 90 microns. The cross sections were made 1mm apart. (
The results were tabulated and the statistical analysis was carried-out. The statistical tests used for the analysis of the results were: Paired t-test; and Unpaired t-test.
Cases done with pre-operative CBCT evaluations (only 4 representative cases are being discussed to avoid repetition):
With a pre-operative residual bone height of 0.8 mm in 16 region and 1.5 mm in 17 region, direct sinus augmentation was carried-out in a 40 year old male patient followed by implant placement of 3.75 x 11.5 dimensions as a single step procedure. Lateral window was created and synthetic graft material was dispensed through the lateral osteotomy site to maintain the elevated sinus membrane followed by placement of two dental implants through the crestal approach measuring 3.75 x 11.5 mm under local anesthesia and strict aseptic protocols. At the end of 6 months, a CBCT scan was advised to evaluate the increase in bone height which was 11 mm and 10.8 mm in 16 and 17 region respectively. (
A 45 year old patient with a residual bone height of 6.6 mm in 17 region underwent procedure of indirect sinus elevation using sinus osteotomy in relation to 17 region. Synthetic graft material was dispensed through the crestal osteotomy site to maintain the elevated sinus membrane followed by placement of a dental implant measuring 5 mm x 10 mm under local anesthesia and strict aseptic protocols. The implant was allowed to osseo-integrate for a period of six months during which the patient was followed periodically and was assessed for peri-implantitis, crestal bone loss and mobility. At the end of 6 months, a CBCT scan was advised to evaluate the increase in bone height which was 12mm. (
A 75 year old man reported to the unit seeking options for replacement of his missing upper right first molar with fixed prosthesis. Due to the residual bone height of 5.3 mm, the patient was advised and subsequently, underwent the procedure of indirect sinus elevation using sinus osteotomy in relation to 16 region followed by placement of a dental implant measuring 5 mm x 10 mm under local anesthesia and strict aseptic protocols. The implant was allowed to osseo-integrate for a period of six months during which the patient was followed periodically. At the end of 6 months, a CBCT scan showed an increase in bone height to 11.5 mm. (
A 19 year old young woman was referred to Department seeking options for rehabilitation of missing right upper first molar with fixed prosthesis as she was uncomfortable with the removable partial denture in relation to 16. The residual bone height in region was 4 mm in 16 tooth region. Patient was taken-up for direct sinus elevation via lateral window approach for sinus augmentation in relation to 16. Under aseptic conditions and local anesthesia, lateral wall of maxilla was exposed after muco-periosteal flap elevation. A window was created of 1cm diameter corresponding to apical aspect of 16. Sinus membrane was identified and elevated using sinus elevators and reamers without perforating the lining. Once the sinus membrane was elevated, graft material was dispensed to achieve an augmentation of 1cm assessed clinically and confirmed using post-operative OPG. At the end of 6 months, a CBCT scan showed an increased bone height of 12.7 mm. (
The present study involved evaluation of bone regeneration in terms of increase in residual bone height and bone density following sinus augmentation procedures. It included a total of 20 segments in 17 patients requiring sinus augmentation either by an indirect or a direct approach which was decided based on the residual alveolar bone height on CBCT scans. The study included 9 males and 8 females. The gender distribution in the indirect sinus augmentation procedures was 4 males and 6 females while direct sinus augmentation was done in 6 males and 3 females. 2 patients (one male and one female) underwent both direct and indirect sinus augmentation on their right and left maxillary quadrants and one female underwent direct technique on both sides. The region of sinus augmentation varied from premolar to molar region with the majority of it being in the 1st molar region. In indirect sinus augmentation procedure, as measured by CBCT, the average pre-operative height of bone was 6.8 mm while post-operative height of bone was 11.86 mm. A paired sample t-test was carried-out to know the difference in pre-and post-treatment measurements of bone height with indirect sinus augmentation procedure. The post-treatment bone height (11.86+1.11) was significantly higher than pre-treatment bone height (6.8 +0.70) (t=12.9, p<0.005) (
