JICDRO is a UGC approved journal (Journal no. 63927)

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ORIGINAL ARTICLE
Year : 2010  |  Volume : 2  |  Issue : 1  |  Page : 4-10

Density evaluation of pre-implant sites by dentascan software


1 Department of Oral Medicine and Radiology, Dr. D. Y. Patil Dental College and Hospital, Pimpri, Pune - 18, India
2 Department Oral Medicine, Diagnosis and Radiology, MGV's KBH Dental College and Hospital, Nashik, Maharashtra, India
3 Department of Periodontology and Oral Implantology, Reader, Rangoonwala Dental College and Hospital, Pune, India

Date of Web Publication18-Nov-2011

Correspondence Address:
Prashant V Suvarna
303, Staffquarters, Dr. D. Y. Patil Dental College, Pimpri, Pune-18, Maharashtra
India
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Source of Support: Jupiter Heart Scan, Dadar, Mumbai, India, Conflict of Interest: None


DOI: 10.4103/2231-0754.89983

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   Abstract 

Objectives: To measure the bone density in Hounsfield unit (HU) values at the sites of implant placement by Dentascans, and correlate it with respect to sex, individual jaws, side of the jaw, and zone in the jaw. Study Design: Twenty-five patients in the age group of 10 and 80 years, requiring implant placement, were selected for this study, using Siemens Somatom Sensation 64. The density was evaluated subjectively by the Dentascan software. Density of the bone at the implant sites was correlated with the sex of the patients, individual jaw, and zone in the jaw. Moreover, an independent 't' test was applied and the 'P' value was determined at 95% confidence limits. Also the mean (minimum and maximum) density of the bone was evaluated according to the side of the jaw and an ANOVA test was applied followed by a Turkey test. Results: Based on the HU values, 75.40% values were in the D3 group, 16.39% in the D4 group, 4.95% in the D5 group, and 3.27% in the D2 group. In the D5 group, the lowest mean HU value was 124.5. Statistical analysis did not show any significant relationships. Conclusion: Bone density at the implant sites dictate the successful osseointegration of the implants. Dentascans provide a subjective evaluation of bone density at the implant sites.

Keywords: Dentascans, Bone density, Implants, Osseointegration


How to cite this article:
Suvarna PV, Jaju PP, Subramaniam AV, Jain S. Density evaluation of pre-implant sites by dentascan software. J Int Clin Dent Res Organ 2010;2:4-10

How to cite this URL:
Suvarna PV, Jaju PP, Subramaniam AV, Jain S. Density evaluation of pre-implant sites by dentascan software. J Int Clin Dent Res Organ [serial online] 2010 [cited 2019 Jul 23];2:4-10. Available from: http://www.jicdro.org/text.asp?2010/2/1/4/89983


   Introduction Top


Dental implants have attained immense popularity and wide acceptance because they are the conservative method of replacing lost teeth, and restore function with proprioception, aesthetics, and thereby revamp the self-esteem of the patients. Dental implant restorations have the highest survival rate compared to any other type of prosthesis to replace missing teeth. They do not decay nor do they require endodontic treatment. They are also less prone to fracture and resist periodontal-like disease better than teeth. Before attempting to treat a patient with a dental implant, dentists must determine the internal anatomy, the proximity to vital anatomic structures, soft tissue morphology, and bone quality. [1] Imaging information will allow optimum placement of the implants and enhance both short- and long-term success in all stages of the procedure. Density of the available bone in an edentulous site is a determining factor in treatment planning, implant design, surgical approach, healing time, and initial progressive bone loading during prosthetic reconstruction. [1] Periapical or panoramic radiographs are unhelpful when determining bone density because the lateral cortical plates often obscure trabecular pattern. In addition, the more subtle changes in bone density cannot be quantified using these radiographs. Computed tomography (CT) is currently the only diagnostically justifiable imaging technique that allows at least a rough conclusion about the structure and density of the jaw bones. The use of CT scans in conjunction with a special reformatting software, Dentascan, readily meets the pre-prosthetic imaging objectives, that is, identifying the disease, determining the bone quality, quantity, implant position, and implant orientation, and it surpasses the shortcomings of the conventional radiographic technique with detailed accuracy and reliability. [1] Dentascan is a dedicated post-scanning image evaluation software for the teeth and jaws, which creates panoramic and paraxial views of the upper and lower jaws.

