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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 16  |  Issue : 2  |  Page : 283-289

Effect of concentrated acids on teeth: A forensic approach; An In-vitro study


1 Department of Oral Pathology and Microbiology, School of Dental Sciences, Forensic Odontology, Krishna Institute of Medical Sciences Deemed to be University, Karad, Maharashtra, India
2 Department of Public Health Dentistry, School of Dental Sciences, Forensic Odontology, Krishna Institute of Medical Sciences Deemed to be University, Karad, Maharashtra, India

Date of Submission05-Apr-2018
Date of Decision25-Jan-2020
Date of Acceptance03-Feb-2020
Date of Web Publication18-Oct-2021

Correspondence Address:
Dr. Vidya Kadashett
Department of Oral Pathology and Microbiology, Forensic Odontology, School of Dental Sciences, Krishna Institute of Medical Sciences Deemed University, Malkapur, Karad - 415 110, Satara, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 110.4103/jdmimsu.jdmimsu_32_18

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  Abstract 


Background: The proceedings of destroying the body of human by putting in acid or some other injurious materials in order to prevent any individual identification is drawing a great deal of importance in forensic field. The idea of such crime is to destroy any physical evidence of cause of death, time interval of death to body identification, and victim identification. Teeth are also good reservoirs for the identification of individuals by morphological as well as identification by mitochondrial DNA extraction. Aims and Objectives: To assess the morphological changes and duration of dissolution of teeth from different acids. Materials and Methods: Concentrated hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid were employed for tooth. Results: Results showed that compared to sulfuric acid, HCl and HNO3 have more destructive capacity. Conclusion: Sulfuric acid, HNO3, and HCl criminals may be used to destroy the person identification; still, the individuals can be identified using teeth because it is the strongest structure of the human body and can preserve some structures even after exposure to the concentrated acids.

Keywords: Acid-immersed teeth, forensic odontology, forensic sciences, hydrochloric acid, nitric acid, sulfuric acid


How to cite this article:
Kadashett V, Shivakumar K M, Baad R, Vibhute N, Belgaumi U, Bommanavar S, Kamate W. Effect of concentrated acids on teeth: A forensic approach; An In-vitro study. J Datta Meghe Inst Med Sci Univ 2021;16:283-9

How to cite this URL:
Kadashett V, Shivakumar K M, Baad R, Vibhute N, Belgaumi U, Bommanavar S, Kamate W. Effect of concentrated acids on teeth: A forensic approach; An In-vitro study. J Datta Meghe Inst Med Sci Univ [serial online] 2021 [cited 2021 Dec 4];16:283-9. Available from: http://www.journaldmims.com/text.asp?2021/16/2/283/328468




  Introduction Top


Forensic odontology is defined as “that branch of forensic medicine which in the interest of justice deals with the proper handling and examination of dental evidence and with the proper evaluation and presentation of the dental findings.” Forensic science refers to areas of endeavor that can be used in a judicial setting and accepted by the court and the general scientific committee to separate truth from untruth.[1]

In day-to-day life, the nature of crime has changed, by using fire and acid attack or chemical attack. A forensic scientist always encounters new problems and challenges in the process of identification of persons. Nowadays, criminals are using acids to destroy bodies in order to avoid any personal identification. A forensic scientist needs to know whether it is possible to destroy the human body partially or totally by immersing it in an acid and, if so, how much time is necessary for its complete destruction. Another important question is whether there are any measures of identifying the affected individual from the residual remains.[2] Literature search revealed that there are very few studies that have actually focused on the issue of destruction of the human body by chemical means and the issue of positive identification after acid dissolution. There is a brief mention in the Italian journal Archivio di Medicina Legale of an experimental animal destruction in an acidic environment.[3] The identification of dental hard tissue remains is of prime importance when the deceased person is skeletonized, decomposed, burned, or dismembered.[4] Various kinds of acids at various concentrations were used to compare different decalcification methods for teeth.[5] It is well known that forensic odontological techniques help in the identification of an individual. Since the natural teeth are the strongest and most durable of all tissues, they can persist even long after other skeletal structures have been destroyed by physical agents and with chemical means. Further, it is now possible to extract DNA from the teeth even decades after death. It is possible to employ these identification techniques until there has been complete destruction of the teeth.[6],[7]

The aim of this study was to find and compare the approximate time taken for total destruction of a tooth after immersion in different concentrated acids. The objective was to observe the morphological changes in natural human teeth when they were kept immersed in different acids.


