enlow counterpart principle with reference articles

enlows counterpart principle pg level has articles included

1. JOURNAL OF AMERICAN DENTAL ASSOCIATION,1971

2. The multiple growth processes in all the various parts of the face and cranium are described separately as individual " regions " or " stages ”. The face of each of us is the aggregate sum of all the many balanced and imbalanced craniofacial parts combined into a composite whole. Balanced growth is the Facial and cranial enlargement, in which form and proportions remain constant. Imbalance growth is when changes in facial shape and form occur.

3. Imbalances are produced by differences in respective amounts or directions of growth. A perfectly balanced mode of growth in all the parts of the face and cranium never occurs in real life. Making everything actually fit requires certain normal "imbalances .“ The process of compensation is a feature of the developmental process in order to offset the effects of disproportions in other regions

4. Regional imbalances often tend to compensate for one another to provide functional equilibrium. This is the COUNTERPART PRINCIPLE OF CRANIOFACIAL GROWTH . It states, simply, that the growth of any given facial or cranial part relates specifically to other structural and geometric "counterparts" in the face and cranium .

5. TRIPOD ANALOGY

6. DYNAMICS OF MORPHOGENESIS AS VISULAISED IN HEADFILMS

7. Two reference lines one vertical and other horizontal are used so that amount and direction of growth changes can be visualized The molars are in class I relation

8. STAGE 1 Bony maxillary arch lengthens in posterior direction The overall length of maxillary arch has increased by the same amount that the P tm moves posteriorly

9. STAGE 2:MAXILLARY DISPLACEMENT As the maxillary tuberosity grows and lengthens posteriorly, the whole maxilla is simultaneously carried anteriorly

10. STAGE 3:MANDIBULAR CORPUS LENGTHENING Mandibular corpus lengthens to match the elongation of maxilla It does so by remodeling conversion from ramus

11. STAGE 4:MANDIBULAR RAMUS REMODELING The condyle and the posterior part of ramus remodel posteriorly This returns the horizontal dimension of the ramus to the same breadth

12. STAGE 5:MANDIBULAR DISPLACEMENT The whole mandible, now, is displaced anteriorly by the same amount that the ramus has relocated posteriorly . This is the primary type of displacement because it occurs in conjunction with the bone's own enlargement.

13. NOTE: The corpus of the mandible elongates primarily in a posterior direction , just as the maxilla also lengthens posteriorly The whole ramus has moved posteriorly. However, the only actual change in horizontal dimension involves the mandibular corpus, which becomes longer. The horizontal dimension of the ramus remains constant The anterior displacement of the whole mandible equals the amount of anterior maxillary displacement assuming everything is perfectly balanced. the class I position of the teeth has been returned

14. 4. obliquely upward and backward direction of ramus remodeling must also lengthen its vertical dimension.This separates the occlusion because the mandibular arch is displaced inferiorly as well as anteriorly. 5. In both the maxilla and mandible, the type of displacement is primary Increment of backward growth at maxillary tuberosity(stage 1) Amount of forward displacement of maxilla(stage 2) Amount of corpus lengthening (stage 3) Growth of posterior part of ramus (stage 4) Mandibular displacement (stage 5)

15. STAGE 6:MIDDLE CRANIAL FOSSA GROWTH Increase in dimension of temporal lobes of the cerebrum and the middle cranial fossa. Resorption on the endocranial side and deposition of bone on the ectocranial side of the cranial floor . The spheno -occipital synchondrosis provides endochondral bone growth in the midline part of the cranial floor. Growth expansion of middle fossa now projects it anteriorly beyond the vertical reference line

16. STAGE 7:SECONDARY DISPLACEMENT OF NASOMAXILLARY COMPLEX As the middle cranial fossa expands they cause the secondary displacement of the nasomaxillary complex. The nasomaxillary complex, is suspended by sutures from the anterior cranial fossae and frontal lobes

17. STAGE 8:SECONDARY DISPLACEMENT MANDIBLE The expansion of the middle cranial fossa , also has a displacement effect on the mandible SECONDARY DISPLACEMENT

18. The extent of maxillary protrusive displacement far exceeds the amount of mandibular protrusive displacement Because The spheno -occipital synchondrosis lies between the condyle and the anterior boundary of the middle cranial fossa . The result is an offset horizontal placement between the upper and lower arches. The upper incisors show an " overjet ," and the molars are in a Class II position

19. STAGE 9:COUNTERPARTS:MCF-RAMUS The horizontal growth of the ramus places the mandibular arch in a more forward position. What the middle cranial fossa does for the maxillary body, in effect, the ramus does for the mandibular body.