The study has been undertaken to evaluate the density of the jaw bone at the pre-evaluation implant site, using Dentascan. Bone density can be evaluated using Hounsfield units (HU), which are directly related to tissue attenuation coefficients. Techniques such as histomorphometry of bone biopsies or densitometry, quantitative ultrasound, dual photon absorptiometry, quantitative computed tomography, although reliable, and quantitative measures of bone density, are not routinely feasible for the practice of implant dentistry.


   Materials and Methods Top


The basic objective of the study was to measure the bone density HU values at the sites of implant placement, using Dentascans.

The objectives of the study were as follows:

  1. Density of the bone at the implant sites to be correlated with the sex of the patients
  2. Density of the bone at the implant sites to be correlated with the individual jaw
  3. Density of the bone at the implant sites to be correlated with the zone in the jaw
  4. Density of the bone at the implant sites to be correlated with the side of the jaw


The selection of the patients was done at random, irrespective of sex, race, religion or socioeconomic status. The age group of the patients was between 10 and 80 years. Twenty-five patients were included for this study, with 61 implant sites. Patients reporting to the Outpatient Department of the college were clinically examined, by taking a detailed history to arrive at the clinical diagnosis.

Measurement of bone density

The CT scan machine used for this study was the Siemens Somatom Sensation 64. This had modified discrete cosine transform (MDCT) technology with a 32 detector array and 64 data channels. Sixty-four slices were obtained with effective mAs of 90, 120 kilovoltage, a pitch of 0.9, reconstruction increment of 0.5 mm, and image acquisition of 64 x 0.6 mm. The patient was subjected to a CT scan procedure and the images were obtained and reformatted into paraxial and panoramic images by Dentascans. The Dentascan software provided the means for assessing the subjective evaluation of available bone density at the implant site. This was done on the paraxial images obtained on the computer with help of the pixels tools present in the software. The most critical region of bone density is the crestal 7 to 10 mm of the bone. This determines the treatment protocol. [2]

To standardize the evaluation of density at the implant sites a circle was formed at a height of 7 mm from the crest touching both the inner buccal and the palatal / lingual cortical plates. [2] [Figure 1].
Figure 1: Measurement of the density at implant site

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After the formation of the circle, a circle histogram was plotted with the help of the software, which demonstrated the minimum and maximum values. Along with it a standard deviation was also given. Therefore, the minimum and maximum values were recorded. They were divided into five subdivisions based on the HU value.

Bone density based on HU values given by Misch: [ 1]

D1: > 1250 HU

D2: 850 - 1250 HU

D3: 350 - 850 HU

D4: 150 - 350 HU

D5: < 150 HU

Statistical analysis

Statistical analysis and computation procedures were performed. The collected data was entered into a MS-Excel worksheet and the use of the statistical package for social sciences (SPSS) software was completed and the results represented in the form of tables and graphs. The mean (minimum and maximum) density of the bone at the implant sites was correlated with the sex of the patients, individual jaw, and zone in the jaw, and an independent 't' test was applied and the 'P' value was determined at 95% confidence limits. Also the mean (minimum and maximum) density of the bone was evaluated according to the side of the jaw and an ANOVA test was applied followed by the Turkey test.


   Results Top


Bone density values in Hounsfield units at the implant sites

Density at the implant sites was assessed by utilizing the Hounsfield units (HU). It was divided into five groups based on the HU values

D1: > 1250 HU

D2: 850 - 1250 HU

D3: 350 - 850 HU

D4: 150 - 350 HU

D5: < 150 HU

There were a total of 61 implant sites that were assessed. No implant site belonged to the D1 category. The D2 category had two implant sites, with a maximum mean value of 1134 H.U.

D3 category had the maximum implant sites. A total of 46 implant sites were present in this category. In this category the HU value ranged from 350 HU to 850 HU. The highest value in this category was 799.5 HU, while the lowest value was 354 HU. The D4 category had a total of 10 implant sites with the lowest value of 156 HU and highest value of 341.5 HU.