Indirect Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
Pre-Operative | 6.8 | 0.7 | 5.06 + 1.24 | 12.9 | <0.005 (Significant) |
Post-Operative | 11.86 | 1.11 |
In direct sinus augmentation procedure, the average pre-operative height of bone was 2.44 mm while post-operative height of bone was 11.27 mm. When a paired sample t-test was carried-out to know the difference in pre-and post-treatment measurements of bone height with direct sinus augmentation, it showed that the post-treatment bone height (11.27 +0.71) was significantly higher than pre-treatment bone height (2.44 +0.81) (t=32.17, p<0.005). (
Direct Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
Pre-Operative | 2.44 | 0.81 | 8.83 + 0.9 | 32.17 | <0.005 (Significant) |
Post-Operative | 11.27 | 0.71 |
In indirect sinus augmentation procedure, as measured by OPG, the average pre-operative height of bone was 7.2 mm while post-operative height of bone was 10.2 mm. A paired sample t-test was carried-out to know the difference in pre-and post-treatment measurements of bone height with indirect sinus augmentation procedure. The post-treatment bone height (10.2+0.92) was significantly higher than pre-treatment bone height (7.2 +1.23) (t=10.06, p<0.005) (
Indirect Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
Pre-Operative | 7.2 | 1.23 | 3.0+ 0.94 | 10.06 | <0.005 (Significant) |
Post-Operative | 10.2 | 0.92 |
In direct sinus augmentation procedure, the average pre-operative height of bone, as measured by OPG, was 1.3 mm while post-operative height of bone was 8.85 mm. When a paired sample t-test was carried-out to know the difference in pre-and post-treatment measurements of bone height with direct sinus augmentation, it showed that the post-treatment bone height (8.85 +1.0) was significantly higher than pre-treatment bone height (1.3 +0.92) (t=19.33, p<0.005). (
Direct Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
Pre-Operative | 1.3 | 0.92 | 7.55+ 1.23 | 19.33 | <0.005 (Significant) |
Post-Operative | 8.85 | 1 |
When a comparison was done in the assessment of mean pre-operative height of bone in the indirect sinus augmentation procedure as measured by CBCT and OPG, the average pre-operative height of bone was 6.8 + 0.70 in case of CBCT while 7.2 + 1.23 in case of OPG. When a paired sample t-test was carried-out to know the difference in pre-treatment measurements of bone height with indirect sinus augmentation in case of CBCT and OPG, it showed a p-value of 0.173, which was not significant. (
Pre-operative Bone Height (in mm) in Indirect Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
OPG | 7.2 | 1.23 | 0.4 + 0.86 | 1.48 | 0.173 (Not significant) |
CBCT | 6.8 | 0.7 |
When a comparison was done in the assessment of mean post-operative height of bone in the indirect sinus augmentation procedure as measured by CBCT and OPG, the average post-operative height of bone was 11.86 + 1.11 in case of CBCT while 10.2 + 0.92 in case of OPG. When a paired sample t-test was carried-out to know the difference in post-treatment measurements of bone height with indirect sinus augmentation in case of CBCT and OPG, it showed a p-value of <0.005, which was significant. (
Post-operative Bone Height (in mm) in Indirect Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
OPG | 10.2 | 0.92 | 1.66 +0.84 | 6.21 | <0.005 (Significant) |
CBCT | 11.86 | 1.11 |
When a comparison was done in the assessment of mean pre-operative height of bone in the direct sinus augmentation procedure as measured by CBCT and OPG, the average pre-operative height of bone was 2.44 + 0.81 in case of CBCT while 1.3 + 0.92 in case of OPG. When a paired sample t-test was carried-out to know the difference in pre-treatment measurements of bone height with indirect sinus augmentation in case of CBCT and OPG, it showed a p-value of <0.005, which was significant. (
Pre-operative Bone Height (in mm) in Direct Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | ||
Mean | Std. Deviation | t-value | p-value | ||
OPG | 1.3 | 0.92 | 1.14 + 0.35 | 10.39 | <0.005 (Significant) |
CBCT | 2.44 | 0.81 |
