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ORIGINAL ARTICLE
Year : 2012  |  Volume : 4  |  Issue : 1  |  Page : 32-36

Prediction of further residual ridge resorption by a simple biochemical and radiographic evaluation: A pilot study


1 Department of Prosthodontics, M. A. Rangoonwala College of Dental Sciences and Research Centre, Pune, India
2 Department of Intern, M. A. Rangoonwala College of Dental Sciences and Research Centre, Pune, India

Date of Web Publication10-Sep-2012

Correspondence Address:
Jay D Matani
Department of Prosthodontics, M. A. Rangoonwala College of Dental Sciences and Research Centre, Pune
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-8844.99889

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  Abstract 

Background and Objective: The success of a removable denture is measured by its retention and stability which rely on the structural integrity exhibited by the underlying residual ridge. However the residual ridge undergoes a progressive resorption, causing a reduction in its size. The multifactorial etiology of the reduction of residual ridges makes it significant for the operator to try and understand as well as to predict the rate of resorption prior to fabrication of dentures. The objective of the study was to evaluate a simple, fast and cost effective diagnostic tool to study and anticipate ridge resorption. Materials and Methods: 17 completely edentulous male patients were selected for the study. Standardized orthopantomographs were made for all the subjects and measurements were made on them. The resorption index was calculated for each patient. A random urine sample was taken from each patient to investigate the 24 hours urinary calcium-creatnine ratio. Results: A direct relation was seen between patients with lower resorption index and lower 24 hours urinary calcium-creatnine ratio. Clinically these cases had undergone a marked amount of reduction in the residual alveolar ridges with respect to the width and height. Also, a direct relation was seen when the patients presented with higher 24 hours urinary calcium-creatnine ratio and greater resorption index. These patients presented with good height and width of the residual ridges. Conclusion: Our study shows a direct relation between the resorption of the bone and the calcium-creatinine levels of the edentulous subjects. The calcium-creatnine ratio in conjunction with the resorption index can be used as a simple and cost effective diagnostic tool.

Keywords: Mandible, oral bone loss, residual ridge resorption, urinary calcium, urinary creatinine


How to cite this article:
Kheur M, Matani JD, Latifi M. Prediction of further residual ridge resorption by a simple biochemical and radiographic evaluation: A pilot study. J Orofac Sci 2012;4:32-6

How to cite this URL:
Kheur M, Matani JD, Latifi M. Prediction of further residual ridge resorption by a simple biochemical and radiographic evaluation: A pilot study. J Orofac Sci [serial online] 2012 [cited 2020 Dec 1];4:32-6. Available from: https://www.jofs.in/text.asp?2012/4/1/32/99889


  Introduction Top


Caries, periodontal problems or trauma are the most frequent causes for the loss of a tooth. A completely edentulous patient generally has undergone a combination of the above factors. However, irrespective of the etiology of tooth loss, the alveolar bone undergoes a series of changes in the form of remodelling thus forming the residual ridge. [1] Residual ridge would be hence the term used to describe for the portion of the residual bone and its soft tissue covering that remains after the removal of teeth. [2] However the process of remodelling does not end here. The residual bone is capable of losing more tissue substance by either a physiological process or a pathological one. This is referred to as a progressive resorption of bone. Hence residual ridge resorption is term to describe the diminishing quantity and quality of the residual ridge after teeth are removed.

The consequences of residual ridge resorption includes loss of sulcus depth and width, transformed facial aesthetics, altered vertical dimension of occlusion, altered position of the mental foramen, and altered inter-arch relationship. All these factors have some bearing on the success of the denture.

Both retention and stability are factors that majorly rely on the structural integrity exhibited by the underlying residual ridge. However this structural integrity is short lived as the residual ridge undergoes resorption, causing a reduction in its size. The rate and amount of resorption of bone varies from individual to individual. There is variation of resorption in the same individual at different times and even at the same time in different areas of the residual ridge.