The D5 category had a total of three implant sites with the lowest value of 124.5 HU and highest value of 146.5 HU [Table 1].
Table 1: Bone density at the implant sites in Hounsfield values

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Density and the relation of sex of the patients

A total of 25 patients were present, in which 13 were males and 12 were females. The minimum and maximum density was calculated for both the groups using an independent 't' test at a 95% confidence limit. In females the minimum mean density was 6.8750 HU. In males the minimum mean density was - 48.3846 HU.

The 'P' value for minimum density was 0.439, which implied that there was no significant correlation between the minimum density in both sexes. In females the maximum mean density was 1063.37 HU. In males the maximum mean density was 975.6262. The 'P' value for this group was 0.449, which implied that there was no significant correlation between the maximum density in both the sexes [Table 2].
Table 2: Maximum and minimum bone density according to sex of the patient

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Relationship between the bone density at implant sites and jaws

A total of 30 implant sites were present in both the jaws. In every patient a single, that is, mean HU value was considered for each jaw. Hence, there were 18 mandibular implant sites and 12 maxillary implant sites. The minimum and maximum mean densities were calculated for both jaws using the independent 't' test at 95% confidence limit. For mandibular implant sites, the mean minimum density was - 38.4444 HU. For the maxillary implant sites the mean minimum density was - 4.6042 HU. The 'P' value was 0.583, showing that the there was no correlation between the minimum bone density and jaws.

For the mandibular implant sites, the mean maximum density value was 1030.0306 HU. For the maxillary implant sites the mean maximum density was 976.5742 HU and the 'P' value was 0.610, which showed that there was no significant correlation between the maximum bone density and jaws [Table 3].
Table 3: Maximum and minimum mean bone density relating to the jaw

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Bone density correlation with the zone of implant placement in the jaws

In this a total of 30 implant sites were present. Seven implant sites were in the anterior region of the jaw and 23 implant sites were in the posterior region of the jaw. The minimum and maximum bone densities were calculated using the independent 't' test. In the anterior region, the mean minimum density was - 4.5357 HU. In the posterior region of the jaw the mean minimum density was - 31.1087 HU. The 'P' value was 0.710, which revealed no significant correlation between the anterior region of jaws and the minimum bone density. In the posterior region, the mean maximum density was 1018.887 HU. The 'P' value was 0.718, demonstrating that there was no significant correlation between the posterior region of jaw and the maximum bone density [Table 4].
Table 4: Bone density at implant sites according to zone in the jaw

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Relationship between the side of the jaw for implant placement and bone density

A total of 30 implant sites were present. It was divided into three groups. The right side of the jaw had 11 implant sites, the left side had seven implant sites, and the implant sides were present on both the right and left sides in a particular patient. The ANOVA test was applied at a 95% confidence limit followed by a Turkey test, to check intergroup variability. On the left side, the minimum mean bone density was - 48.5714 HU. On the right side, the minimum mean bone density was - 54.0155 HU. On both sides, the minimum mean bone density was 15.5767 HU and 'P' value was 0.549, showing that there was no significant correlation between the side of the implant placement and the minimum bone density. On the left side, the maximum mean bone density was 1006.1429 HU. On the right side the maximum mean bone density was 1048.6491 HU. On both sides, the maximum mean bone density was 973.4417 HU. The 'P' value was 0.817. This showed that there was no significant correlation between the maximum bone density and side of the jaw [Table 5].
Table 5: Minimum and maximum bone density according to the side of the jaw

Click here to view



   Discussion Top


This study was undertaken to evaluate the density at the implant sites, using Dentascan. The Dentascan software automatically displays multiple reconstructed cross-sectional and panoramic images of the jaw. The density of the available bone in an edentulous site is a determining factor in treatment planning, implant design, surgical approach, healing time, and initial progressive bone loading, during prosthetic reconstruction. The literature suggests that the anterior mandible has greater bone density than the anterior maxilla. The posterior mandible has poorer bone density than the anterior mandible. The poorest bone quality in the oral environment typically exists in the posterior maxilla and it is associated with dramatic failure rates. CT is currently the only diagnostically justifiable imaging technique that provides information about the density of the bone. Bone density can be evaluated using Hounsfield units (HU), which are directly related to tissue attenuation coefficients. The Hounsfield scale is based on density values for air, water, and dense bone, which are arbitrarily assigned values of -1000, 0, and + 1000, respectively. The most critical region of bone density is the crestal 7 to 10 mm of bone, and hence, it has been selected, to evaluate the density of the bone.

