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Table of Contents   
ORIGINAL ARTICLE  
Year : 2022  |  Volume : 25  |  Issue : 5  |  Page : 521-525
Loss of dental tissue after restoration or sealing of occlusal carious lesions: 3-4-year results of randomized clinical trials


1 Department of Social and Preventive Dentistry, Faculty of Odontology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
2 Department of Surgery and Orthopedics, Faculty of Odontology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
3 Faculty of Medicine and Dentistry, Catholic University of Louvain, Brussels, Belgium, Brazil
4 Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, Brazil

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Date of Submission06-Apr-2022
Date of Decision18-May-2022
Date of Acceptance25-May-2022
Date of Web Publication05-Jul-2022
 

   Abstract 


Context: Although preservation of the tooth structure is quoted as the main advantage of sealing of carious lesions, there are no long-term studies comparing the maintenance of dental tissue after restoration or after caries sealing.
Aim: To measure the radiographically visible loss of dental tissue after conventional restoration and sealing of carious lesions.
Subjects and Methods: This study was a secondary analysis of two randomized controlled clinical trials, one conducted in Brazil and another in Belgium, which evaluated two different therapies for the treatment of occlusal carious lesions in permanent teeth: sealant (SE) without previous carious tissue removal or restoration (RE) with total removal of carious dentin. The greater depth and width of sealed carious lesions and restorations were compared.
Statistical Analysis: The independent t-test was used to compare therapies at different time points, while the paired t-test was used to compare the same therapy over time.
Results: Carious lesions in the RE and SE groups showed similar measurements at baseline (P > 0.05). Over time, significantly greater loss of tooth structure was observed in the RE group than in the SE group. No increase in lesion depth or width was observed in the SE group, suggesting no progression of sealed lesions.
Conclusion: Sealing of carious lesions resulted in greater preservation of dental tissue.

Keywords: Dental caries; dental radiography; dental restoration; dental sealant; randomized clinical trial

How to cite this article:
C. Carraro RL, Fontanella V, Carvalho JC, Alves LS, Maltz M. Loss of dental tissue after restoration or sealing of occlusal carious lesions: 3-4-year results of randomized clinical trials. J Conserv Dent 2022;25:521-5

How to cite this URL:
C. Carraro RL, Fontanella V, Carvalho JC, Alves LS, Maltz M. Loss of dental tissue after restoration or sealing of occlusal carious lesions: 3-4-year results of randomized clinical trials. J Conserv Dent [serial online] 2022 [cited 2022 Sep 25];25:521-5. Available from: https://www.jcd.org.in/text.asp?2022/25/5/521/349910



   Introduction Top


The conventional restorative treatment of carious lesions is based on the total removal of carious tissue and restoration (RE). RE fails over time and demands multiple replacements throughout the patient's life, weakening the dental structure and ultimately decreasing tooth longevity. This process was described by Elderton[1] as the “repetitive restorative cycle” and by Qvist[2] as the “death spiral.” In this context, conservative treatments aiming at the maximum preservation of dental tissues were proposed, such as sealing of carious lesions. A reduction in bacterial counts was observed after different sealing periods.[3],[4],[5]

Clinical trials have evaluated the effectiveness of sealing cavitated dentin lesions, reaching the outer half of dentin thickness. In a 10-year follow-up study, Mertz-Fairhurst et al.[6] showed survival of conventional amalgam REs similar to that of cavitated lesions without removal of carious tissue. Later, Bakhshandeh et al.[7] showed that sealing is effective, while the sealants (SEs) remain intact and well adapted. Although SEs have failed more often than REs, half of the sealed teeth did not require resin RE after 7 years of monitoring.[8] The 3–4-year randomized clinical trial by Alves et al.[9] showed success rates of 76% and 94% for SEs and REs, respectively. This study also showed that the sealing of carious lesions was able to control the caries process despite the need for regular follow-ups to control SE retention. These results provided evidence that small- and medium-sized cavitated lesions could be arrested through sealing and that they did not require immediate RE. Thus, traditional restorative treatment could be postponed for several years or even avoided, thereby increasing tooth survival.[8]

Although preservation of the tooth structure is quoted as the main advantage of sealing of carious lesions, there are no long-term studies comparing the maintenance of dental tissue after RE or caries sealing. Therefore, this study aimed to measure the radiographically visible loss of dental tissue after conventional RE with total removal of carious dentin and sealing of carious lesions without removal of carious tissue.