20. The horizontal (not oblique) dimension of the ramus now equals the horizontal (not oblique) dimension of the middle cranial fossa.

21. Both ramus and middle cranial fossa are counterparts of the pharyngeal space. The skeletal function of the ramus is to bridge the pharyngeal space and the span of the middle cranial fossa in order to place the mandibular arch in proper anatomic position with the maxilla . The anteroposterior breadth of the ramus is critical. if it is too narrow or too wide the ramus places the lower arch too retrusively or too protrusively respectively

22. STAGE 10:MAINTAINING VERTICAL BALANCE The entire mandible is displaced anteriorly at the same time that it remodels posteriorly. Condyle projects upward and backward. As a result, mandible displaces in downward as well as forward direction.

23. The total extent of this vertical growth must match the total vertical lengthening of the nasomaxillary complex and the upward eruption and drift of the mandibular dentoalveolar arch . The protrusion of the maxilla during Stage 7 ( i.e.secondary displacement of nasomaxillary complex)has now been matched by an equivalent amount of mandibular protrusion. The molars have once again been "returned" to Class I positions, and the upper incisor has no overjet .

24. STAGE 11 Growth of the floor of the anterior cranial fossa and the forehead occurs Deposition on the ectocranial side with resorption from the endocranial side. The nasal bones are displaced anteriorly.

25. The upper part of the face, which is the ethmomaxillary (nasal ) region , also undergoes equivalent growth increments . This facial area increases horizontally to an extent that matches the expansion of the anterior cranial fossa above and palate below it. These areas are all counterparts to one another. The growth process involves direct bone deposition on the forward-facing cortical surfaces of the ethmoid , the frontal process of the maxilla, and the nasal bones. Most of the internal bony surfaces of the nasal chambers are resorptive . anterior displacement takes place in conjunction with growth at the various maxillary and ethmoidal sutures.

26. STAGE 12 The vertical lengthening of the nasomaxillary complex ,occurs by: Resorption on the superior (nasal) side of the palate. Deposition on the inferior (oral) side. Produces a downward remodeling movement of the whole palate from 1 to 2 .

27. STAGE 13:VERTICAL DRIFT Vertical growth by displacement is associated with bone deposition at the many and various sutures of the maxilla where it contacts the multiple , separate bones above and behind it Bone is added at these sutures by amounts equalling whole maxillary displacement inferiorly

28. downward movement of the palate and maxillary arch occurs by: Part 1 to 2 – by remodelling and each tooth’s own movement due to remodelling on lining surface in each socket. THIS IS VERTICAL DRIFT OF TOOTH Part 2 to 3 – by sutural growth and primary displacement and passive downward displacement of whole maxillary dentition.

29. STAGE 14:MANDIBULAR ALVEOLAR DRIFT The mandibular teeth and alveolar bone drift upward to attain full occlusion. This is produced by a superior drift of each mandibular tooth, together with a corresponding remodeling increase in the height of the alveolar bone.

30. the extent of downward drift of the maxillary teeth exceed the extent of upward drift by the mandibular teeth. Much less growth is thus available to "work with" in major orthodontic movements of the mandibular teeth , as compared with the maxillary teeth. However, there is a significant extent of vertical drift by the mandibular anterior teeth if a curve of Spee exists.

31. STAGE 15:ANTERIOR DENTAL CHANGES Remodeling changes occur in the incisor alveolar region, the chin, and the corpus of the mandible along with posterior region(stage 14). The lower incisors undergo a lingual tipping so that the uppers overlap the lowers for proper overbite.

