Aim: assessment of the caries damage of the second primary molars (SPrM) and the impact on the caries damage of the first permanent molar (FPM).
Material and method: retrospective study on dental files of 180 children (86 boys) aged between 6 and 11, examined and treated in the Pedodontics Department, Carol Davila University Bucharest during 2006-2020. Demographic data (age, sex) and data about SPrM and FPM dental status were selected from the dental files. The caries prevalence indices (IpSPrM, IpFPM), caries experience indices (dmf-t/-sSPrM, DMF-T/SFPM), pulpal involvement indices (pufaSPrM, PUFAFPM) were calculated. The statistical analysis was performed with the SPSS 20.0 program, using t-Test and ANOVA, p=0.05.
1. IpSPrM=100%; dmf-tSPrM=2.78±1.77 (dmf-tSPrMboys=1.91±1.48; dmf-tSPrMgirls=3.66±2.29; p<0.05); dmf-sSPrM=6.79±3.45 (dmf-sSPrMboys=7.02±6.44; dmf-sSPrMgirls=6.56±6.01; p>0.05); pufaSPrM=7±4.16(pufaSPrMboys=7.75±7.84; pufaSPrMgirls=6.25±6.32; p>0.05). 10.17% SPrM were caries-free, 2.11% with treated caries, 87.71% with untreated caries (36.23% occlusal, 32.04% mesial, 17.71% distal, 14.02% on other surfaces).
2. IpFPM=78.33%; DMF-TFPM=3.63±1.83 (DMF-TFPMboys=3.58±2.03; DMF-TFPMgirls=3.68±1.77(p>0.05); DMF-SFPM=4.36±1.91 (DMF-SFPMboys=4.22±1.84; DMF-SFPMgirls=4.51±2.81(p>0.05); PUFAFPM=0.5±1. 9.79% FPM were caries-free, 5.03% with treated caries; 85.17% with untreated caries (72.90% occlusal, 11.98% mesial, 15.12% on other surfaces).
- In the studied group SPrM’ and FPM’ caries experience was high.
- All SPrM present were carious, each patient having approximately 3 carious SPrM and 7 carious surfaces.
- The presence of distal caries on SPrM increased the risk of caries on the mesial surface of FPM.
- High carious experience in the primary dentition may be a predictor for carious experience in the permanent dentition.
Key words: second primary molars, first permanent molars, dental caries
It is well known that the presence of carious lesions in the primary dentition is a predictive factor for the appearance of caries in the permanent dentition, especially on the first permanent molar (FPM) [1,2]. Gray et al. (1991) showed that the existence of at least 3 carious primary molars at the age of 5 means an increased probability of caries on FPM at the age of 7 . Steiner et al., cited by Gray et al. , noted that a small number of healthy temporary molars at the age of 7-8 is the best predictor for a high caries risk in the permanent dentition.
Moreover, the literature reports that the mesial surface of FPM is more susceptible to carious attack than the proximal surfaces of other permanent teeth, primarily due to the presence of caries on the distal surface of the primary second molar (SPrM) [3,4, 5]. Thus, Mejare et al. (2001) showed that the risk of developing caries on the mesial surface of FPM is 15 times higher when there are caries on the distal surface of SPrM than when it is caries-free . Jafari et al. (2021) noted that carious lesions on the primary molars and especially on the SPrM had a very close correlation with the occurrence of caries on the FPM: when all the primary molars were caries-free, the neighboring FPM were caries-free, with a probability of 95.9%, and when only first primary molars or only SPrM were caries-free, the probability of caries-free FPM decreased to 92.2% .
Thus, the aim of this study was to assess the SPrM’ caries experience and the impact on the FPM’ caries experience in a group of children from a specialized clinic.
Material and method
A descriptive observational retrospective study was carried out on dental files of some patients examined and treated in a single dental office in Pedodontics Department, Carol Davila University Bucharest during 2006-2020.
The study group consisted of 180 children (86 boys) aged between 6 and 11 years (table I).
