1. MECHANISM OF SECOND DENTITION

2. Diphyodont and Heterodont humans
homodont: all tooth are alike;
heterodont: teeth have diferent shapes;
poliphyodont: changing of teeth for the whole lifetime
diphyodont : 2 sets of teeth – mammals;

3. Root development - MOORREES et al.
Root completely develped
Apex open
Apex ½ closed
Apex closed
MOORREES CF, FANNING EA, HUNT EE Jr. AGE VARIATION OF FORMATION STAGES FOR TEN PERMANENT TEETH.
J Dent Res Nov-Dec; 42:

4. SECON DENTITION -MECHANISM
Mechanism – several factors responsible for normal second dentition process
Primary teeth period, after development of primary teeth – transitory period: maxillary bones are preparing for the permanent teeth arrival.

5. SECOND DENTITION Physiological developmental phenomenon;
Dynamic process: root development, periodontal development, functional occlusion.

6. SECOND DENTITION - IMPORTANCE
Normal develpment of the craniofacial complex;
Treatment planing, timing - orthodontics;
Cariology.

7. 6 years: M1 „Sechsjahrmolaren”;
First permanent molars: at the end of the line;
„Sechsjahrmolaren”;
There are no changing of teeth, so it goes often unnoticed by the parents!

8. ERUPTION - TIMETABLE PERMANENT T. Hidasi Fehér 1. Molars 6 6-7
1. incisos 8
6-8
Lateral incisor
7-9
Canine 11
9-12
1. and 2. Praemolars
9-10
10-12
2. Molar 12
11-13
3. Molar -
17-21
Upper
Eruption sequences ♂
4→5→3 ♀
3→4→5 vagy
4→3→5
Lower
Eruption sequences
♂, ♀
3→4→5

9. CHARACTERISTICE
Percentil presence of permanent teeth: prevalence of a particular tooth at a given moment in the population.
dierences between the arches;
sexual dimorfizm;
Dental age determination!;
dental status or the given age.
A FOGVÁLTÁS menete pontosabban jellemezhető paraméterekkel

10. CHARACTERISTICS
Average eruption time: the age when the percentil presence of the tooth is 50%.
IMPORTANCE:
describes the second dentition process;
comparative studies between populations;
acceleratio: comparison with older data!;
Percenti presence: tooth type 15-40%
Average eruotion time: tooth type 1-1,5 years.
A FOGVÁLTÁS menete pontosabban jellemezhető paraméterekkel

11. BONE MATURATION Second dentition is paralell with bone maturation:
Tanner-Whitehouse method TW2 (Tanner et al. 1975);
Orthodontic diagnostic value!
A FOGVÁLTÁS menete pontosabban jellemezhető paraméterekkel

12. End of secondary dentition
GROWTH- TANNER
End of secondary dentition
Chronological age

13. SECOND DENTITION CRITERIA
Presence of the permanent toothgerm
Optimal position of the toothgerm
Sufficient space
Physiological root resorption

14. PRESENCE OF THE PERMANENT TOOTH GERM
Aplasia prevalence: 3-4%;
Gábris et al.: I2˃pm2˃ PM2˃i1
Persisting primary teeth
Bolk’s terminal reduction theory

15. APLASIA: 35; 31; 41; 45. Persisting primary teeth: 75; 71; 72; 85
Bolk’s terminal reduction theory: EXEPTION
LOWER PERMANENT FIRST INCISORS

16. OPTIMAL POSITION OF THE PERMANENT TOOTHGERM
Lower incidors: lingual eruption, erupting often in the presence o the primary incisors;
Extraction of the primary teeth;
Upper canines:
Ectopia;
Retentio/Impactio

17. MESIODENS
DENS SUPERNUMERARIUS
DENS SUPPLEMENTARIUS

18. Early primary teeth extraction

19. Physiological root resorption
Genetical code!

20. PATHOLOGY TIME SPACE THE PATHOLOGICAL TRIAS:
Perturbance of the rootresoption;
Persisting primary models;
Retained permanent teeth.

21. PATHOLOGY
DENTITIO PRAECOX
DENTITIO TARDA
DENTITIO DIFFICILIS

22. INFRAOCCLUSIO SECUNDARIA
Partialis retentio; reinclusio;
Submergentia;
„Halbretention”
„submerged deciduous teeth”

23. Eruption cyst/haematoma

24. Importance of the distal plane in primary dentition