   Subjects and Methods Top


This study was a secondary analysis of two randomized controlled clinical trials, one conducted in Porto Alegre, Brazil, and another in Brussels, Belgium, which evaluated two different therapies for the treatment of occlusal carious lesions in permanent teeth: SE without previous carious tissue removal or RE with total removal of carious dentin. All carious lesions would be referred to restorative treatment due to the presence of a cavity with no possibility of biofilm control. Interproximal radiographs were used to evaluate the maximum depth of the lesions, which were located up to the outer half of the dentin.

Sample

A total of 75 patients aged 8–43 years (median, 19 years) were included, 49 underwent treatment at the Faculty of Odontology, Porto Alegre, southern Brazil, and 26 underwent treatment at the Saint-Luc University Hospital, Brussels, Belgium, totaling 106 teeth. The recruitment phase lasted for 12 months in Porto Alegre and 72 months in Brussels.

The Porto Alegre sample consisted of 54 teeth that were randomly assigned to the SE (n = 28) or RE (n = 26) groups. The Brussels study used a split-mouth design; therefore, each patient had one tooth assigned to the SE group (n = 26) and one to the RE group (n = 26). Radiographs were taken at baseline and follow-up periods of 10–20 and 25–46 months. Only patients who underwent radiographic follow-up with the possibility of measurements (without superposition and correct vertical and horizontal angulations) were included.

Interventions

The intervention used in this study was described previously.[9] Briefly, the occlusal surface was cleaned with a pumice/water slurry and Robinson bristle brushes. Local anesthesia was administered prior to tooth isolation. The teeth were then randomly assigned to the SE or RE groups.

Further, the SE was placed directly over the carious dentin, and no previous caries removal or invasive technique was performed in the SE group. The cavity was conditioned with 37% phosphoric acid gel for 30 s, followed by cavity washing and drying. The SE material was applied to the occlusal caries with an exploratory probe and light cured for 20 s.

In the RE group, after removal of carious dentin according to the clinical hardness criteria (to firm dentin[10]), enamel and dentin were conditioned with 37% phosphoric acid gel for 30 s in enamel and 15 s in dentin, followed by cavity washing and drying. An adhesive system was applied to the enamel and dentin cavity walls, and the teeth were restored with light-cured composite resin using the incremental technique.

Radiographic evaluation

Standardized bitewing radiographs were obtained using a positioner. Digital radiographs were obtained using phosphor storage plates, which were read immediately after exposure.

The images were exported using dbsWin®4 software and subsequently displayed on a monitor screen for radiographic measurements. All radiographs received the “Caries 2” program filter before being exported to standardize the brightness and contrast. Adobe Photoshop CC® version 2017 1.1 (Adobe Systems, San Jose, CA, USA) was used for analysis. The measurements were performed according to a method described previously in the literature.[11] Some images required geometric alignment owing to small differences in the projection angles, and the same software was used for correction. For this purpose, a reference point was positioned in a clearly distinguishable structure, such as the enamel–cement line (ECL), which was defined as a landmark in both the images.

To measure the carious lesion before treatment (baseline), the radiolucent area after sealing (SE group) and RE (RE group), the shallowest and deepest points of the lesion/RE, were demarcated. When it was not possible to identify the most superficial dentin point, the cusp that was not affected by the lesion was considered for evaluation. A line perpendicular to the ECL was then drawn, joining the two already demarcated points [[Figure 1], line AC]. The relative dentin depth of the lesion and the relative dentin depth of the RE were expressed as the percentage of the total length of the coronary dentin [[Figure 1], line AB]. The larger portions of the lesion/RE were marked with two points, and a parallel line to the ECL passing through the points was drawn subsequently [[Figure 1], line DE]. The relative dentin width of the lesion and the relative dentin width of the RE were expressed as percentages of the total width of the ECL.
Figure 1: Illustration of measurements of dentinal depth and width of occlusal carious lesions (a) and restoration (b) in radiographic images. ECL: Enamel–cement line; A-B: Total depth of coronary dentin; A-C: Depth of caries lesion/restoration; D-E: Width of caries lesion/restoration

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Reliability and blinding

All measurements were performed by a single researcher (RLCC) in triplicate for each tooth, with a minimum time interval of 1 week.