Table I. Distribution of patients per age (n)
The inclusion criteria were:
– patients aged between 6 and 11, with at least one FPM erupted on the arch;
– caries-free patients or with common caries pattern
– patients without associated general conditions (non-syndromic);
– patients with correctly and completely dental files.
The exclusion criteria were:
– patients with different ages from 6-11;
– patients with chronic general diseases;
– patients with illegible dental files.
The working method consisted in the analysis of the dental files and the recording of the data necessary for the study: the age and sex of the patients; the dental status of SPrM and FPM present on the arch at the time of examination: caries-free, with uncomplicated or complicated caries, with treated caries (correctly or incorrectly); distribution and topography of carious lesions.
The information was statistically processed using the SPSS 20.0 program. The following were calculated: caries prevalence indices (IpSPrM, IpFPM), caries experience indices (dmf-t/-sSPrM, DMF-T/SFPM), the pufaSPrM/PUFAFPM indices. The pufa/PUFA index is an index showing the degree of pulpal involvement. It is calculated by summing its components:
– the p/P component – records teeth with carious lesions affecting the pulp chamber or when the coronal tooth structures have been destroyed by the carious process and only roots or root fragments are left.;
– the u/U component – records the traumatic ulcerations that appear on the soft parts (buccal mucosa, jugular mucosa, tongue) due to the sharp edges of teeth with complicated caries, including root fragments;
– the f/F component – records the fistulas near the teeth with pulpal involvement;
– the a/A component – records the abscess starting from a tooth with pulp involvement .
The pulpal involvement index for SPrM was written in lowercase letters (pufaSPrM) and those for FPM in capital letters (PUFAFPM).
The distribution of dental caries was also assessed according to their severity and topography.
Statistical analysis was performed with t-Test and ANOVA, for a chosen level of statistical significance p=0.05.
- Caries experience of SPrM
Caries prevalence (IpSPrM)
The SPrM caries prevalence index (IpSPrM) was 100%, with all 180 patients having at least one carious SPrM at the time of examination.
Caries experience indices
The values for dmf-tSPrM and dmf-sSPrM indices were 2.78±1.77, respectively 6.79±3.45. According to gender, it was found that the differences were statistically significant for dmf-t and statistically insignificant for dmf-s: for boys dmf-tSPrM = 1.91±1.48 and dmf-sSPrM = 7.02±6.44; in girls dmf-tSPrM = 3.66±2.29 and dmf-sSPrM = 6.56±6.01.
The dmf-t/-sSPrM indices values were mainly given by d-tSPrM (64.74%) and d-sSPrM (89.83%) components (decayed tooth/ decayed surface). The analysis of dmf-t/-sSPrM indices by components is represented in table II.
Table II. dmf-t/sSPrM indices and their components
The pufaSPrM index had a mean value of 7±4.16, with pufaSPrMboys = 7.75±7.84 and pufaSPrMgirls = 6.25±6.32 (p>0.05). The mean value was mainly concentrated at the pSPrM component (pulpal involvement) – 91.42%: p=6.4±0.92; u=0; f=0.1±0.16; a=0.5±0.28.
Dental status of SPrM
From the 708 SPrM examined, 10.17% (n=72) were caries-free, 87.71% (n=621) were with untreated caries and 2.11% (n=15) were filled.
From the 621 SPrM with untreated caries 44.28% (n=275) were in boys and 55.71% (n=346) in girls (p<0.05), 49.59% (n=308) in the upper arch and 50.41% (n=313) in the lower one (p>0.05). The distribution of SPrM with untreated caries according to their topography is presented in table III.
|3 surfaces with the involvment of distal surface||20||3.22|
|3 surfaces without the involvment of distal surface||7||1.12|
Regarding the severity of dental caries, 90.98% (n=565) of SPrM had uncomplicated caries and 9.01% (n=56) complicated caries.
Among SPrM with uncomplicated caries (n=565): 84.77% (n=479) had superficial caries – 47.43% (n=268) in girls and 37.34% (n=211) in boys (p <0.05) – and 15.22% (n=86) deep caries –3.71% (n=21) in girls and 11.50% (n=65) in boys (p<0.05).
