ENLOW’S ‘V’ & COUNTERPART PRINCIPLE by Dr. Sourabh Dutta.pptx

Two theories of Growth: ENLOW’S ‘V’ PRINCIPLE AND ENLOW COUNTERPART

1. CONTENTS: INTRODU CTION DISPLACEMENT REMODELLING ENLOW’S ‘V’ PRINCIPLE ENLOW’S COUNTERPART PRINCIPLE CONCLUSION VON LIMBORGH’S THEORY Presented by, Dr. SOURABH DUTTA

2. INTRODUCTION Growth is the quantitative aspect of biologic development and is measured in units of increase per units of time, for instance, inches per year or grams per day. -MOYERS Entire series of sequential anatomic and physiological changes taking place from the beginning of prenatal life to senility. -MEREDITH

3. DISPLACEMENT It is described as the change in the position of an object following the application of force. Displacement of bones occurs with growth in two ways: Primary Displacement of bone occurs due to its growth, which causes it to move from its original position. For example displacement of chin anteriorly due to the increasing mandibular length. Secondary displacement is an illustration of growth at a location subsequent to actual growth occurring in a distant part of skeletal system.

4. REMODELLING Remodelling is a process of progressive adjustment of bones to maintain their shape, proportions and size. Remodelling of bone occurs at different sites concurrently with increase in bone size. TYPES: Surface remodelling occurs on the surface of bones and leads to changes in topography. Structural remodelling causes a change in the inherent architecture of the bone and may lead to change in the density and mechanical properties of the bone.

5. ENLOW’S ‘V’ PRINCIPLE Enlow’s ‘v’ principle was given in 1982 by DONALD H. ENLOW. It is the most useful and basic concept of facial growth. According to the ‘ V’ principle, bone deposition occurs on inner side of ‘V’ while resorption takes place on the outside surface which leads to widening of the ‘ V’ configuration ; at the same time the structure translates from its original position and move towards the wide end of the V.

6. The ‘V’ principle is an important facial skeletal growth mechanism, since many facial and cranial bones have ‘V’ configuration or ‘ V’ shaped regions. Thus an increase in size and growth movement takes place in a unified process . Hence it is also called as expanding ‘V’ principle.

7. 1. PALATAL REMODELLING: G rowth of hard palate in the coronal section shows resorption occurs on the outer(nasal)surface and deposition on the inner(palatal)surface. Progressive remodelling, along with the growth at the mid palatal suture, and the secondary displacement due to growth of nasal bones, increases the width of the palate and causes it to descend vertically downwards.

8. 2. RAMUS TO CORPUS REMODELLING: Growth of mandible also occurs in concordance with the ‘V’ principle. When viewed from above, the condyle and ramus expand in a posterior and lateral direction due to growth in the body, ramus and the condyle itself. With growth there is progressive relocation of the entire ramus in a posterior direction. Resorption occurs on the anterior edge with resultant lingual shift of the anterior part of the ramus to become added to the corpus.

9. ENLOW’S COUNTERPART PRINCIPLE OF GROWTH. It states that growth of any given facial or cranial part relates specifically to other structural and geometric counterparts in relation to it. There are many structures in craniofacial skeleton that can be constructed as counter parts. They are: The nasomaxillary complex and the anterior cranial fossa. The middle cranial fossa and the width of ramus. Maxillay tuberosity and lingual tuberosity.

10. To illustrate the counterpart principle, a tripod is used as an analogy. The tripod has a series of telescoping segments in each leg; the length of each segment matches the length of its counterpart segments in the other two legs. If all the segments are extended to exactly the same length, the tripod retains geometric balance and overall symmetry.

11. If however, any one segment is not extended equal to others, the leg as a whole is either shorter or longer, although the remainder of all segments in that leg match their respective counterparts. One can thus identify which particular segment is different and determine the extent of imbalance. Fig1: all the segments ane equal to their respective counterparts. Fig2: segment X is shorter in respect to Y so there is retrusion of segment Z. Fig3: segment a, b, c are shorter in respect to there segment counterparts in other legs. All theses regional imbalances offset one another, so the total length of each leg is same.

12. STAGE 1: The overall length of the maxillary arch has increased by the same amount that PTM moves posteriorly. Bone has been deposited on the posterior-facing cortical surface of maxillary tuberosity. Resorption occurs on the opposite side of same cortical plate, which is the inside surface of maxilla within the maxillary sinus

13. STAGE 2: Involves displacement, as the maxillary tuberosity grows and lengthens posteriorly, the whole maxilla is simultaneously carried anteriorly. A protrusion of the forward part of the arch now occurs, not because of the direct growth in the forward part itself, but rather because of the growth of the posterior region of the maxilla as a whole bone is simultaneously displaced anteriorly.

14. STAGE 3: The mandibular corpus(body) lengthens to match the elongation of maxilla. The anterior part of ramus remodels posteriorly, a relocation process that produces corresponding elongation of corpus. A class 2 type of r elationship still exists between the maxillary and mandibular molars.

15. STAGE 4: The whole mandible is displaced anteriorly, just as the maxilla becomes carried anteriorly, while it simultaneously grows posteriorly. To do this, the condyle and the posterior part of ramus remodel posteriorly.

16. STAGE 5: The corpus of the mandible elongates primarily in posterior direction, just as the maxilla also lengthens posteriorly. The whole ramus has moved posteriorly. The only actual change in horizontal dimension involves the mandibular corpus, which becomes longer. The anterior displacement of the whole mandible equals the amount of anterior maxillary displacement. The position of maxilla and mandible are now in balance and class-I position of teeth has been returned.

