Onset of Dental Emergence Stages Among 4-15 Year-Old Nigerian Children: A Guide for Clinical Intervention

attained each of the stages earlier than male participants, P>0.05. Conclusion: The results show that female participants attained early mixed dentition, late mixed dentition, and adolescent dentition earlier than males. However, males had early attainment of the intermediate mixed dentition. The average age of the fully erupted first and second permanent molars also occurred earlier among the females. Therefore, individualized staging of the dentition stage is needed to guide the a p p r o p r i a t e t i m i n g o f t r e a t m e n t intervention.


INTRODUCTION
Thorough assessment of the developmental stages of an individual, whether via physiological development, skeletal development, or dental development and eruption, is invaluable in the diagnosis, treatment planning, and prognosticating treatment outcome in children, especially those at risk of growth disruption.Dental development involves the entire process of tooth formation beginning during the 5th week of intra-uterine life to the complete 1 closure of the root apex of the third molar.It has been adjudged to be the least developmental indicator affected by O b j e c t i ve : T h i s p r e s e n t s t u d y w a s conducted to determine the onset of the various dentition stages among a group of Nigerian children.

Materials and methods:
This was a crosssectional descriptive study.Data were collected over a fourteen-month period among clinically healthy 424 participants comprising 186 male and 238 females aged 4-15 years, and analyzed using SPSS statistics 22.0.The mean ages of onset of the various dental stages, the overall dental stages and the dental stages of each jaw were compared according to gender using unpaired t-test.Statistical significance level was set at P<0.05.

Results:
The average age of the fully established deciduous dentition was 4.61 ± 0.79 years among female participants and 5.00 ± 1.16 years in males, p=0.153.Females were also observed to have attained early mixed dentition, late mixed dentition, and adolescent dentition earlier than male participants.The average age of the fully erupted first and second molars were 9.76 ±2.36 years and 13.06 ± 1.71 years respectively, with female participants observed to have Nigerian Dental Journal | Vol 32 No. 2 2024 individual primary and permanent teeth while giving little attention to the dentition stages.The aim of this study was to determine the periods of onset of the dental stages using specified group of teeth as 15 described by Bjork et al and compare findings from this current study with results from other climes.In order to ascertain the timing of the dentition stage as reported in this study, it was compared to the eruption time of specific teeth in Nigerian children to d e t e r m i n e w h i c h d e n t i t i o n s t a g e corresponds with a particular eruption timing of specific teeth.

MATERIALS AND METHODS
This study utilized a cross-sectional design, comprising children who attended the orthodontic and paedodontic clinics over a fourteen-month period (June 2022 to August 2023).All the participants were clinically healthy, with no history of orthodontic treatment, and aged between 4 to 15 years.Children attending the clinic with obvious developmental anomaly like cleft lip and palate were excluded from the study.The authors obtained ethical approval from the Ethics and Research Committee of the Hospital Management Agency, and assent was also gotten from the study participants.Data Collection: The information obtained from the participants and/or their parents/guardians included chronological age and gender.

Assessment of dental emergence:
The authors conducted visual assessment of the dental emergence on the study participants while they were seated on a dental chair.For adequate visibility, each participant rinsed the oral cavity with water for 30 seconds, and, thereafter, the gingival tissue was cleaned with a sterile gauze.The oral cavity was then examined by the investigator (AO) using a mouth mirror and periodontal probe to identify emerging teeth.The dental development of the participants, which in this study is the dental emergence staging, was based on the gingival emergence/visibility of a set of teeth in the oral cavity, corresponding to the dental stages (DS).

Description of assessment tool (Appendix A):
The dental emergence staging was assessed  Also, this study showed that the mean age of the onset of eruption of the first permanent molars was earlier in females (6.77 ± 1.52 years) than in males (6.88 ± 1.64 years), p=0.702.The average age of the fully erupted first and second permanent molars were 9.76 ± 2.36 years and 13.06 ± 1.71 years respectively, with female participants observed to have attained each of the stages earlier than male participants, p > 0.05, (Table 3).
II.The individual is in DS 02, DS 2, or DS 4 even if not all the teeth concerned are present, provided that the reason for the absence of a tooth is extraction or dentition (developmental) anomaly.III.Recording only one of the stages implies that all the earlier stages are complete.If a new stage occurs before the previous one is complete -for example when a canine or premolar is visible before all the incisors are fully erupted -this finding will be recorded, as DS 1 and DS 3. IV.Document the molar eruption stage in addition to the anterior dental stage, using the definitions in Appendix A.
Also, for the purpose of sex differences, evaluation of the onset of dental emergence stages in the anterior and posterior segment of the maxilla and mandible were performed separately using the adjusted criteria (Appendix B), using a specially designed form to capture initial data for participants (Appendix C).