  Materials and Methods Top


A total of 30 specimens containing single-rooted teeth specimens are used for the study. All teeth were noncarious and had been extracted because of periodontal reasons. Acids used in this study include 25 ml of aqueous solution of hydrochloric acid (HCl), 25 ml of aqueous solution of nitric acid (HNO3), and 25 ml of aqueous solution of sulfuric acid (H2SO4), with 25 ml each for tooth specimens. Samples of tooth specimens were immersed in 25 ml of each acid solution and observed.

Specimens were divided into three groups, as follows:

  1. Thirty-seven percent HCl group: 10 extracted tooth specimens
  2. Sixty-five percent HNO3 group: 10 extracted tooth specimens
  3. Ninety-six percent H2SO4 group: 10 extracted tooth specimens.


All specimens were immersed separately in different containers containing three different acids. At various intervals (15 min, 30 min, 1 h, 2 h, 4 h, and 8 h, till the samples get completely dissolved in the respective solution), the samples were taken out of the containers and any morphological changes and noted changes and time of interval have been observed, and then they were then photographed and placed back in the containers. The specimens were under observation until they had completely dissolved or completely precipitated. Morphological changes were observed in the following points: effervescence, color alterations, transparency, disintegration, complete dissolution, and precipitation. Each specimen's morphology based on macroscopic was noted at every time interval.


  Results Top


For a tooth placed in concentrated HCl, effervescence was seen in 10 min for teeth. No color changes have been seen in teeth specimens. Transparency was seen after 4 h in teeth specimens. Disintegration was seen at 6 h and started dissolving, tooth completely dissolved in 18–20 h [Table 1] and [Figure 1], [Figure 2], [Figure 3], [Figure 4, [Figure 5].
Table 1: Sequential morphological changes along with duration in teeth after the immersion of specimens in 37% hydrochloric acid

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Figure 1: Effervescence in tooth with hydrochloric acid

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Figure 2: Transparency in tooth with hydrochloric acid at 3 h

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Figure 3: Disintegration of tooth with hydrochloric acid at 8 h

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Figure 4: Complete dissolution of tooth in hydrochloric acid at 18 h

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Figure 5: Yellow discoloration of tooth in nitric acid at 15 min

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Tooth placed in 65% HNO3 showed yellowish discoloration in the tooth within 15 min. Transparency was seen in tooth only within the first 2–4 h. Disintegration started at 5 h till 10 h in tooth. Tooth had started dissolving at 12 h and was completed at 16 h [Table 2] and [Figure 6],[Figure 7],[Figure 8].
Table 2: Sequential morphological changes along with duration in teeth after the immersion of specimens in 65% nitric acid

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Figure 6: Transparency of tooth in nitric acid at 2 h

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Figure 7: Disintegration of tooth in nitric acid at 7 h

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Figure 8: Complete dissolution of tooth in nitric acid at 16 h

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Tooth is placed in 96% H2SO4 showed effervescence seen immediately within 5–15 min brown discoloration seen in both tooth white precipitation continued with fragmentation and complete dissolution observed at 14 h. In tooth, white precipitation started at 5 h and continued with fragmentation at 12 h. Morphology of the tooth was retained even after 80 h complete dissolution of tooth take place at130 h [Table 3] and [Figure 9],[Figure 10],[Figure 11],[Figure 12],[Figure 13],[Figure 14].
Table 3: Sequential morphological changes along with duration in teeth after the immersion of specimens in 95% sulfuric acid

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Figure 9: Brown discoloration of tooth in sulfuric acid at 15 min

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Figure 10: White precipitation of tooth in sulfuric acid at 12 h

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Figure 11: Fragmentation of tooth in sulfuric acid at 20 h

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Figure 12: Fragmentation of tooth in sulfuric acid at 42 h

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Figure 13: Fragmentation of tooth in sulfuric acid at 80 h

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Figure 14: Fragmentation of tooth in sulfuric acid at 120 h

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  Discussion Top


Acid attacks on victims are a very common practice among gangsters in South East Asia. Acids are known to be used in laboratory procedures and in some criminals are used to erase the personal identification. In such a case, the various tissues affect the determination of age and gender of the affected individuals. Human dentition serves viable evidence in this scenario. The tooth has been used as weapons and under certain circumstances may leave information about the identity of the biter. Dental professionals have a major role to play in keeping accurate dental records and providing all necessary information so that legal authorities may recognize malpractice, negligence, fraud or abuse, and identity of unknown individuals.[8] Literature search revealed that there are very few studies that have actually focused on the issue of destruction of the human body by chemical means and the issue of positive identification after acid dissolution.[3] The present study summarizes how teeth are strong enough to help in identifying the individuals even in acidic conditions. The aim was to find and compare the approximate time taken for total destruction of hard tissues after immersion in acids and observe the morphological changes in natural human teeth when they were kept immersed in acids.