Among the 56 SPrM with complicated caries: 44.64% (n=25) were in girls and 55.36% (n=31) in boys (p<0.05), 48.21% (n=27) in the maxilla and 51.78% (n=29) in the mandible (p>0.05). 60.71% (n=34) SPrM had various forms of pulpitis and 39.28% (n=22) pulp necrosis. Regarding the pulpitis, 21 had acute pulpitis (61.76%) and 13 chronic (38.23%). Out of the 22 SPrM with pulp necrosis, 54.54% (n=12) presented simple pulp necrosis and 45.45% (n=10) complicated pulp necrosis – 36.36% (n=8) with acute apical periodontitis and 9.09% (n=2) with chronic apical periodontitis.
- FPM’ caries experience
Caries prevalence (IpFPM)
78.33% (141) of children had caries on FPM, 24.44% (44) on all 4FPM simultaneously.
Caries experience indices (DMF-T/SFPM)
The DMF-TFPM and DMF-SFPM indices had values of 3.63±1.83 and 4.36±1.91, respectively, with statistically insignificant differences according to sex: DMF-TFPMboys=3.58±2.03, DMF-TFPMgirls=3.68±1.77 (p>0.05); DMF-SFPMboys=4.22±1.84, DMF-SFPMgirls=4.51±2.81 (p>0.05). The values were mainly given by the D-TFPM (88.15%) and D-SFPM (91.74%) components (decayed tooth/ decayed surface): D-TFPM=3.20±1.91; M-TFPM=0.06±0.64; F-TFPM=0.37±1.25; D-SFPM=4±1.24; M-SFPM=0.05±0.51; F-SFPM=0.31±1.03.
The PUFAFPM index had an average value of 0.5±1, only 2 FPM having complicated caries.
Dental status of FPM
From the total of 715 FPM examined 9.79% (n=70) were caries-free, 85.17% (n=609) presented untreated caries and 5.03% (n=36) were already treated at the first visit in the clinic.
Among the 609 FPM with untreated caries, 51.88% (n=316) were in girls and 48.12% (n=293) in boys (p>0.05).41.21% (n=251) were in the upper arch and 58.78% (n=358) in the lower arch (p<0.05).
As regards the topography of the dental caries, the distribution is presented in table IV.
Table IV. Topography of carious lesions on FPM
|3 surfaces with the involvment of mesial surface||8||1.31|
99.67% (n=607) FPM had uncomplicated caries and only 0.33% (n=2) complicated caries.
Out of the 607 FPM with uncomplicated caries, 76.44% (n=464) had superficial caries – 40.19% (n=244) in girls and 36.26% (n=220) in boys (p>0, 05); 20.26% (n=123) medium caries – 10.54% (n=64) in girls and 9.71% (n=59) in boys (p> 0.05) – and 3.29% (n =20) deep caries – 1.31% (n=8) in girls and 1.97% (n=12) in boys (p> 0.05).
Complicated caries, existing only in boys, occurred on 2 FPM, one with total acute serous pulpitis, the other with total simple pulp necrosis.
The analysis of the information resulting from the data processing shows that the carious experience of the studied group aged between 6 and 11, both on SPrM and on FPM, is high. Thus, each child had approximately 3SPrM with approximately 7 surfaces affected by caries, which denotes an increased carious activity. In addition, of the total of 708 SPrM examined, more than 3/4 (87.71%) had carious lesions. Among them, 90.98% presented uncomplicated caries and 9.01% – complicated caries. These results can be explained by the fact that the children’s parents choose to go to the dentist later, usually in emergency, when advanced carious lesions are already present, because they do not give much importance to primary teeth because “they change anyway”. Honcala et al. (2011) found in Estonian children of aged 7-8 high percentages of cavity caries in dentin, especially at SPrM . Likewise, Zhang et al. (2014)  found that the most severe caries were on SPrM, the prevalence at this level being 52%. Steiner et al. (cited by Baginska et al., 2014)  raise an alarm stating that a small number of caries-free primary molars at children aged 7-8 causes a high caries risk in the permanent dentition.