32. STAGE 16:ZYGOMA Remodelling of the forward part of the zygoma and the malar region of the maxilla occurs in this stage Just as the maxilla lengthens horizontally by posterior remodeling growth, the malar area also remodels posteriorly. Continued deposition of new bone on its posterior side and resorption from its anterior side occurs

33. The amount of deposition on the posterior side, however, exceeds resorption on the anterior surface, so that the whole malar protuberance becomes larger. The zygomatic process remodels posteriorly by anterior resorption and posterior deposition. Just as the coronoid process relocates backward by anterior resorption and posterior deposition to keep pace with the overall posterior elongation of the whole bone.

34. STAGE 17 The malar area is moved anteriorly and inferiorly by primary displacement as it enlarges. The cheekbone thereby proportionately matches the maxilla in (1) the directions and amount of horizontal and vertical remodeling relocation (2) the directions and amount of primary displacement.

35. This is a simplified , schematic representation used to describe various dimensional and alignment combinations involved in craniofacial construction and growth .

36. MORPHOGENETIC BASIS FOR CRANIOFACIAL VARIATIONS

37. ANATOMICAL EXPRESSIONS OF BONY DIMENSIONS three important, primary factors are involved in the structural expression of the various dimensions of any given bone. They are: its effective dimension ; its overall size; its alignment

38. The structurally effective dimension of a bone or part of a bone must be differentiated from its total length . For example, in relating the bony maxillary arch to its counterpart, the bony mandibular arch, the protrusion of the chin is not related to the fit of one arch to the other. The configuration of the chin can have significance in its own right, but its role as a part of the composite assembly pattern is secondary . The overall size of a bone is of course an obvious basic factor in the expression of that bone’s particular dimensions.

39. 3. The third factor is the alignment of the whole bone or the structurally effective parts of that bone for example, an alignment (rotation) of segment Co-SE is changed

40. CRANIOFACIAL VARIATIONS . If the bony maxilla is horizontally long relative to the mandibular corpus (or the corpus is short), a retrognathic profile pattern results. A Class I molar relationship can occur, however, if no other skeletal or dental dysplasia exists, since the posterior parts of the bony maxillary and mandibular arches are not offset. The ramus and the cranial floor are balanced

41. 2. If the upper part of the nasomaxillary complex becomes horizontally long relative to the anterior cranial floor, a large frontal sinus, sloping forehead, high nasal bridge may result. The orbits may also appear recessed. The profile can appear somewhat retrognathic because of the upper maxillary protrusion, although no malocclusion need be present.

42. 3 .If the Co-SE segment is horizontally long relative to its anatomic equivalent the ramus, the entire maxillary complex is in an offset, anteriorly (and also superiorly ) A retrognathic pattern results, and a Class II molar relationship can occur even though the actual dimension of the maxilla equals that of the corpus . If the bony maxillary arch is also long relative to the corpus, aggravation of the Class II situation is seen

43. 4. If the posterior part of the nasomaxilla is vertically long the alignment of the ramus adjusts to its vertical length the ramus rotates downward and backward, thereby increasing the expression of its vertical dimension. the horizontal length of the ramus is necessarily decreased A retrognathic profile is produced and a class II molar relationship occurs

44. the functional occlusal plane has rotated downward . Unless the vertical dimension in the anterior part of the maxillary complex becomes correspondingly lengthened, an anterior open bite results. Or, as the ramus rotates downward at the condylar pivot, the ramus-to-corpus angle may change during growth so that the corpus rotates upward at the gonial pivot to sustain occlusal contact . The mandibular posterior molars, further, may become intruded and the anterior teeth extruded at the same time.