Literature search revealed that there are very few studies that have actually focused on the issue of destruction of the hard tissues such as tooth by chemical means. The present study shows the total destruction of tooth in 37% HCl was 14–16 h, for 65% HNO3 was 13–14 h, and for 95% H2SO4 was almost 120 h for complete dissolution. These results show that tooth is stronger than bone it can withstand for some hours even complete immersion of tooth specimen not only acid spill or splashing attack. These results are in concordance with that of the study conducted by Jadhav et al.[9] The use of dentition in forensic approach for identification of individuals and gender determination in this study is justified by the evidence that the natural teeth are the most durable of all tissues. They can persist even long after other skeletal structures have been destroyed by physical agents. The morphological characteristics help the investigator in deciding whether the tooth is of human or animal origin, single or multirooted, deciduous or permanent, and restored or not. Duration and morphological changes of tooth with different concentrated acids are summarized in [Table 1], [Table 2], [Table 3].

Thus, different destructive capacities of the different acids in tooth are clear and differences were observed in the present study. The information derived in this study on the morphological changes observed in teeth after particular periods of immersion in an acid solution [Table 1], [Table 2], [Table 3] can be utilized for identification of the acid used and to infer the approximate duration of immersion in the acid. Morphological changes may vary when the different concentrations and different acids are used in different tissues; however, it must be noted that the concentrated acids that we have used are the ones that are most commonly available commercially. Some other factors have also to be considered. Minimum of 80–100 l of acid is required for complete dissolution of a body.[6] Criminals will always be guided in their choice by ease of availability of the acid, cost, and efficiency of action. They will be more likely to use an acid that is easily available, cheap, and with the ability to destroy the body rapidly. Being hardest and chemically the most stable tissue in the body, teeth can be an important forensic investigative medium in both living and nonliving populations. Teeth are also good reservoirs of both cellular and mitochondrial DNA; however, the quality and quantity of DNA obtained varies according to the environment the tooth has been subjected to.[10],[11],[12] Thus, based on these observational results, we conclude that commonly used acids such as HCl, HNO3, and H2SO4 that would be most likely used in such crimes. Recognizable morphological appearances of teeth persisted for 8 h in HCl, for 10 h in HNO3, and for up to 85 h in H2SO4. Among the three acids, the complete dissolution of teeth was faster in concentrated HCl and was the slowest in H2SO4. This is in agreement with the previous studies done by Mazza et al.[6] and Jadhav et al.[9] The time taken for dissolution varied in these studies as the acids were of varying concentrations. Morphological changes in the teeth can help the forensic investigator to deduce the acid used and the time elapsed since immersion of the body in the acid until it can be further corroborated with biochemical investigations. From the observation of the present study, it is concluded that hard tissues such as teeth do not react the same way in all-acid environment. Teeth placed in the concentrated HCl and concentrated HNO3 form soluble salts of calcium chloride and calcium nitrate, respectively, making them to dissolve in toto. Tooth placed in concentrated H2SO4 forms insoluble calcium sulfate salt failing to dissolve completely forming an insoluble precipitate.[6],[9] Hence, human dentition can serve as great evidence when a person is affected with concentrated acids aiming at destruction of personal identification.

By the above observation, a positive diagnosis can be made with a tooth, when a victim's body is treated with concentrated H2SO4 for some hours (80–100 h). Comparatively, if bodies are immersed in the concentrated HCl and concentrated HNO3 (within 8–10 h) such kind of situations where it is impossible to identify the dental structures, other investigations can be considered, such as:

  • Chemical/histological analysis of the residues
  • DNA analysis (mitochondrial) of the residues
  • Chemical analysis of the final residual solution.