Compared to the two arches, although with a statistically insignificant difference, the lower SPrM were more affected than the upper ones: 50.41% vs. 49.49%. Wyne (2008) found caries prevalence on the lower SPrM of 54.3% and 38.9% on the upper SPrM .
In the present study, in the context of increased caries involvement of SPrM, and 85.17% of the FPM present on the arch had carious lesions, the carious damage index values showing that each child had more than 3 FPM with caries on at least 3 surfaces. Leroy et al. (2005), in a research of 4468 children examined annually throughout primary school, concluded that the occurrence of cavity caries on FPM was clearly influenced by the status of the temporary molars and especially that of SPrM. Moreover, they noted that if all SPrM were carious and the child had poor hygiene, caries appeared on FPM 1-2 years after its eruption . Also, Chen et al. (2003), examining 100 6-year-old children, found that there was a positive and statistically significant correlation between dmf-t and DMF-TFPM (r=0.5629), showing the important role that caries damage has in the temporary dentition in predicting the occurrence of caries on permanent teeth .
Regarding the topography of the carious lesions on the SPrM, the present study noted that the most affected was the occlusal-proximal surface (49.75%) followed by the occlusal surface (36.23%). Corresponding to the latter, in the case of FPM 12% had the mesial surface affected. It should be emphasized that in the studied age group the mesial surface of FPM was statistically significantly more affected than the distal one, the presence of distal caries on SPrM being particularly important here. These results are also found in other similar studies. Mejare et al. (2000) noted that 64% of 9-year-old children had caries on one or more distal surfaces of SPrM . Skeie et al. (2004) showed that proximal carious lesions in primary molars were the most frequent, with the majority already in the dentin. They also claimed that 2 carious surfaces on SPrM at the age of 5 show that in the next 5 years new carious lesions will appear on other teeth, thus requiring periodic controls . In addition, Li and Wang (2002), in a study of a group of Chinese children, observed that 94% of children who developed caries at the FPM level also had caries on SPrM, 93.9% of them even on the mesial surfaces . Vanderas et al. (2004) demonstrated that the presence of caries on the distal surface of SPrM significantly influenced the appearance of caries on the mesial surface of FPM, their development rate being 95% . Mejare et al. (2001) established a relationship between caries damage to the distal surface of SPrM and the impact on the mesial surface of SPM, concluding that there is a greater risk of lesions occurring on the mesial surface of FPM when the distal surface of SPrM is affected . Leroy et al. (2005) found that the formation of carious lesions at the level of FPM is closely related to the status of SPrM . In their longitudinal study, Skeie et al. (2006) showed that at 10 years of age FPM was the most carious permanent tooth (91.8% of total DMFS). 45.7% of 10-year-old children had 1 or more mesial caries on FPM, with a positive and statistically significant correlation between carious lesions on SPrM at 5 years of age and those on FPM at 10 years of age (r = 0.5; p < 0.01) . In 2010, Topaloglu-AK and Eden found that dmft on temporary molars at the age of 6-7 was strictly correlated with DMF-TFPM at the age of 10-11 . In contrast, Baginska et al. (2014) and Donaria et al. (2017) found a weak correlation between caries on SPrM and those on neighboring FPM [11, 21] and Srinivasan et al. (2015) did not observe any statistically significant association between the two variables .
The results emerging from our study entitle us to state that the existence of caries on the distal/disto-occlusal surface requires, as a main objective, the prevention of caries grafting on the mesial surface of FPM, on the one hand by treating the lesion on SPrM, and on the other hand by applying prophylactic measures on FPM.
- Caries damage to SPrM and FPM in the studied sample was high.
- All SPrM present were carious, with each patient having approximately 3 carious SPrM and 7 carious surfaces.
- The presence of distal caries on SPrM increased the risk of caries on the mesial surface of FPM.
- High caries experience in the primary dentition may be a predictor for caries experience in the permanent dentition.
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