It has been established in the past that the process of residual ridge resorption is multifactorial in nature. [3] Atwood suggested that the factors responsible for the process of resorption could be a combination of Anatomic factors, Metabolic factors, Functional factors and Prosthetic factors.

The multifactorial nature makes it is difficult to predict the rate and amount of the residual ridge resorption. It is of clinical significance to understand the rate and amount of resorption to predict the prognosis of the removable prosthesis with respect to the retention, stability and support, the frequency of recall appointments and also to predict the success of grafting procedures in extremely resorbed cases.

With the introduction of resorption markers it is possible to understand the rate of resorption. These markers measure the levels of biochemical markers of bone resorption in the form of free and urine deoxypyridinoline (DPD), N-telopeptides (NTx) and C-telopeptides (CTx). [4] However, the resorption makers serve as a relatively expensive technique and require constant monitoring. Hence there is a need for a simpler and cost effective technique to predict the resorption of bone.

Calcium is the fifth most common element in the body. It is the main constituent in bone and forms about 1.5% of the total body weight. 99% of calcium is present in the bones and the rest is present in the plasma. Calcium in bones is present in two types. There is a small quantity of readily exchangeable calcium and a larger quantity of stable calcium. It is the larger stable quantity of calcium that helps in the deposition and resorption of the bone thereby causing remodelling. Hence there is a need to understand the physiological metabolism of calcium. The direct relation of calcium to the resorption of bone could hence prove as an important diagnostic tool to study resorption.

Creatinine is spontaneously formed from creatine in muscle and released into the bloodstream at a fairly constant rate. It is removed from the body by largely by glomerular filtration although additionally there is a small amount of creatinine removed by renal tubular secretion and gastro-intestinal losses. In any individual with stable renal function the scatter of serum creatinine concentrations is very small. It also has a constant rate of excretion through a period of 24 hours.

This study was therefore carried out to find the correlation between a simple, cost effective 24 hour urinary calcium-creatinine ratio and the clinical finding of completely edentulous patients.


  Materials and Methods Top


Completely edentulous male patients of the age group of 56 years to 88 years (Mean age: 71 years) that visited the Department of Prosthodontics between October 2010 and June 2011 were selected for the study. The period of edentulism ranged from 6 months to 22 months with the average period being 12.5 months. The inclusion criteria for the study were completely edentulous male patients who had never worn any removable dental prosthesis before with no relevant medical history and who were willing to participate in the study. Female patients were not included to the study due to the postmenopausal osteoporotic changes frequently diagnosed in them.

Primary impressions were made using medium fusing impression compound (Y-Dents impression compound, MDM Corporation, Delhi) in a stock metal tray. These impressions were then poured in impression plaster (Dental plaster, Kalabhai, KalabhaiKarson Pvt. Ltd., Mumbai) and the primary casts were obtained. A custom tray was fabricated for each of these patients using self-cure acrylic resin tray material (M. P. Sai Enterprise, Mumbai). Border molding was performed using sectional technique in low fusing impression compound (DPI Pinnacle tracing sticks, Dental Products of India, Mumbai) and a wash impression was made in eugenol free impression paste (Cavex Outline, Cavex, RW Haarlem, Netherlands). Temporary record bases and occlusal rims were made in self-cure acrylic resin (DPI Cold Cure acrylic, Dental Products of India, Mumbai) and modeling wax (Elite Modelling wax, Elite dental products, Nanded) on the master casts (Dental stone, Kalabhai, KalabhaiKarson Pvt. Ltd., Mumbai) obtained from the final impressions.

Standardized orthopantomographs (OPG) were taken (Gendexorthoralix 9200) using a metallic ball of 5 mm diameter [Figure 1] and were incorporated within the occlusal rims at 74kv, 10 mA for 12 seconds.
Figure 1: Standardization of orthopantomographs

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Two measurements were made on a lead acetate paper on the OPGs [Figure 2]:
Figure 2: Tracings on orthopantomographs to measure resorption index

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IM- Distance from the lower margin of the mental foramen to the inferior border of the mandible.