45. INTRINSIC ADAPTATIONS AND COMPENSATIONS

46. If the mandibular corpus is long with respect to the bony maxillary arch , any of several compensatory adjustments can still produce a good facial profile A horizontally long cranial floor, A horizontally short ramus. the PM vertical dimension may also be long relative to the cranial floor-ramus composite dimension

47. a more anterior and inferior alignment of the posterior part of the cranial floor. It produces an inferior and posterior rotation of the ramus at the condylar pivot

48. . To obviate an anterior open bite resulting from downward ramus rotation, the anterior maxilla height increases proportionately . Alignment of the occlusal plane occurs by alveolar growth , a decrease in the gonial angle , an intrusion of the mandibular molars and an increase in the depth of the overbite . Such a resulting aggregate combination might comprise a corpus with a Class III actual length, a Class II maxillary and cranial floor position, a Class II molar relationship, and a Class I profile.

49. If the horizontal dimension of the bony maxillary arch is long relative to the corpus , an increase in the anterior vertical height of the nasomaxilla The gonial angle may be more obtuse

50. A horizontally long bony maxillary arch may also be compensated for by . vertically short PM dimension that allows an upward and forward rotation of the ramus at the condylar pivot; by a vertically high cranial floor-ramus composite; or by a posterior and superior rotational alignment of the posterior portion of the cranial floor

51. CONCLUSION The final result of all the regional changes is a craniofacial composite that has essentially the same form and pattern present when the first stage began . Only the overall size has been altered. All the growth changes among the specific parts and counterparts have been purposefully balanced to give an understanding of the term ' 'balanced growth".

52. It represents the results of the overall process of facial enlargement. This overlay does not, however, represent the actual growth processes themselves that is, the changes produced by remodeling, Relocation and displacement. It shows the cumulative summation of all four processes and demonstrates the locations of all the regional parts, before and after.

53. 1971, Angle Orthodontics Aim- To examine the role and the incidence of these intrinsic compensating factors and to relate them to the different major categories of craniofacial patterns.

54. While comparing anatomical part directly with its particular architectural, developmental counterpart , two factors are considered:- 1. Alignment (rotational position) of the parts relative to each other. 2. The anatomical effect of the sizes ( vertical and horizontal) of the parts relative to each other. This means that any upwards, downwards rotation will directly effect the horizontal or vertical position of each part. The various cranial and facial regions were to found to contribute in an aggregate manner to the establishment of a composite basis for over-all maxillary or mandibular protrusive patterns.

55. Thus , a number of separate but interrelated, regional, c ause-and-effect factors tend to augment each other in a cumulative, composite manner. The Class I individuals, however, are characterized by an effective balance between variable numbers of offsetting (compensating) maxillary and mandibular protrusive effects among the various regional counterpart relationships . Class II and III individuals may also show a degree of such intrinsic compensation but the severity of their over-all skeletal dysplasia is determined by the distribution and the extent of cumulative, protrusive effects in conjunction with the extent of some other effects that provide a greater or lesser degree of intrinsic offset.

56. Two basic types of Class I and Class II patterns exist . If A point lies anterior to B point with respect to the functional occlusal plane, the craniofacial pattern is designated as a Class I A or a Class II A type. If B point lies anterior to A point with respect to the functional occlusal plane, however, the craniofacial pattern is designated as a Class I B or a Class II B type. Class IA group having a Class II (maxillary protrusion) tendency while Class IIA tends to have a more severe type of skeletal discrepancy. Class IIB have a much lesser incidence of severe skeletal discrepancy due to greater number of compensating Class III anatomical effects.

57. Synergic and Reciprocal Relationships If the effects between any two groups of parts and counterparts are reciprocal (i.e., one has a maxillary protrusive effect while the other has a mandibular protrusive effect ), the composite anatomical result is thereby partly or wholly offsetting and compensatory. If the two different part-counterpart groups have a common protrusive effect, this relationship is synergic and their respective effects are cumulative within that individual. Such synergic relationships may be either advantageous or disadvantageous in a given person.

58. Regional relationships that produce a cumulative, synergic maxillary protrusion effect in a Class II individual augment and worsen the over-all extent of his composite maxillary prognathism. While regional relationships having synergic mandibular protrusive effects in a Class II individual are advantageous because they contribute a degree of regional compensation within the craniofacial framework and thereby reduce the aggregate extent of maxillary protrusion.

