COMPARATIVE ANALYSIS OF THE FIRST PERMANENT MOLARS CARIES PREVALENCE IN YOUNGER AND OLDER SCHOOL CHILDREN

Sažetak Uvod. Podaci o stanju zdravlja prvih stalnih molara kod dece našeg područja su oskudni. Stoga se nameće potreba za podrobnijom analizom stanja zdravlja ovih zuba kod dece našeg regiona, kao i za utvrđivanjem najkritičnijeg perioda u kome dolazi do značajnog porasta prevalencije karijesa ovih zuba. Cilj. Cilj istraživanja bio je da se na uzorku dece sa teritorije Niša izvrši uporedna analiza prevalencije, proseka i strukture karioznih, ekstrahovanih i plombiranih prvih stalnih molara kod dece mlađeg u odnosu na decu starijeg školskog uzrasta. Materijal i metode. Istraživanjem je obuhvaćno 1119 ispitanika, uzrasta od 7 do 14 godina. Ispitanici su prema uzrastu podeljeni u dve grupe: na ispitanike mlađeg i ispitanike starijeg školskog uzrasta. Stomatološki pregled učenika izvršen je upotrebom sonde i stomatološkog ogledalca, a stanje zdravlja ispitivanih zuba registrovano je upotrebom KleinPalmer-ovog KEP sistema. Rezultati. Istraživanjem su utvrđene visoke vrednosti parametara prevalencije karijesa prvih stalnih molara koje rastu sa uzrastom ispitanika. Kod ispitanika uzrasta 8, 9 i 10 godina registrovane su statistički značajno veće vrednosti ispitivanih parametara prevalencije karijesa ispitivanih zuba u odnosu na ispitanike uzrasta od 7 godina. Kod ispitanika starijeg školskog uzrasta, statistički značajno veće vrednosti registrovane su samo za KIz i KIp-a i to samo kod ispitanika uzrasta od 14 godina u odnosu na ispitanike uzrasta od 11 godina. Sa uzrastom ispitanika, procenat karioznih prvih stalnih molara se smanjuje a povećava procenat plombiranih i ekstrahovanih prvih stalnih molara. Zaključak. Rezultati pokazuju da je period između 7 i 10 godina starosti dece najkritičniji i najznačajniji za primenu preventivno profilaktičkih mera i postupaka, koji imaju za cilj očuvanje zdravlja prvih stalnih molara. Ključne reči: prvi stalni molari, prevalencija karijesa, deca Abstract Introduction. The data on the health-condition of the first permanent molars among children in our region is scarce. Therefore, the need for more thorough analysis of the state of health of these teeth in the children from our region imposes itself, along with the need to determine the most critical period in which a significant increase in caries prevalence of these teeth takes place. Aim. The aim of the research was to perform a comparative analysis of the prevalence, average rate and structure of decay, missed and filled first permanent molars in the children of the younger school age in relation to those of the older school age. Material and methods. The research included 1.119 examinees, aged from 7 to 14 years. Examinees were divided into two groups according to their age: examinees of the younger school age and older school age. Dental check-up of the students was performed by means of a dental probe and mirror and the health condition of the examined teeth was registered by means of Klein-Palmer’s DMF system. Results. The research determined high values of the examined parameters of the first permanent molars caries prevalence which increases with the age of the examinees. In the examinees of the age of 8, 9, and 10, statistically more significant values of the examined teeth caries prevalence parameters were registered, in relation to the examinees of seven years of age. In the examinees of the older school age, statistically significantly higher values were registered only for TCI and ACI and only in the examinees aged 14 in relation to the examinees aged 11. With the age, the percent of decay is decreases, while the percent of filled and extracted first permanent molars increases. Conclusion. Results show that the period between 7 and 10 years of age is the most critical and the most important period for the implementation of preventive-prophylactic measures aimed to preserve the health of the first permanent molars.


Introduction
The first permanent molars are most often the first permanent teeth that come through in a child's mouth.These functionally significant human teeth are also very significant indicators of both the caries activity of permanent teeth and the efficacy of applying preventive, pro phylactic and therapeutic mesures 1,2 .Due to everything listed above, the examination of car ies prevalence in these teeth was the research subject of many authors who concluded that the first molars caries prevalence rises continu ously along with the age of the examinees.Re searches have shown that already at the age of six, when this tooth generally comes through, between 5% and 12% of children has at least one decayed, missed or filled (DMf) first per manent molar. 3,4 he percent of children aged 12 who have at least one DMf on the first per manent molars, mainly exceeds 50%.However, most data on the first molars caries prevalence is outdated and it mainly refers to the devel oped countries, whereas the data on the healthcondition of these teeth among children in our region is rather scarce.Therefore, the need for more thorough analysis of the state of health of the first permanent molars in children from our region imposes itself, along with the need to de termine the most critical period in which a sig nificant increase in caries prevalence of these teeth takes place.