IC- Distance from the crest of the residual alveolar ridge to the inferior border of the mandible.

A urine sample was collected from each patient. Random samples were taken, where the patient was asked not to collect the 1st urine sample of the day and collect all the subsequent samples for the next 24 hours. The testing of the samples was done in an auto analyzer machine (RX Imola, RANDOX International, U.K.) at DeenanathMangeshkar Hospital in Pune [Figure 3].
Figure 3: Autoanalyzer machine

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  Results Top


The readings obtained from the 24 hours urinary calcium-creatnine ratio were made to correlate with the resorption index of the patients [Table 1]. The inclusion criterion for the study was patients with no relevant medical conditions. However, in the course of the testing there were a few subjects that were not included as a part of the study due to an increased value of creatinine levels more than the normal range. This could be due to undetected renal conditions.
Table 1: Results

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A direct relation was seen between patients with lower resorption index and lower 24 hours urinary calcium-creatnine ratio [Graph 1]. These findings were clinically also related to the cases which had undergone a marked amount of reduction in the residual alveolar ridges with respect to the width and height.



Also, a direct relation was seen when the patients presented with higher 24 hours urinary calcium-creatnine ratio and greater resorption index. These patients presented with good height and width of the residual ridges.

Carlsson had illustrated that the resorption of bone for over a 5 year post extraction period was found to be maximum in the first 2 years of the period of edentulism. All the subjects tested in the study had a period of edentulism of less than 2 years. Hence it was clear that the time since the extraction was done did not have an effect on the reduction on the ridges.


  Discussion Top


Resorption of residual alveolar ridges is a well-documented process. The rate of resorption varies among different individuals and within the same individual at different times. Authors have suggested different factors responsible for the resorption process. [3],[5],[6] Irrespective of the etiology, the management of cases of residual ridge resorption is more or less the same. However in spite of the extensive knowledge we have on the etiology of resorption the information on prediction of the same is still inadequate.

The use of resorption markers has given us a technique to understand the resorption of bone. These markers study the breakdown products of the bone matrix in the form of urine or serum by-products. However these markers are very technique sensitive and are relatively expensive.

The use of a simple, cost effective urine analysis was done in this study. A 24 urinary Calcium- Creatinine ratio was estimated by urine analysis for each patient. Completely edentulous male patients were only selected for the study to rule out the potential post-menopausal osteoporosis in women, which would have influenced the study. Also patients with no existing prosthesis were selected. It has been understood that poorly fabricated prosthesis could induce pressure resorption due to the unfavourable stress distribution. [7] Many systemic diseases and their pharmacological managements have also been causes for resorption of bone. [5],[6] Hence to understand the resorption pattern better, patients with relevant medical histories were not included in the study.

Calcium is a vital element for the physiological functioning of the body. It is a fundamental element necessary to form electrical gradients across membranes and the main constituent in bone. Under normal physiologic conditions, the concentration of calcium in serum and in cells is tightly controlled. The excess of calcium is excreted through urine or faeces. Asplinfound a correlation in urinary calcium excretion and resorption of bone. [8] Nordin proposed the use of the ratio of the calcium to creatinine concentration in random urine specimens as a convenient index of urinary calcium excretion. [9] In this ratio creatinine serves as a reference standard by virtue of its relatively constant excretion rate throughout the 24 hours. Hence a 24 urinary calcium- creatinine ratio was evaluated.