Data analysis:
The data collected from the questionnaires were coded and inputted into IBM SPSS statistics 22.0 (SPSS Inc., Chicago, Illinois, USA).Mean ages of onset of the various dental stages, overall dental stages, and the dental stages of each jaw were compared according to gender using unpaired t-test.The statistical significance level was set at p<0.05.

RESULTS
Over the fourteen-month period, data was collected from 424 participants comprising 186 males and 238 females (Table 1).Furthermore, the onset of the erupting first permanent molars to the stage of fully erupted first and second permanent molars were earlier in female participants when compared to the male participants, as shown in Table 5.I n t h e m a x i l l a r y d e n t i t i o n , f e m a l e participants attained fully established deciduous dentition with an average age of 5.04 ± 0.90 years compared to the male participants (5.28 ± 1.02years).Also, the average ages of onset of the early mixed (6.96 ± 1.01 years) and late mixed (10.21 ± 1.45years) and adolescent dentitions (12.69 ± 1.79 years) were earlier among female participants recruited for the study.However, this study shows that the maxillary dentition anterior to the molars in the intermediate dentition (7.93 ± 1.77) was earlier in male participants.The results also indicated that gender difference in the onset of the maxillary dentition stages anterior to the molar teeth were not statistically significant (Table 6).

Table 6: Comparison of the maxillary deciduous and the permanent dentition anterior to the molars according to sex
Considering the maxillary molar dentitions, the mean age of the onset of an erupting first permanent molars was earlier among male participants (6.92 ± 1.68 years) when compared to female participants.However, female participants in this study attained the full state of the erupted first molars (9.72 ± 2.45 years) earlier than male participants (9.76 ± 2.34 years), p=0.916.The same preponderance was observed, with the second molars attaining its fully erupted state in female participants (12.76 ± 2.16 years) when compared to male participants (13.37 ± 0.82 years).The differences observed in the mean ages of the onset of the dental stage of the maxillary molars in relation to gender were not statistically significant (Table 7).

Onset of Dental Emergence Stages Among 4-15 Year-Old Nigerian Children
Nigerian Dental Journal | Vol 32 No. 2 2024 among Swedish children (male, 6.17 years, and females 5.91 years), appeared to be delayed.Female participants in this present study attained late mixed dentition (DS3) and adolescent dentition (DS4) stages earlier than the male participants, which corroborates observations made from 16, 21-23 earlier researches.
However, period of onset of the intermediate mixed dentition (DS2) was observed to have been be earlier in male participants than female participants in our current study, which is at variance with

DISCUSSION
As far as orthodontic treatment is concerned, optimal timing is of paramount importance.This holds true for the determination of the onset of the various dental stages which [18][19][20] could influence the timing of intervention.Onset of dental eruption of the primary and permanent teeth have majorly been the focus dentition stages.This study reviewed the findings of the research in relation to the observations made in these other climes.Also, findings from this research were related to dental emergence of the deciduous and permanent teeth and the onset of dental eruption as reported among Nigerians.
The mean age of onset of early mixed dentition (DS1) recorded in this present study (males, 6.66 years, and females, 6.50 years), though comparable to the results onset of DS3 as reported by the authors appear to be earlier than the observations made in this study.A cross-sectional approach was employed to obtain data for this study, so it is possible that the exact period of the establishment of the dentition may have been earlier.The mean age of onset of the molars recorded in this study showed that females were also earlier in all the stages, which corroborates with results reported in 16,21,22 previous studies.