DNA analysis, which has brought about a revolution in the field of forensic science, including forensic dentistry, anthropology, and archeology, has made identification easier and more accurate.[13],[14],[15]

The limitation of this study is that effects of acids surrounding the teeth, dental restoration, and prosthesis have not been assessed. Admittedly, the present study does not take into account the influences of all possible factors that may be present in real-life conditions. For example, the protection provided by the soft and hard tissues surrounding the teeth makes the root part more resistant to acid insults.


  Conclusion Top


HCl is the most commonly used acid; it can be used to destroy the human body completely. The crimes of this nature, morphological changes in teeth can help the forensic investigator to deduce the time elapsed since immersion of the body in the acid. By keeping in mind the likely choices of the criminal and by observing the morphological changes in the teeth, it is possible to deduce which acid has been used to destroy the body and helpful in the identification of individuals. However, the final decision on which acid has been used should be based on biochemical tests.

From this study, we observed that sulfuric acid, HNO3, and HCl criminals may be used to destroy the person identification; still, the individuals can be identified using teeth because it is the strongest structure of the human body and can preserve some structures even after exposing to the concentrated acids. Further studies can be performed such as to assess if DNA from the tooth pulp can be extracted in such teeth specimens.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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O'Shaughnessy PE. Introduction to forensic science. Dent Clin North Am 2001;45:217-27, vii.  Back to cited text no. 1
    
2.
Raj M, Boaz K, Srikant N. Are teeth evidence in acid environment. J Forensic Dent Sci 2013;5:7-10.  Back to cited text no. 2
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3.
Danesino P, Alonzo M, Carlesi G. Experimental evaluation of the biological samples dissolution performed by three different acids: Preliminary results. Archivio di Medicina Legale 1998;1:23-6.  Back to cited text no. 3
    
4.
Avon SL. Forensic odontology: The roles and responsibilities of the dentist. J Can Dent Assoc 2004;70:453-8.  Back to cited text no. 4
    
5.
Kuś M, Ossowski A, Zielińska G. Comparison of three different DNA extraction methods from a highly degraded biological material. J Forensic Leg Med 2016;40:47-53.  Back to cited text no. 5
    
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Mazza A, Merlati G, Savio C, Fassina G, Menghini P, Danesino P. Observations on dental structures when placed in contact with acids: Experimental studies to aid identification processes. J Forensic Sci 2005;50:406-10.  Back to cited text no. 6
    
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Samsuwan J, Somboonchokepisal T, Akaraputtiporn T, Srimuang T, Phuengsukdaeng P, Suwannarat A, Mutirangura A, Kitkumthorn N. A method for extracting DNA from hard tissues for use in forensic identification. Biomed Rep 2018;9:433-38.  Back to cited text no. 7
    
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Seth RK, Mishra G, Raj A, Sing S, Chaubey S. Effect of concentrated acids on soft and hard tissue: a macroscopic analysis. University J Dent Scie 2015;3:20- 4.  Back to cited text no. 8
    
9.
Jadhav K, Gupta N, Mujib BR, Amberkar VS. Effect of acids on the teeth and its relevance in postmortem identification. J Forensic Dent Sci 2009;1:93-8.  Back to cited text no. 9
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10.
Sowmya K, Sudheendra U, Khan S, Nagpal N, Prathamesh S. Assessment of morphological changes and DNA quantification: An in vitro study on acid-immersed teeth. J Forensic Dent Sci 2013;5:42-6.  Back to cited text no. 10
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Lijnen I, Willems G. DNA research in forensic dentistry. Methods Find Exp Clin Pharmacol 2001;23:511-7.  Back to cited text no. 11
    
12.
Presecki A, Brkic H, Primorac D, Drmic I. Methods of preparing the tooth for DNA isolation. Acta Stomatol Croat 2000;34:21-4.  Back to cited text no. 12
    
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Ginther C, Issel-Tarver L, King MC. Identifying individuals by sequencing mitochondrial DNA from teeth. Nat Genet 1992;2:135-8.  Back to cited text no. 13
    
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Zappa J, Cieslik-Bielrcka A, Adwent M, Cieslik T, Sabat D. Comparison of different decalcification methods to hard teeth tissues morphological analysis. Dent Med Probl 2005;42:21-6.  Back to cited text no. 14
    
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Rothwell BR. Principles of dental identification. Dent Clin North Am 2001;45:253-70.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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