Prior to the measurements, each tooth was cut out from the radiograph, so that the examiner could not identify whether the radiograph was from the baseline or follow-up periods (10–20 or 25–46 months). In addition, the examiner was blinded to the place of origin of the radiographs (Porto Alegre or Brussels), experimental group (baseline radiographs), and different follow-up periods.

Statistical analysis

Reproducibility of the measurements was assessed using the intraclass correlation coefficient (ICC). The mean of the three measurements was calculated and used for statistical analysis. The normality of the data was verified using the Kolmogorov–Smirnov test. The independent t-test was used to compare SEs and REs at different time points. The paired t-test was used to compare the same therapy over time. The level of significance was set at 5%.


   Results Top


The reproducibility of the measurements was considered high for all measurements (ICC ≥0.84).

[Figure 2] illustrates the study flowchart. In the SE group, 14 radiographs without possibility of measurements were detected and excluded; eight and seven patients were not assessed at the 10–20- and 25–46-month follow-ups, respectively. In the RE group, 10 radiographs without possibility of measurements were detected and excluded; 9 and 22 patients were not assessed at the 10–20- and 25–46-month follow-ups, respectively. Therefore, the total number of cases analyzed was 82 at baseline (40 SE and 42 RE), 65 at the 10–20-month follow-up (32 SE and 33 RE), and 53 at the 25–46-month follow-up (33 SE and 20 RE).
Figure 2: Flowchart of the study

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[Table 1] shows the measurements of the carious lesions before (baseline) and after treatment (10–20- and 25–46-month follow-ups). At baseline, all lesions had similar depth and width measurements (P > 0.05). Comparing the same therapy over time, restorative treatment resulted in significant loss of dental tissue in depth and width, while sealing of carious lesions resulted in no further tissue loss (similar radiolucent areas were observed at baseline and both follow-up periods). In addition, no increase in lesion depth or width was observed over time, suggesting no progression of sealed lesions. Comparing both therapies, conventional restorative treatment resulted in greater loss of dentin tissue in depth and width than sealing of carious lesions.
Table 1: Relative depth and width of occlusal caries lesions (baseline), restorations, and sealed lesions at 10-20-month and 25-46-month follow-up periods (mean %±standard deviation)

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   Discussion Top


The present study investigated the loss of dental tissue due to placement of a conventional RE compared to that due to sealing of carious lesions using data derived from two randomized controlled clinical trials. The results demonstrated that total carious dentin removal according to the hardness criteria followed by RE resulted in a significant loss of dental tissue. In contrast, sealing of lesions without removal of carious tissue was able to control caries progression with no further loss of dental tissue.

Cavitated lesions are usually treated with total caries removal to remove bacteria that invade the tissue and prevent lesion progression, thus increasing the longevity of the REs and maintaining pulp vitality.[12] Despite advances and modifications in restorative materials, REs have limited longevity, requiring replacement over time. Summarizing the results of 30 long-term prospective studies (≥5 years) in a meta-analysis, Beck et al.[13] concluded that the mean annual failure rate of resin REs in the posterior teeth was 1.97%. In a systematic review including eight articles published between 2005 and 2013, Ástvaldsdóttir et al.[14] demonstrated that one in every 100 REs should be replaced annually and that the survival rate of the REs decreased over time. The highest chance of failure occurred at 62 months. Therefore, RE replacement is a common procedure in general dental practice and is responsible for increasing the loss of tooth structure at each procedure, leading to tooth weakening.[14] Each RE replacement enlarges the cavity, and the subsequent RE is more complex, time-consuming, and costlier than the initial one. Consequently, with a greater number of faces involved, it will have shorter longevity and may have a deleterious effect on the pulp, leading to endodontic treatment. Thus, the restorative cycle has long-term detrimental consequences for dental health.[1],[2] The importance of adopting conservative therapies to manage dental caries has been recognized in the literature.[15] In this sense, the results of the present study show that sealing of carious lesions can be an alternative to conventional REs. No further increase in lesion depth or width was observed in the SE group at the 25–46-month follow-up. Although SEs may have a higher fracture rate than REs and conventional restorative treatment may be necessary in the future, it is possible to presume that tooth longevity is greater due to the postponement of a more invasive approach. Moreover, a reduction in lesion size can be expected with a longer follow-up period. Alves et al.[16] followed up sealed carious lesions for 10 years and observed a significant increase in the radiopacity of the remaining demineralized tissue after 10 years of monitoring; however, no difference was detected after 3 years.