When a comparison was done in the assessment of mean post-operative height of bone in the direct sinus augmentation procedure as measured by CBCT and OPG, the average post-operative height of bone was 11.27 + 0.71 in case of CBCT while 8.85 + 1.0 in case of OPG. When a paired sample t-test was carried-out to know the difference in post-treatment measurements of bone height with indirect sinus augmentation in case of CBCT and OPG, it showed a p-value of <0.005, which was significant. (
Post-operative Bone Height (in mm) in Direct Sinus Augmentation | Bone Height (in mm) | Difference | Paired t-test | |||||||
Mean | Std. Deviation | t-value | p-value | |||||||
OPG | 8.85 | 1 | 2.42 +0.88 | 8.71 | <0.005 (Significant) | |||||
CBCT | 11.27 | 0.71 |
Radiology and imaging plays an important part in any minor or major surgical procedure which is planned. The pre-surgical radiographic assessment allows the surgeon to plan implant insertion in the sub-antral maxillary regions. An accurate pre-surgical planning, based on adequately selected radiology and imaging techniques, ensures optimal surgical results. By bringing new and detailed information through cross-sectional imaging and three dimensional assessment of the region in the pre-surgical phase of treatment, the present study revealed that cone beam computed tomography (CBCT) may change treatment planning for the various sinus lift procedures carried-out in cases with atrophic maxillae and in the presence of numerous other anatomic constraints. There have been a dearth of such studies with statistically significant results comparing the role of conventional radiography, most commonly used, orthopantomography or, panoramic imaging (OPG) and various modalities of cross-sectional imaging including CBCT, which proved the need for the study. Cross-sectional imaging is supposed to influence the treatment planning in such cases at probably all levels including the decision to perform such procedures, sinus anatomy, time of implant placement, the technique used for intervention and the volume of graft material to be used. Radiographic evaluation is necessary for information regarding the quantity and quality of the bone available and to localize anatomic structures in the proximity of the region where the procedure is supposed to be carried-out. Pre-surgical implant imaging should provide information about the implant site with regards to the osseous morphology such as knife edge ridges, cortical irregularities and thickness, developmental variations, enlarged marrow spaces, density of the trabecular bone and post-extraction irregularities in addition to the amount of bone available for implant placement alongwith the orientation of the alveolar bone. Lekholm and Zarb developed a grading scheme for the quality of bone in the proposed implant site in terms of relative proportion and densities of the cortical and medullary bones. According to this scheme, the bone of the alveolar process can be divided into 4 classes:
1.Almost the entire jawbone is composed of homogeneous compact bone;
2.A thick layer of compact bone surrounds a core of dense trabecular bone;
3.A thin layer of compact bone surrounds a core of dense trabecular bone of optimal/favorable strength;
4.A thin layer of compact bone surrounds a core of low density trabecular bone.
Cross-sectional imaging is required to apply this scheme for implant site assessment. Panoramic imaging has previously been used to study the grafted sinus floors and their relationship with dental implants. However, the position of the maxillary sinus floor was difficult to be assessed on two-dimensional imaging. As cone beam computed tomography (CBCT) has numerous advantages over conventional radiography as well as computed tomography (CT), we included CBCT for carrying-out the intended sinus augmentation procedures, this being in accordance with the study conducted by Temmerman
Based on the findings of the above study, it can be concluded that CBCT has an important role in cases of sinus lift procedures to improve the diagnostic efficiency as well as the accuracy of sinus lift procedures. In addition, it is extremely helpful in the pre-surgical planning of the sinus lift procedures and for an efficient comparison of the gain in vertical alveolar bone height post-graft placements. When only panoramic radiographs are used, bone quantity and quality are risked to be over-estimated. The present study demonstrates that CBCT increases the accuracy of both, the sinus morphology assessment as well as the estimation of gain in vertical alveolar bone height, in addition to bone density, which remains unassessed by conventional radiological techniques.