The purpose of the study was to correlate the urinary calcium- creatinine ratio with the clinical situation of the patients with respect to the amount of resorption. More often than not, we discuss the amount of residual ridges in the form of "good, fair or poor" ridges. However, quantifying the residual ridges must be made imperative in terms of communication. Many radiographic studies have been done to study the amount of the residual alveolar ridges. [10],[11] However it was Ortman in 1989 who gave a classification that correlated to the amount of residual ridge present in accordance to the radiographic findings. [12] He suggested the use of two measurements IC and IM as discussed earlier to get a ratio termed as resorption index. [13] Based on the index the ridges could be classified as residual ridges undergoing mild, moderate and severe resorption [Table 2].
Table 2: Resorption index by ortman

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  Conclusions Top


Within the limitations of the pilot study it was observed that:

  1. There is a direct relation between the resorption of the bone and the calcium-creatinine levels of the edentulous subjects.
  2. Patients with clinically good ridges had higher calcium-creatinine ratio and higher resorption index and vice versa.
  3. The calcium-creatnine ratio in conjunction with the resorption index can be used as a simple and cost effective diagnostic tool.


Clinical significance

Within the limitations of the pilot study it could be proved that:

  1. Patients with a higher resorption index and higher calcium-creatinine ratio are likely to undergo resorption at a slower rate.
  2. Patients with a higher resorption index and lower calcium-creatinine ratio are likely to undergo resorption at faster rate.
  3. Patients with a lower resorption index and higher calcium-creatinine ratio would have lesser amount of resorption further.
  4. Patients with a lower resorption index and lower calcium-creatinine ratio are likely to undergo even more resorption in the future.


However, further investigation would be required with a larger sample size to use the calcium-creatnine ratio in conjunction with the resorption index as a diagnostic index.

 
  References Top

1.Kingsmill VJ. Post extraction remodelling of the adult mandible. Crit Rev Oral Biol Med 1999;10:384-404.  Back to cited text no. 1
    
2.The Glossary of Prosthodontic Terms. J Prosthet Dent 2005;94:10-92.  Back to cited text no. 2
    
3.Atwood DA. Some clinical factors related to rate of resorption of residual ridges. J Prosthet Dent 1962;12:441-50.  Back to cited text no. 3
    
4.Kushida K, Takahashi M, Kawana K, Inoue T. Comparison of markers for bone formation and resorption in premenopausal and postmenopausal subjects, and osteoporosis patients. J Clin Endocrinol 1995;80:2447-50.  Back to cited text no. 4
    
5.Baylink DJ, Wergedal JE, Yamamoto K, Manzke E. Systemic factors in alveolar bone loss. J Prosthet Dent 1974;31:486-505.  Back to cited text no. 5
    
6.Pearce G, Tabensky DA, Delmas PD, Baker HW, Seeman E. Corticosteroid-induced bone loss in men. J Clin Endocrinol Metab 1998;83:801-6.  Back to cited text no. 6
    
7.Carlsson GE. Clinical morbidity and sequelae of treatment with complete dentures. J Prosthet Dent 1997;79:17-23.  Back to cited text no. 7
    
8.Asplin JR, Donahue S, Kinder J, Coe FL. Urine calcium excretion predicts bone loss in idiopathic hypercalciuria. Kidney Int 2006;70:1463-7.  Back to cited text no. 8
    
9.Wills MR. The urinary calcium/creatinine ratio as a measure of urinary calcium excretion. J Clin Pathol 1969;22:287-90.  Back to cited text no. 9
    
10.Atwood DA, Coy WA. Clinical, cephalometric, and densitometric study of reduction of residual ridges. J Prosthet Dent 1971;26:280-95.  Back to cited text no. 10
    
11.Atwood DA. Post extraction changes in the adult mandible as illustrated by microradiographs of midsagittal sections and serial cephalometric roentgenograms. J Prosthet Dent 1963;13:810-24.  Back to cited text no. 11
    
12.Ortman LF, Hausmann E, Dunford RG. Skeletal osteopenia and residual ridge resorption. J Prosthet Dent 1989;61:321-5.  Back to cited text no. 12
    
13.Zmys³owska E, Ledzion S, Jedrzejewski K. Factors affecting mandibular residual ridge resorption in edentulous patients: A preliminary report. Folia Morphol 2007;66:346-52.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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