When there is no possibility of cleaning the carious cavity, dental caries progress due to the access of bacteria to the substrate. Since a carious lesion is sealed, access to the external environment is blocked, thus controlling bacterial proliferation and arresting disease progression.[8],[9] This ability to inactivate the caries process was studied by Theilade[4] in a clinical trial that evaluated the effect of sealing on the microflora of noncavitated human molar occlusal fissures. The author concluded that the preventive effect of SEs may be due to the lack of fermentable carbohydrates for the remaining bacteria to accumulate acid in cariogenic concentrations, thus decreasing the number of viable bacteria. This result was corroborated by a meta-analysis that evaluated the effect of fissure SEs on the level of bacterial contamination.[5] Maltz et al.[17] showed that sealing of carious dentin resulted in lower levels of infection than traditional dentin caries removal based on the hardness criteria. Clinical studies have also demonstrated the possibility of arresting the progression of cavitated lesions after cavity sealing.[6],[7],[8],[9] The present study is the first to quantitatively demonstrate the absence of progression of sealed carious lesions on a long-term basis. Thus, the application of resin SE on cavitated occlusal carious lesions with radiolucent images restricted to the outer half of dentin can avoid the removal of carious tissue prior to conventional RE. In addition to biological advantages, it is noteworthy that the sealing technique is simpler, less time-consuming, and less stressful than the restorative technique, which are important aspects to be considered when treating specific age groups.[18]

Among the strengths of this study, we emphasize the high reproducibility of the examiner and the fact that all measurements were performed blinded and in triplicate. In addition, this is the first study to show that the final size of a RE is significantly greater than that of the original radiographically assessed carious lesions. Although radiographs can underestimate the loss of mineral tissue[19] and this could justify the greater depth and width of the REs that those of the lesions, no changes were observed in the SE group, implying that sealed lesions were properly arrested and that REs could have been avoided in these patients. A possible limitation of this study is that a smaller number of cases were evaluated at the 25–46-month follow-up in the RE group than in the SE group (20 vs. 33 teeth). We recognize this fact; however, we believe this has not affected the study findings since RE is a stable condition that is not presumed to change over time. In contrast, the long-term follow-up of sealed lesions is of greater importance due to possibility of lesion progression. Finally, the lack of three-dimensional information on radiographs is an intrinsic limitation of radiographic methods.


   Conclusion Top


  • Sealing of carious lesions resulted in greater preservation of dental tissue, that is, maintenance of the radiographically visible size of the lesion
  • Sealing of carious lesions was able to control lesion progression over time
  • Restorative treatment resulted in a greater loss of dental tissue.


Financial support and sponsorship

The study was financially supported by the Brazilian National Council of Technological and Scientific Development, Ivoclar/Vivadent (São Paulo, Brazil) and Caulk/Dentsply (Rio de Janeiro, Brazil).

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Elderton RJ. Preventive (evidence-based) approach to quality general dental care. Med Princ Pract 2003;12 Suppl 1:12-21.  Back to cited text no. 1
    
2.
Qvist V. Longevity of restorations: 'The death spiral'. In: Fejerskov O, Nyvad B, Kidd E, editors. Dental Caries: The Disease and Its Clinical Management. Hoboken: Wiley-Blackwell; 2005. p. 387-401.  Back to cited text no. 2
    
3.
Handelman SL, Washburn F, Wopperer P. Two-year report of sealant effect on bacteria in dental caries. J Am Dent Assoc 1976;93:967-70.  Back to cited text no. 3
    
4.
Theilade E, Fejerskov O, Migasena K, Prachyabrued W. Effect of fissure sealing on the microflora in occlusal fissures on human teeth. Arch Oral Biology 1977;22:251-9.  Back to cited text no. 4
    