Aim
The aim of this research was to perform a comparative analysis of the prevalence, av erage rate and structure of decay, missed and filled (DMf) first permanent molars in the chil dren of the younger school age in relation to those of the older school age.

Material and methods
This research included the students of three elementary schools located at the territory of the city of Niš.School principals together with the parents of the students-examinees gave written consent for students' participation in this research, and the Ethical Committee of the faculty of Medicine University of Niš ap proved the research (No. 01-244-4/2012).
Kod ispitanika mlađeg školskog uzrasta, starosti 7 godina, KIo iznosi 37.81%, KIz 19.33% a KIp 0.78.Sa uzrastom ispitanika, vrednosti ispitivanih parametara prevalencije karijesa prvih stalnih molara rastu i u uzrastu od 10 godina dostižu vrednosti za KIo 68.02%, KIz 49.82% KIp 1.99.Kod ispitanika uzrasta 8, 9 i 10 godina registrovane su statistički značajno veće vrednosti ispitivanih parametara prevalencije karijesa prvih stalnih molara into two groups according to their age: the first group comprised 559 examinees of the younger school age, ranging between 7 and 10 years of age, whereas the second group consist ed of 560 older school age examinees, ranging between 11 and 14 years of age.All the three primary schools, the students of which were in cluded in the research, are in possession of their own dental service with a dental practice, so that the students were under the constant dental supervision.
General dental check-up of the students was performed in the premises of the school's dental practice, by means of a dental probe and mirror, in the January-June period of the year 2012.The general check-up was performed by a pre ventive and pediatric dentistry specialist and a doctor on this specialization, and the health condition of the first permanent molars was reg istered by means of Klein-Palmer's DMf sys tem.The check-up included only the examin ees in whom all the first four permanent molars had come through.The caries prevalence was expressed in statistical coefficients: the person caries index (PCI) and teeth caries index (TCI); by an index and measure of average values, average caries index (ACI) and an indicator of the structure of decay, missed and filled (DMf structure) teeth.
Statistical analysis of the obtained data was done in the Microsoft Excel 2007 programme.The data was displayed by standard methods of descriptive statistics (estimated presence, aver age value (X), standard deviation (SD)).Sta tistical significance of the obtained results was determined by the Student's t test.The obtained results were displayed by tables and graphs.

Results
In the examined groups of children of younger and older school age, high values of the examined parameters of caries prevalence (PCI, TCI, and ACI) were found, which in creases with the age of the examinees (Table 1).
In the examinees of the younger school age, aged 7, PCI was 37.81%, TCI was 19.33% and ACI was 0.78.The examined parameters values of the first permanent molars caries prevalence increased with the age of the examinees, and at the age of 10 they reached the values for PCI 68.02%, TCI 49.82%, ACI 1.99 In the examin ees of the age 8, 9, and 10, statistically more of significant values of the examined first perma nent molars caries prevalence parametres were u odnosu na ispitanike uzrasta od 7 godina (Tabela 2 i 3).Nije registrovana statistički značajna razlika u prevalenciji karijesa prvih stalnih molara između ispitanika uzrasta 10 i 11 godina, odnosno na prelazu mlađeg u stariji školski uzrast (Tabela 2 i 3).
A statistically significant difference in the first permanent molars caries prevalence was not registered between the examinees of 10 and 11 years of age, that is, at the transition from younger to older school age (Table 2 and 3).
In the examinees of older school age, high values of the examined first permanent molars caries prevalence parameters were registered, which increased with the age of the examinees (Table 1).At the age of 11, PCI was 74.35%, TCI 52.40% and ACI 2.09, and in the examin ees aged 14, the examined parameters reached the maximum values -for PCI 79.86%, TCI 66.19% and ACI 2.65.However, statistically significantly higher values were registered only for TCI and ACI and only in the examinees aged 14, in relation to the examinees aged 11 (Table 2 and 3).
At all the ages of the examinees, a higher first permanent molars caries prevalence was registered in girls (Table 4).