In the present study, the bone densities were measured on paraxial images and they were divided into five categories based on the HU values; 75.40% of the values were in the D3 group, 16.39% in the D4 group, 4.95% in the D5 group, and 3.27% in the D2 group. In the D5 group, the lowest mean HU value was 124.5. The remaining two cases in D5 were completely edentulous. The highest mean HU value was 1134. The highest mean HU value in the anterior maxilla was 727.5, while in the anterior mandible it was 1134. Similarly, the highest mean HU value in the posterior maxilla was 781 and in the posterior mandible it was 764.5. The HU value in this study ranged from - 233 to 2146. It was possible that higher HU values were reported because of a slight inclusion of cortical plates. The statistical analysis did not show any significant relationships between HU values and demographic data like gender, jaw, side, and zone in the arch. These findings were consistent with a similar study done by Shapurian et al. [3] However, in their study, a significant difference of P < 0.001 was observed in the anterior and posterior values. Previous studies using different approaches have shown discrepancies linked to hormonal factors and masticatory muscle strength. Kribb et al. failed to show an age-related difference in mandibular bone mineral density between normal and osteoporotic women. [4] Only a single study conducted by Shapurian et al. evaluated the bone density using the Hounsfield scale in relation to age and gender. [3] The density decrease in the jaws is related to the length of time the region has been edentulous and not loaded appropriately. Dentascans provide the clinician with Hounsfield values, a subjective method of evaluating bone density for a proposed implant site. Haldun et al. advocated the use of CT for determining bone quality and quantity. [5] Absolute guidelines on these HU values cannot be provided, as the density observations will be scanner-dependent and will vary according to the particular exposure settings and window levels applied. It is obvious that the HU variation observed in the same jaw scan reflects the local bone density variations, with lower HU values for poor bone quality. [6] Variability in values can alert the surgeon to modify the treatment plan so that primary stability in the bone of less density is ensured, and a longer healing period can then be planned. [3],[7] Dentascan provides an economical and feasible option to measure the density at implant sites, as opposed to the expensive and unfeasible density evaluation like histomorphometry of bone biopsies or densitometry, quantitative ultrasound or dual photon absorptiometry.


   Conclusion Top


Bone density at the implant sites dictates the successful osseointegration of the implants. Dentascans provide a subjective evaluation of the bone density at the implant sites. This study demonstrates that there is no significant correlation between bone density and age, sex, jaw, zone of the arch or side of the arch. This study advocates the use of the Dentascan, to measure the bone density at the implant sites, as a feasible and economical method.


   Acknowledgments Top


Jupiter Heart Scan, Dadar, Mumbai, India, Financial support: The authors have not received any financial support from any person nor any institution. The authors have funded this study by themselves.

 
   References Top

1.Louis TK, Carl EM. Diagnostic imaging and techniques, Contemporary Implant Dentistry. In: Carl EM, editors. 2 nd ed. Mosby; 1999. p. 73-87.  Back to cited text no. 1
    
2.Carl EM: Bone density: A key determinant for clinical success. In Contemporary implant dentistry. Dental Implant, 2 nd ed. Mosby; 1999. p. 109-18.  Back to cited text no. 2
    
3.Shapurian T, Damoulis PD, Reiser GM, Griffin TJ, Rand WM. Quantitative evaluation of bone density using the Hounsfield index. Int J Oral Maxillofac Implants 2006;21:290-7.  Back to cited text no. 3
    
4.Kribbs PJ. Comparison of mandibular bone in normal and osteoporotic women. J Prosthet Dent 1990;63:218-22.  Back to cited text no. 4
    
5.Iplikçioðlu H, Akça K, Cehreli MC. The use of computerized tomography for diagnosis and treatment planning in implant dentistry. J Oral Implant 2002;28:29-36.  Back to cited text no. 5
    
6.Jacobs R. Preoperative radiologic planning of implant surgery in compromised patients. Periodontol 2000 2003;33:12-25.  Back to cited text no. 6
    
7.Turkyilmaz I, Tözüm TF, Tumer C. Bone density assessments of oral implant sites using computerized tomography. J Oral Rehabil 2007;34:267-72.  Back to cited text no. 7
    


    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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