5.
Oong EM, Griffin SO, Kohn WG, Gooch BF, Caufield PW. The effect of dental sealants on bacteria levels in caries lesions: A review of the evidence. J Am Dent Assoc 2008;139:271-8.  Back to cited text no. 5
    
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Mertz-Fairhurst EJ, Curtis JW Jr., Ergle JW, Rueggeberg FA, Adair SM. Ultraconservative and cariostatic sealed restorations: Results at year 10. J Am Dent Assoc 1998;129:55-66.  Back to cited text no. 6
    
7.
Bakhshandeh A, Qvist V, Ekstrand KR. Sealing occlusal caries lesions in adults referred for restorative treatment: 2-3 years of follow-up. Clin Oral Investig 2012;16:521-9.  Back to cited text no. 7
    
8.
Qvist V, Borum MK, Møller KD, Andersen TR, Blanche P, Bakhshandeh A. Sealing Occlusal dentin caries in permanent molars: 7-years results of a randomized controlled trial. JDR Clin Trans Res 2017;2:73-86.  Back to cited text no. 8
    
9.
Alves LS, Giongo FC, Mua B, Martins VB, Barbachan E Silva B, Qvist V, et al. A randomized clinical trial on the sealing of occlusal carious lesions: 3-4-year results. Braz Oral Res 2017;31:e44.  Back to cited text no. 9
    
10.
Innes NP, Frencken JE, Bjørndal L, Maltz M, Manton DJ, Ricketts D, et al. Managing carious lesions: Consensus recommendations on terminology. Adv Dent Res 2016;28:49-57.  Back to cited text no. 10
    
11.
Bakhshandeh A, Ekstrand KR, Qvist V. Measurement of histological and radiographic depth and width of occlusal caries lesions: A methodological study. Caries Res 2011;45:547-55.  Back to cited text no. 11
    
12.
Schwendicke F. Removing carious tissue: Why and how? In: Schwendicke F, Frencken J, Innes N, editors. Caries Excavation: Evolution of Treating Cavitated Carious Lesions. Vol. 27. Basel: Karger; 2018. p. 56-67.  Back to cited text no. 12
    
13.
Beck F, Lettner S, Graf A, Bitriol B, Dumitrescu N, Bauer P, et al. Survival of direct resin restorations in posterior teeth within a 19-year period (1996-2015): A meta-analysis of prospective studies. Dent Mater 2015;31:958-85.  Back to cited text no. 13
    
14.
Ástvaldsdóttir Á, Dagerhamn J, van Dijken JW, Naimi-Akbar A, Sandborgh-Englund G, Tranæus S, et al. Longevity of posterior resin composite restorations in adults – A systematic review. J Dent 2015;43:934-54.  Back to cited text no. 14
    
15.
Carounanidy U, Sathyanarayanan R. Dental caries: A complete changeover, PART III: Changeover in the treatment decisions and treatments. J Conserv Dent 2010;13:209-17.  Back to cited text no. 15
[PUBMED]  [Full text]  
16.
Alves LS, Fontanella V, Damo AC, Ferreira de Oliveira E, Maltz M. Qualitative and quantitative radiographic assessment of sealed carious dentin: A 10-year prospective study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:135-41.  Back to cited text no. 16
    
17.
Maltz M, Henz SL, de Oliveira EF, Jardim JJ. Conventional caries removal and sealed caries in permanent teeth: A microbiological evaluation. J Dent 2012;40:776-82.  Back to cited text no. 17
    
18.
Nadig RR, Usha G, Kumar V, Rao R, Bugalia A. Geriatric restorative care – The need, the demand and the challenges. J Conserv Dent 2011;14:208-14.  Back to cited text no. 18
[PUBMED]  [Full text]  
19.
Wenzel A, Fejerskov O, Kidd E, Joyston-Bechal S, Groeneveld A. Depth of occlusal caries assessed clinically, by conventional film radiographs, and by digitized, processed radiographs. Caries Res 1990;24:327-33.  Back to cited text no. 19
    

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Correspondence Address:
Dr. Luana Severo Alves
Department of Restorative Dentistry, School of Dentistry - UFSM, AV. Roraima, 1000 Camobi, 97105-900, Santa Maria, Rio Grande Do Sul
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcd.jcd_194_22

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