Diskusija
Sprovedeno istraživanje, kojim su bila obuhvaćena deca mlađeg i starijeg školskog uzrasta sa teritorije Grada Niša, ukazuje na visoku prevalenciju karijesa prvih stalnih extracted permanent molars increases (Graph 1).Among the examinees of the younger school age, in the period between 7 and 9, an unfavor able DMf structure was registered (a higher per cent of caries-infected in relation to the percent of the cured first permanent molars), whereas in the examinees of the younger school age of 10 and all the examinees of the older school age a favorable DMf structure was registered (a higher percent of cured than the percent of caries-infected teeth).The percent of extracted first permanent molars increases with the age of the examinees.At the age of 7, 1.08% of the first permanent molars were extracted, whereas in the examinees at the 14 years of age, even 9.28% of the extracted first permanent molars were registered (Graph 1).No statistically sig nificant difference was registered in the DMf structure of the first permanent molars between boys and girls, regardless of their age (p>0.05).
Analizom strukture KEP-a utvrđeno je da se sa uzrastom ispitanika procenat karioznih prvih stalnih molara kontinuirano smanjuje a povećava procenat saniranih (plombiranih i ekstrahovanih) prvih stalnih molara.Nepovoljna struktura KEP-a je registrovana samo kod ispitanika mlađeg školskog uzrasta, starosti od 7 do 9 godina, dok ja ona u svim ostalim uzrastima bila povoljna.Kako su ovim permanent molars in seven-year-olds 5 and the children of the younger school age of our re gion 6 , from 2000, that is, 2004, suggest a sig nificant reduction of caries prevalence in these teeth.However, regardless of these data, due to the outdated data scarcity on the first permanent molars caries prevalence in the children of our region aged from 7 to 14, it is difficult to de termine the total efficiency of these preventive programmes application in our region by moni toring these teeth caries prevalence.
The results obtained by this research show that the first permanent molars caries preva lence increases with the examinees age, the fact to which some other authors also pointed 7,8 .At the younger school age, with the exam inees of 8, 9 and 10 years of age, statistically more significant the first permanent molars car ies prevalence was registered, compared to the children aged 7. The obtained results can be ex plained by the fact that the mentioned period corresponds to the phase of post-eruptive matu ration when teeth sensitivity to the effect of car iogenic stimulations is the highest 9 .Therefore, this statistically significant increase of the first permanent molars caries prevalence at the age of 8-10 years of age can be considered expected and in accordance with the findings of other au thors according to whom the sensitivity of the first permanent molars to cariogenic stimuli is highest at 1-4 years after eruption, after which it decreases 10 .As for the children of the older school age, with the increase in the age of the examinees continuously goes the increase in the first permanent molars caries prevalence, but without any statistical significance.In this period, statistically significantly higher values were registered only for TCI and ACI in the ex aminees aged 14 in relation to the examinees aged 11.
The first permanent molars caries preva lence at all the ages of the examinees was high er in the girls compared to boys, which is in accordance with the data from the available lit erature (11), so the obtained results point to the necessity for a somewhat more intensive med ically-educational work with girls compared to boys of all ages.
Analyzing the DMf, it was determined that with the examinees age, the percent of the car ies-infected first permanent molars decreased, while the percent of the cured (filled and ex tracted) first permanent molars increased.An unfavourable DMf structure was only regis tered in the examinees of the younger school age, 7-9 years old, whereas in all the other ages it was a favorable one.Since this research in istraživanjem obuhvaćeni učenici osnovnih škola koje poseduju svoju stomatološku službu, dobijeni rezultati nedvosmisleno pokazuju kontinuiranu brigu školskih stomatologa i istovremeno potvrđuju značaj školske stomatološke nege u očuvanju usta i zuba, na šta su i ranije ukazali drugi autori 12,13 .
• U starijem školskom uzrastu, statistički značajno veće vrednosti registrovane su samo cluded the students who have their own den tal service, the obtained results unequivocally point to continuous care of school dentists, at the same time confirming school dental care significance in preserving the mouth and teeth, to which the other authors have pointed be fore 12,13 .
Nevertheless, apart from that, what is alarm ing is the fact that the percent of the extracted first permanent molars is being continually increasing with examinees age and that in the examinees of the age of 14, the value of even 9.28% is reached.Due to the extraordinary sig nificance of the first permanent molars, the ex traction of these teeth for orthodontic reasons is very rare and limited 14 .On the other hand, neg ative consequences of the extraction of the first permanent molars are numerous, and primarily conditioned by the number and time of their extraction.The research by Albadri 15 et al. has shown that even in 70% of cases, caries with bad prognosis is the reason for the extraction of the first permanent molars, and in 11% of cases that is molar-incisor hypomineralization.In addition, this group of authors suggested that the average time of the first permanent molars extraction is the age of 11, which is substan tially later than the time recommended in case when the extraction of these teeth is necessary, and that is the age between year 8 and 10 16 .By means of this research it was found that at younger school age, on average, about 1% of the first permanent molars is annually extract ed, and at the age of 11 2.45% of the first per manent molars is extracted.furthermore, with every year of age, the percent of the extracted first permanent molars is almost doubled and at the age of 14 it reaches the value of even 9.28%.It can be assumed that caries complications are the main reasons for extracting the first perma nent molars in the examined group of children.

