prenatal and post natal growth of craniofacial complex

prenatal and postnatal development of craniofacial complex

1. GOOD MORNING

2. PRENATAL AND POSTNATAL GROWTH OF CRANIOFACIAL COMPLEX CH.SINDHU 1 ST YR PG DEPARTMENT OF PEDIATRIC AND PREVENTIVE DENTISTRY

3. QUESTIONS 1. Explain the prenatal growth of face. 2. Describe postnatal growth of maxilla. 3. Discuss postnatal growth of mandible. 4. Explain the development of palate.

4. CONTENTS Introduction Prenatal growth and development - deveolpment of face -development of nose -development of lips -development of cheeks -development of maxilla -development of mandible -development of cranium Postnatal growth and development -development of cranium -development of maxilla - developmwnt of mandible A nomalies Conclusion References

5. DEFINITION OF GROWTH An increase in size. - Todd Growth usually refers to an increase in size and number. - Proffit Self multiplication of living substance. - J.S.Huxley Change in any morphological parameter which is measurable - Moss Quantitative aspect of biologic development per unit of time - Moyers

6. DEVELOPMENT Development is a progress towards maturity. – Todd Development connotes a maturational process involving progressive differentiation at the cellular and tissue levels. - Enlow Development refers to all naturally occurring progressive, unidirectional, sequential changes in the life of an individual from it’s existence as a single cell to it’s elaboration as a multifunctional unit terminating in death . -Moyers

7. INTRODUCTION Growth and development of an individual can be divided into pre-natal and post-natal periods.

8. PRE NATAL DEVELOPMENT The period of ovum- (from fertilization to 14 th day ) The period of embryo – ( from 14 th day to 56 th day) The period of foetus – ( from 56 th day to till birth)

9. PERIOD OF OVUM From the day of fertilization to 14 th day FERTILIZATION: Process of fusion of two haploid germ cells resulting in formation of diploid mononucleated single cell called zygote .

10. PERIOD OF OVUM

11. PERIOD OF OVUM

12. PERIOD OF EMBRYO From 14 th day to 56 th day when zygote is completely embedded in uterine wall 3 layers begin to form in embryo: 1. Ectoderm 2. Endoderm 3. mesoderm

13. PERIOD OF EMBRYO

14. PERIOD OF EMBRYO

15. PERIOD OF EMBRYO

16. PERIOD OF EMBRYO

17. PERIOD OF EMBRYO

18. Pre natal development of mandible Mandible is mixed bone ( intramembranous & endochondrial bone formation) The cartilage of 1st arch – MECKLE’S CARTILAGE At about 6th week of IUL this meckles cartilage derived from first brachial arch.

19. First structure to develop in lower jaw is mandible division of trigeminal nerve which divides into - lingual nerve(medial) - inferior alveolar nerve (lateral) Followed by mesenchymal condensation forming first brachial arch.

20. OSSIFICATION OF MANDIBLE: 1.INTRAMEMBRANEOUS OSSIFICATION: Around 6th week of ILU Intramembranous ossification mainly starts in the region of bifurcation of lingual and inferior alveolar branches and again at the point of division of inferior alveolar into incisive and mental branches, i.e., around the mental foramen area. Extension of intramembranous ossification both dorsally(posteriorly) – forms body & ramus of the mandible Ventrally(anteriorly) – till symphysis region

21. ENDOCHONDRAL BONE FORMATION: Contains 3 cartilages The condylar cartilage The coronoid cartilage The symphyseal cartilage

22. The condylar cartilage : At 5 th week of IUL -separate area of condensation just above the ventral part. At 12 th week of IUL rapidly takes shape of cone migrates inferiorly and merges with the developing ramus by about 4th month. At 20th week of IUL - This mass of cone-shaped cartilage undergoes endochondral bone formation and takes shape of the condyle.

23. The Coronoid cartilage : Appears at about 4 months of IUL (10-14 week ) Coronoid cartilage is a transient growth cartilage, becomes incorporated into the expanding intramembranous bone of the ramus and disappears long before birth. The Symphyseal cartilage : At about 7th month of IUL these undergo ossification and form mental ossicles; later, these ossicles merge in the symphysis region along with the ossification of symphysis which will be completed by the end of I st year after birth.