59. CORPUS-OCCLUSAL COMPENSATORY RELATIONSHIP Three essentially different rotational sites are incorporated within the mandible as a whole: The ramus, which can rotate upward and forward or downward and backward The corpus, which can rotate either upward or downward (opening and closing the ramus-to-corpus angular junction) T he dental arch, which can undergo an independent upward or a downward rotation by an extrusion or intrusion of the anterior or posterior teeth.

60. The rotational status of the ramus , using the condyle as a pivot, is directly dependent in a cause-and-effect relationship with the long or short nature of the relative PM ( midface) vertical dimension. A “short” midface relative vertical length is associated with a consequent, more forward and upward ramus alignment. A “long” midface relative vertical length (and often a forward and downward rotation of PCF as well) , conversely , is related to a more backward and downward alignment of the ramus.

61. Two basic compensatory responses or, frequently, a combination of both can occur to maintain full length closed occlusion. The maxillary teeth can extrude and descend for a progressively increasing vertical distance front the posterior to the anterior ends of the arch. The posterior-most maxillary tooth remains in the same vertical position, but each succeeding tooth moves inferiorly for a greater distance until full-length occlusal contacts are made.

62. Second, t he mandibular teeth can become extruded to a progressively increasing extent from the posterior to anterior ends of the arch until contact is made with each corresponding maxillary tooth. A vertically “long” alveolar region characterizes such individuals in the anterior portion of the mandibular corpus due to the upward direction of incisor positioning.

63. However, a progressive extrusion of the corresponding anterior mandibular teeth completes closure of the intervening distance to provide full-length occlusal contact . The result is a distinctive c urved contact line from the posterior molars to the incisors. The middle span of the maxillary teeth descends, as in the first type of adaptive response described above, but the progressively increasing extent of extrusion required for each subsequent tooth in the more anterior part of the maxillary arch falls short.

64. However, the maxillary teeth do not fully descend in a progressively increasing manner from back to front into occlusal contact, although a partial descent in a curved line often occurs as noted above.

65. 2023, Diagnostics

66. AIM T he aim of this study is to provide a method to perform the analysis of Enlow’s neutral track in 3D.( As enlow 3d analysis composed of all horizontal , vertical and neutral counterpart)

67. MATERIAL AND METHOD 18 CBCT images of skeletal class I subjects (12male and 6 female) were taken. For each subject, 2D Enlow’s neutral track analysis was performed on lateral cephalograms extracted from CBCT images using the OrisCeph3 software and 3D neutral track analysis was performed on CBCT images using the Materialise Mimics Software.

68. N eutral track analysis allows us to evaluate the “rotational factor” in the craniofacial development and growth of the following structures: the middle cranial floor, mandibular ramus, occlusal plane and nasomaxillary complex. 2D ANALYSIS compares individual track with neutral track .

69. The angle between MCFn and PMn plane remains same 40.3° as in individual track

70. 3D ANALYSIS The same 3 individual track planes (MCF,PM and MR ) were identified but with different landmarks than the 2D ones.

71. So to compare both 2D and 3D analysis we used following angles: MCF-PM and MCF-RM

72. RESULT The gap between the values of each variable was small and no statistically significant difference was highlighted by the paired Student’s t-test (p > 0.05), confirming the null hypothesis and suggesting that the proposed 3D analysis method is reliable for evaluating certain cephalometric angles.

73. CONCLUSION This is the first study to propose a method as to how to perform the neutral track analysis in 3D and is also the first study proposing a method to analyze the rotational factor of the craniofacial structures on CBCT. This method can further be used in orthodontic diagnostic phase and in orthognathic surgery planning.

74. As the ramus rotates downward and backward, the corpus is necessarily also carried downward with or without any increase or opening of the gonial angle. A downward-aligned corpus is thereby produced, but the direct cause is a rotation of the ramus at the condyle and not a rotation of the corpus. I n some individuals, the corpus itself can become rotated inferiorly, independently of the ramus. The mandibular occlusion , in either case, is also carried into such a downward-aligned position by the ramus and/or corpus rotation. If no corresponding occlusal rotational adjustments occur, it is apparent that open bite situation is created.

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