Conclusion
This research determined the following: • A high first permanent molars caries prevalence in the examined group of children, which grows with the examinees age.
• The most greatest increase in caries prevalence of these teeth was registered in younger school age, where as in the examinees aged 8, 9 and 10 statistically significantly higher parameter values of caries prevalence were registered in relation to those under the age of 7.
• In the older school age, statistically significantly higher values were registered only for TCI and ACI of children of 14 in relation to those of 11 years of age.
• With the age of the examinees, the percent of caries-infected teeth decreases and the percent of the cured (filled and extracted) teeth increases.
• A high percent of the extracted teeth was registered, the values of which will be in the older school age doubled on annual basis.By this research, the significance and the role of school dental care in preserving oral health was unequivocally affirmed, but this re search has also pointed to the necessity of ap plying prophylactic measures and actions the purpose of which is to preserve the health of the first permanent molars.Based on the results, it can be considered that the period between 7 and 10 years of age is the most critical and the most important period for the application of preven tive-prophylactic measures aimed to preserve the health of these, biologically and function ally, very important teeth.

Table 1 .
Decay prevalence of 1 st permanent molars in examined group in children by Klein-Palmer Tabela 2. Odnos KIo i KIz između određenih uzrasnih grupa

Table 4 .
Decay prevalence relation of 1 st permanent molars between girls and boys in the examined group 6olara u svim ispitivanim uzrastima.Već u uzrastu ispitanika od 7 godina KIo prvih stalnih molara iznosi 37.81%, KIz 19.33% a KIp 0.78.Ispitivani parametari prevalencije karijesa prvih stalnih molara rastu sa uzrastom ispitanika, u uzrastu od 10 godina skoro da udvostručuju svoje vrednosti da bi u uzrastu od 14 godina dostigle maksimalne vrednosti i to za KIo 79.86%, KIz 66.19% i KIp 2.65.Međutim, podaci o prevalenciji karijesa prvih stalnih molara kod dece školskog uzrasta drugih zemalja uglavnom su starijeg datuma, pa je te rezultate nemoguće uporediti sa rezultatima koji su dobijeni ovim istraživanjem.S druge strane, zahvaljujući jakim preventivnim programima, u zemljama razvijenog sveta beleži se konstantno opadanje prevalencije karijesa stalnih zuba, a samim tim i prvih stalnih molara, što dodatno otežava komparaciju dobijenih rezultata.Slično je i sa pojedinim zemljama našeg okruženja, kao što je npr.Hrvatska, gde je 2007.godineregistrovanaznačajnaredukcijaprevalencije karijesa prvih stalnih molara u odnosu na 1977.godinu,štoautoritumačejakim preventivnim programima koji su sprovedeni tokom ovog perioda 2 .Podaci o stanju zdravlja prvih stalnih molara sedmogodišnjaka5i dece mlađeg školskog uzrasta našeg regiona6iz first permanent molars caries prevalence at all the ages examined.Already, in the examinees aged 7, PCI of the first permanent molars is 37.81%, TCI 19.33% and ACI 0.78.The exam ined parameters of the first permanent molars caries prevalence increase with the examinees age, at the age of 10 they almost double their value, so that they would reach, at the age of 14, their maximum values for PCI79.86%,TCI 66.19% and ACI 2.65.However, the data on the first permanent molars caries prevalence among the schoolage children in other countries are mostly outdated, so it is impossible to compare those results with the ones obtained by this re search.On the other hand, due to strong preven tive programmes, in the developed countries a constant decrease in the permanent teeth caries prevalence is registered, and at the same time of the first permanent molars as well, which addi tionally makes the comparison of the obtained results even more difficult.It is a similar situa tion with the countries of our surrounding as is the case with Croatia where a significant reduc tion of the first permanent molars caries preva lence was registered, in relation to 1977, which was interpreted by authors by strong preventive programmes which were conducted during this period 2 programmes which were conducted during this 2 programmes which were conducted during this .The data on the health state of the first Grafikon 1. Struktura KEP-a prvih stalnih molara u grupi dece uzrasta od 7-14 godina Figure 1.DMF structure of 1 st permanent molars in the group of children aged 7-14 years st permanent molars in the group of children aged 7-14 years