Onset of Dental Emergence Stages Among 4-15 Year-Old Nigerian Children
This study revealed that the first molar emerged (M0) and got to full occlusal contact (that is fully erupted, M1) quite earlier among the Swedish population (M0: males 6.17 years, and females 5.91 years; M1: males 8.30 years, and 7.97 years 16 for females) when compared to this current study.However, our research revealed that the mean ages of onset of the fully erupted second molar M2; (males 13.37 years, and 12.91 years in females) was quite comparable to findings reported among the Danish children (M2: males 13.37 years, and 12.82 The periods of onset of the dental stages were compared to dental eruption as reported in the literature.The intermediate mixed dentition (DS2) is described as the period when all the incisors are said to have T r e a t m e n t a n d p o s t t r e a t m e n t c r a n i o f a c i a l c h a n g e s a f t e r r a p i d maxillary expansion and facemask therapy.Am authors This difference could be accounted for by the h u g e d i f f e r e n c e i n t h e n u m b e r o f participants.In this study, time of onset of the intermediate mixed dentition (DS2) was observed to be largely comparable to the finding among the Norwegian, Danish, reported DS2 among male and female Danish children to be 8.72 years and 8.32 years respectively, while the 16 findings of Hagg & Taranger regarding Swedish children was 8.30 and 7.97 years, among males and females respectively.The onset of late mixed dentition stage (DS3) among Icelandic children were reported to be 9.48 years and 8.94 years in 22 males and females respectively, while 9.55 This could have accounted for the variations in the timing.The onset of the adolescent stage (DS4) w a s o b s e r ve d t o b e s i m i l a r t o t h e o b s e r v a t i o n s m a d e b y p r e v i o u s 21,22 researchers.Our study showed DS4 to be 12.91 years in males which could be likened 21 to 12.69 years in Danish male children, 12.92 22 years in Icelandic male children, and 12.60 23 years in Norwegian male children.In addition, the onset of DS4 in female participants in this study was 12.79 years, which is proportionate to 12.09 years in 21 Danish female children, 12.05 years in 22 Iceland female children, and 12.15 years in 23 Norwegian male children.

15 emerged.
In this study, the average age of DS2 for both males and females was 7.92 years.According to a study conducted among Nigerian children, the maxillary N. Treatment effects of reverse twinblock and reverse pull face mask on craniofacial morphology in early and late mixed dentition children.Orthod Craniofac Res 2017;20(03):134-139. 19.Baccetti T, Franchi L, McNamara JA Jr.

Onset of Dental Emergence Stages Among 4-15 Year-Old Nigerian Children
7Several Nigerian studies have focused on the timing and sequence of eruption of the Nigerian Dental Journal | Vol 32 No. 2 2024 than males.Out of the 424 participants, three hundred and sixty-three (363) had molar teeth available for assessment.

Table 1 : Mean age of the study participants
KEY: DS; Dental Stage; SD: standard deviation; SEM: standard error of mean; MD: mean difference Total KEY: DS; Dental Stage; SD: standard deviation; SEM: standard error of mean; MD: mean difference

Table 5 : Comparison of the mandibular permanent molars according to sex
KEY: DS; Dental Stage; SD: standard deviation; SEM: standard error of mean; MD: mean difference.

Table 7 : Comparison of the mandibular dentition anterior to the molars according to gender
DS; Dental Stage; SD: standard deviation; SEM: standard error of mean; MD: mean difference Nigerian Dental Journal | Vol 32 No. 2 2024 lateral incisor teeth were the last to emerge in that series and were noted to have

Onset of Dental Emergence Stages Among 4-15 Year-Old Nigerian Children
J Orthod Dentofacial Orthop 2000;118(04): 404-413.20.Wei Miao, Dan Zhou, Chunjie Li, Lichun Chen, Min Guan, YiranPeng, Li Mei.Dental developmental stage affects the t r e a t m e n t o u t c o m e o f m a x i l l a r y protraction in skeletal Class III children: a systematic review and meta-analysis.Aust Orthod J. 2021;37(01):37-49.21.Helm S, Seidler B. The timing of permanent tooth emergence in Danish c h i l d r e n .C o m m u n i t y D e n t .O r a l Epidemiol.1974; 2:122-129.22. M a g n u s s o n T E .E m e r g e n c e o f permanent teeth and onset of dental stages in Icelandic children.Community Dent.Oral Epidemiol.1976: 4: 30-37.