24. Fate of Meckel's Cartilage: A major portion of the Meckel's cartilage disappears during growth and the remnants of Meckel's cartilage gives rise to the following structures: The incus and malleus of the inner ear . The sphenomandibular ligament The lingula as bony spicule at the entrance of inferior alveolar canal Anterior ligament of malleus The mental ossicles Spine of sphenoid bone

25. CRANIOFACIAL COMPLEX The development of the skull is a blend of the morphogenesis and growth of three main skull entities arising from neural crest and paraxial mesoderm tissue. The skull entities include: 1. The Neurocranium : a) Vault of the Skull, or Calvaria: formed from intramembranous bone of paraxial mesodermal and neural crest origin; known as the Desmocranium .

26. b) Cranial base : formed from endochondral bone of neural crest origin is known as the Chondrocranium. 2 . The Face: formed from intramembranous bone of neural crest origin; also known as the Splanchnocranium or Viscerocranium .

27. PRENATAL DEVELOPMENT OF CALVARIA The mesenchyme that gives rise to the vault of the neurocranium is arranged first as a capsular membrane around the developing brain. The membrane is composed of two layers:

28. Osteogenesis of the ectomeninx occurs as intramembranous bone formation over the expanding dome of the brain, forming the skull vault or calvaria . Ectomeninx forming the floor of the brain chondrifies as the chondrocranium, which later ossifies endochondrally. The mesodermally derived ectomenix given rise to major portion of: Ethmoid (1) Sphenoid (1) Frontal(1) Parietal(2) Temporal(2) Occipital(1)

29. POST NATAL DEVELOPMENT

30. POST NATAL DEVELOPMENT OF CALVARIA At birth, the individual calvarial bones are separated by sutures & fontanelles. Sutures are joints that are peculiar to skull are immovable. At birth, flat bones are widely separated by loose connective tissue and they are called fontanelles .

31. They are 6 fontanelles : Anterior(1) Posterior(1) Posterolateral(2) Anterolateral(2)

32. Bones of cranial base

33. FLEXURE OF CRANIAL BASE: Initially cranial base grows linearly. During the embryonic and early foetal period , the linearly growing cranial base exhibits backward and downward growth to accommodate the growth of brain.

34. P OST NATAL DEVELOPMENT OF CRANIAL BASE The cranial base grows postnatally by complex interaction and combination of the following three growth processes: 1. Elongation at synchondroses 2. Extensive cortical drift and remodelling 3. Sutural growth.

35. SYNCHONDROSIS: After endochondral bone formation sutures appear in the cranial base between the ethmoid and sphenoid, and the sphenoid and occipital bones. These cartilaginous sutures are called "synchondrosis.“ The cranial base or chondrocranium acts as a junction between the cranial vault and the facial skeleton, being shared by both.

36. SYNCHONDROSIS : A) SPHENO-OCCIPITAL SYNCHONDOSIS : This is the cartilaginous junction present between the sphenoid and occipital bones. The spheno -occipital synchondrosis is active up to the age of 12-15 years.

37. B) SPHENOETHMOIDAL SYNCHONDROSIS : This is a cartilaginous band present between the sphenoid and ethmoid bone. The ossification ranges from 5 to 25 years. C) INTERSPHENOIDAL SYNCHONDROSIS : It is present in between two halves of the sphenoid bone. It disappears at birth. D) INTRASPHENOIDAL SYNCHONDROSIS : It is present in sphenoid Bone. closes between 3 to 5 years of life.

38. CORTICAL DRIFT AND REMODELING: Remodelling refers to a net result of the process where bone deposition and resorption occur so as to bring about change in size, shape and oriental relationship of the bone. Cortical drift is the direction of growth by resorption on one side and apposition on other side of the same bone. Most of the inner surface of the cranial fossa undergoes resorption and the other or below surface undergoes deposition.