17. STAGE 6: The dimensions of the temporal lobes of the cerebrum and middle cranial fossa have also been increasing at the same time. This is done by resorption on the endocranial side and deposition of bone on the ectocranial side of the cranial floor.

18. STAGE 7: The maxillary tuberosity remains in constant position on the vertical reference line as this interface line moves forward. The forehead, anterior cranial fossa, cheekbone, palate and maxillary arch all undergo protrusive displacement in an anterior direction. This is called secondary displacement.

19. The floor of the middle cranial fossa is carried forward as the temporal and frontal lobes of the cerebrum growth increases. The nasomaxillary complex, suspended by sutures from anterior cranial fossa and frontal lobes, is thus carried anteriorly as the combined frontal and temporal lobes progressively expand.

20. STAGE 8: The expansion of the middle cranial fossa also has the effect on the mandible. This too is secondary type of displacement. The extent of displacement effect , is much less than that of maxilla. The upper incisors show overjet and the molars are in class- ll position.

21. STAGE 9: The horizontal extent of the middle cranial fossa elongation is matched by the corresponding extent of horizontal increase by ramus. The horizontal dimensions of ramus equals horizontal dimensions of middle cranial fossa.

22. STAGE 10: The oblique manner of condyle growth necessarily produces an upward and backward projection of condyle with a corresponding downward and forward direction of the mandibular displacement. This results in further descend of mandibular arch and separation of occlusion. The total extend of the vertical growth must match the total vertical lengthening of nasomaxillary complex. The molars have once again returned to Class-I position and the upper incisors have no overjet.

23. STAGE 11: Nasal bones are displaced anteriorly. The posterior-anterior length of anterior cranial fossa is now in balance with the extent of horizontal lengthening of the structural counterpart, the maxillary arch.

24. STAGE 12: The vertical lengthening of nasomaxillary complex, as with the horizontal elongation is brought about by: Primary displacement movement Growth by deposition and resorption. The combination of resorption on the superior side of palate and deposition on the inferior side produces downward remodelling movement of whole palate.

25. STAGE 13: Maxilla is carried inferiorly by physical growth forces of enclosing soft tissues. This is accompanied by bone deposition in sutures responding to mutual g rowth signals relating to both displacement and remodelling. The increment of bone growth in suture exactly equals the amount of inferior displacement of whole maxilla. This is the primary displacement. Vertical drift of the tooth occurs i.e., the movement of the tooth by its own movement as bone is added and resorbed on appropriate linning surfaces in each socket.

26. STAGE 14: The maxillary arch has grown downwards. Now the mandibular teeth and alveolar bone drift upward to attain full occlusion. This is produced by superior drift of mandibular tooth, together with the remodelling increase i n the height of alveolar bone. The extend of this upward movement plus that of the downward growth movement by maxillary arch equals the combined extent of vertical remodelling by the ramus and middle cranial fossa.

27. STAGE 15 : The remodelling changes also occur in the incisor alveolar region, the chin and the corpus of the mandible. Lower incisors undergo lingual tipping for proper overbite. The movement of teeth is accompanied by resorption on the labial surface of the alveolar region just above the chin and deposition on the lingual side. Bone is progressively added to the external surface of chin itself as well as the underside and other external surfaces of corpus.

28. STAGE 16: The forward part of zygoma and malar region of maxilla remodel. The malar area remodels posteriorly by deposition on posterior side and resorption on the anterior side. The front surface of whole cheek bone is thus resorptive. The amount of deposition on posterior side, exceeds resorption on anterior surface so that the whole malar prominance is larger.

29. STAGE 17: The malar area is moved anteriorly and inferiorly by primary displacement as it enlarges. The cheek bone thus proportionately matches the maxilla in… The directions and amount of horizontal and vertical remodeling relocation. The directions and amount of primary displacement.

30. CONCLUSION The final result is a craniofacial composite that has essentially the same form and pattern when the first stage was begun. Only the overall size has been altered. All the growth changes among the specific parts and counterparts has been purposefully balanced to give an understanding of the meaning of ‘balanced growth’ .

31. VON LIMBORGH’S THEORY Von Limborgh in 1970 This theory is conceptual, taking only the positive aspects of Scott’s cartilaginous theory, sutural dominance theory by Sicher and Moss, Functional matrix theory. He suggested 6 factors that controls growth. Van Limborgh lists the essentials of all three hypothesis.

32. 6 factors that control growth Growth of synchondrosis and endochondrial growth is exclusively under the control of intrinsic growth factors. The intrinsic factors controlling Intramembraneous growth i.e., growth at sutures, periosteum growth to a larger extend are general in nature. Cartilaginous parts of the skull must be considered as growth centres.

33. Sutural growth is controlled by both cartilaginous growth and growth of adjacent structures in the head. Periosteal growth to a large extend depends on growth of adjacent structures. Intramembraneous bone formation is additionally influenced by local non- genetic environmental factors inclusive of muscle forces.

34. REFERENCES: CONTEMPORARY ORTHODONTICS ----BY WILLIAM R. PROFFIT. BOOK OF ORTHODONTICS ---- BY OM PRAKASH KHARBANDA. ESSENTIALS OF FACIAL GROWTH ---- BY ENLOW AND HANS.