39. SUTURAL GROWTH: The cranial base has a number of bones that are joined to one another by means of sutures. Some of the sutures that are present include: a. Sphenofrontal b. Frontotemporal c. Sphenoethmoidal d. Frontoethmoidal e. Frontozygomatic

40. POST NATAL DEVELOPMENT OF MAXILLA The growth of the nasomaxillary complex is produced by the following mechanisms: a. Displacement b. Growth at sutures c. Surface remodelling

41. Displacement:

42. Growth at Sutures The maxilla is connected to the cranium and cranial base by a number of sutures. These sutures include: a. Frontonasal suture b. Frontomaxillary suture c. Zygomaticotemporal suture d. Zygomaticomaxillary suture e. Pterygopalatine suture

43. Surface remodelling : Massive remodelling by bone deposition and resorption occurs to bring about: a. Increase in size b. Change in shape of bone c. Change in functional relationship

44. POST NATAL DEVELOPMENT OF MANDIBLE This is the one which undergoes the largest amount of growth postnatally. The basal bone or the body of the mandible forms the basal unit. developmentally and functionally divisible into several skeletal sub-units In the process of mandibular formation only a small amount of "endochondral bone formation“ and greater amount of "intramembranous bone formation" occur.

45. The subunits which get attached to this basal bone are At the time of birth the mandible is little more than a curved base of bone, the coronoid, angular and alveolar processes are underdeveloped.

46. The condyle The mandibular condyle has been recognized as an important growth site. The head of the condyle is covered by a thin layer of cartilage called The condylar cartilage . The presence of the condylar cartilage is an adaptation to withstand the compression that occurs at the joint. The condylar cartilage is responsible for the condylar growth thereby increasing mandibular length.

47. The head of the condyle grows in posterior direction with proliferation of cartilage and its subsequent replacement by endochondral ossification. The condyle grows upwards and back-wards resulting in downwards and forward translocation of the Mandible. Simultaneously selective remodelling of the condyle follows Enlow's 'V' principle to achieve typical shape of the condyle. The condylar growth reaches peak at pubertal growth spurt (12-15 years) and ceases by 20 years of age.

48. Ramus The ramus moves progressively in posterior direction by a resorption (at the anterior border) and deposition (at the posterior border) with this the ramus drifts posteriorly. The mandible translates anteriorly.

49. Corpus or the body of mandible The corpus or body of the mandible is formed at the expense of ramus repositioning in posterior direction. The resorption occurs at the anterior end and deposition at the posterior end of ramus.

50. The coronoid process It has a propeller-like twist mechanism of growth. It increases in height (superiorly), widens (laterally) and at the same time grows posteriorly.

51. Angle of the mandible The region of the angle of the mandible is augmented by deposition in the posterior border of the ramus. On the buccal side, resorption occurs on the anterosuperior portion while deposition takes place on the postero -inferior part. On the lingual side of the angle of mandible, resorption takes place on the postero -inferior aspect while deposition occurs on the antero-superior aspect.

52. Alveolar process & chin Alveolar process develops in response to the presence of tooth buds. The alveolar process grows upwards by the apposition (deposition) of bone on its occlusal border in response to the tooth buds.

53. The chin The chin is a specific human characteristic and is found in its fully developed form in recent man only. It is poorly developed in the infancy period. Gradually, deposition (apposition) occurs in the anterior inferior most part of the mandible and accelerates during pubertal growth to attain chin prominence.

54. ANOMALIES

55.  There are multiple genetic and environmental factors which contribute to craniofacial development. Within craniofacial disorders and  abnormalities , orofacial clefts, and specifically  cleft lip (CL) and  cleft palate (CP) are the most common in humans.  Occurrences of CL/P are most often isolated and nonsyndromic conditions.  Around thirty percent occur with other structural variances, and over 500 syndromes have been identified in which clefting is a principal feature.

56. FACTORS Radiation , Maternal infection, Drugs / chemicals, Chromosomal abnormalities or mutations , Maternal smoking or drinking alcohol, Failures or deviation in neural crest cell migrations,

57. • Harelip : Unilateral harelip : failure of fusion of maxillary process with medial nasal process on one side Bilateral harelip : failure of fusion of both maxillary processes with the medial nasal process Midline cleft of upper lip : Defective development of the lowermost part of the frontonasal process may give rise to a midline defect of the upper lip

58. VEAU’S CLASSIFICATION OF CLEFT LIP Class I- unilateral notching of vermilion Class II- cleft lip but nasal floor is spared Class III- Cleft involving nasal floor Class IV- Bilateral cleft

59. Oblique facial cleft : Nonfusion of the maxillary and lateral nasal process gives rise to a cleft running from the medial angle of the eye to the mouth . The nasolacrimal duct is not formed.

60. Tessier classification  Midline clefts - 0,14 Paramedian clefts – 1,2,12,13 Orbital clefts – 3,4,5,9,10,11 lateral clefts – 6,7,8 Tessier P .Anatomical classification of facial, craniofacial and latero-facial clefts, Journal of Maxillofacial Surgery,1976,vol 4,69-92.

61. Macrostomia Inadequate fusion of the mandibular and maxillary processes with each other may lead to an abnormally wide mouth Microstomia Too much fusion may result in a small mouth

62. Proboscis Very rarely the nose forms a cylindrical projection, or proboscis jutting out from just below the forehead. This anomaly may sometimes affect only one half of the nose and is usually associated with fusion of the two eyes ( cyclops ).

63. Mandibulofacial dysostosis, Treacher Collins syndrome or first arch syndrome : The entire first arch may remain underdeveloped on one or both sides, affecting the lower eyelid (coloboma type defect), the maxilla, the mandible, and the external ear. The prominence of the cheek is absent and the ear may be displaced ventrally and caudally. There may be presence of cleft palate and of faulty dentition. One half of the face may be under developed or overdeveloped.

64. Crouzon syndrome ▪ Due to premature closure of sutures ▪ Protruberance Of Frontal Region. ▪ Hypoplasia Of Maxilla With Mandibular Prognathism. ▪ Short Upper Lip & Nose Resembles Parrot Beak. ▪ Protruded eyes due to early closure of superior sutures of maxilla

65. Pierre robin syndrome ▪ Severe mandibular hypoplasia ▪ U- shaped cleft palate Under developed mandible catch-up the normal growth

66. CRANIOFACIAL CLEFTS ASSOCIATED SYNDROMES Apert syndrome Treachercollins syndrome Crouzon syndrome Goldenhar syndrome Van Der Woude Syndrome Pierre Robin Syndrome

67. Syndromes Associated With Midfacial Deficiency Apert Syndrome Crouzon Syndrome Cleidocranial Dysplasia Marfan Syndrome Treacher Collins Syndrome Hemifacial Microsomia (Goldenhar Syndrome) Gorlin Syndrome  

68. Hypertelorism The eyes may be widely separated ( hypertelorism ). The nasal bridge is broad. This condition results from the presence of excessive tissue in the frontonasal process .

69. Cleft palate Defective fusion of the various components of the palate gives rise to clefts in the palate. These vary considerably in degree. Complete cleft palate: • Bilateral complete cleft : Failure of fusion of both palatine processes of maxilla with premaxilla. A y-shaped cleft will be present between primary and secondary palate and between the two halves of secondary palate. It presents bilateral cleft of upper lip also

70. • Unilateral complete cleft : Nonfusion of one side palatine process of maxilla with premaxilla. It presents unilateral cleft of upper lip.

71. Incomplete cleft palate : Cleft of hard and soft palate Cleft of soft palate Bifid uvula

72. VEAU CLASSIFICATION (1931) Class I- incomplete cleft involving soft palate only Class II- Cleft involving the hard palate and soft palate Class III- Complete unilateral cleft, involving the lip and palate. Class IV- Complete bilateral cleft.

73. Epstein’s pearls These are keratin filled yellow-white epithelial nodules found along the midpalatine raphe. Derived from entrapped epithelial remnants along the line of fusion.

74. CONCLUSION Complete knowledge about embryology will helps you to assesses the pre natal condition of life . Having clear idea about growth & development will helps to identify the abnormalities or any malocclusion at early stages as we are dealing with preventive dentistry which may reduce the severity of the condition & improves prognosis.

75. REFERENCES Text book of orthodontics -6th edition- S.I BHALAJHI Textbook of orthodontics – 2nd edition – S Gowri Sankar Human embryology – I B Singh Textbook of pedodontics-5 th edition-Nikhil marwah