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Contemporary Orthodontics (sixth edition) Annotations

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Contemporary Orthodontics (sixth edition) Annotations

Contemporary Orthodontics (sixth edition) TOC

1 Malocclusion and Dentofacial Deformity in Contemporary Society

The Changing Goals of Orthodontic Treatment > The Development of Orthodontics

  • p. 12: Annotation
  • p. 12: Annotation
  • p. 12: Edward H. Angle (
  • p. 12: dentition.
  • p. 12: Angle’s postulate was that the upper first molars were the key to occlusion and that the upper and lower molars should be related so that the mesiobuccal cusp of the upper molar occludes in the buccal groove of the lower molar. If the teeth were arranged on a smoothly curving line of occlusion (Fig. 1.2) and this molar relationship existed (Fig. 1.3), then normal occlusion would result.
  • p. 12: Angle then described three classes of malocclusion, based on the occlusal relationships of the first molars: • Class I: Normal relationship of the molars, but line of occlusion incorrect because of malposed teeth, rotations, or other causes • Class II: Lower molar distally positioned relative to upper molar, line of occlusion not specified • Class III: Lower molar mesially positioned relative to upper molar, line of occlusion not specified
  • p. 12: Note that the Angle classification has four classes: normal occlusion, Class I malocclusion, Class II malocclusion, and Class III malocclusion (see Fig. 1.3). Normal occlusion and Class I malocclusion share the same molar relationship but differ in the arrangement of the teeth relative to the line of occlusion. The line of occlusion may or may not be correct in Class II and Class III malocclusion.
  • p. 12: occlusion, Class I malocclusion, Class II malocclusion, and Class III malocclusion (see Fig. 1.3). Normal occlusion and Class I malocclusion share the same molar relationship but differ in the arrangement of the teeth relative to the line of occlusion
  • p. 13:
  • p. 13:
  • p. 13: The line of occlusion is a smooth (catenary) curve passing through the central fossa of each upper molar and across the cingulum of the upper canine and incisor teeth. The same line runs along the buccal cusps and incisal edges of the lower teeth, thus specifying the occlusal as well as interarch relationships once the molar position is established

The Changing Goals of Orthodontic Treatment > Modern Treatment Goals: The Soft Tissue Paradigm

  • p. 14: The primary goal of treatment becomes soft tissue relationships and adaptations, not Angle’s ideal occlusion.
  • p. 14: The secondary goal of treatment becomes functional occlusion. What does that have to do with soft tissues? Temporomandibular (TM) dysfunction, to the extent that it relates to the dental occlusion, is best thought of as the result of injury to the soft tissues around the temporomandibular joint (TMJ) caused by clenching and grinding the teeth
  • p. 14: The thought process that goes into “solving the patient’s problems” is reversed. In the past, the clinician’s focus was on dental and skeletal relationships, with the tacit assumption that if these were correct, soft tissue relationships would take care of themselves
  • p. 14: Why is this important in establishing the goals of treatment? It relates very much to why patients and parents seek orthodontic treatment and what they expect to gain from it
  • p. 14: As time passed, it became clear that even an excellent occlusion was unsatisfactory if it was achieved at the expense of proper facial proportions
  • p. 14: extraction of teeth was reintroduced into orthodontics in the 1940s and 1950s to enhance facial esthetics and achieve better stability of the occlusal relationships.
  • p. 14: By use of cephalometrics, it also was possible to see that jaw growth could be altered by orthodontic treatment.
  • p. 14: The changes in the goals of orthodontic treatment, which now focus on facial proportions and the impact of the dentition on facial appearance, have been codified in the form of the soft tissue paradigm.
  • p. 14: Modern Treatment Goals: The Soft Tissue Paradigm
  • p. 14: The soft tissue paradigm states that both the goals and limitations of modern orthodontic and orthognathic treatment are determined by the soft tissues of the face, not by the teeth and bones

The Usual Orthodontic Problems: Epidemiology of Malocclusion

  • p. 15: For that reason, when defining the goals of orthodontic treatment, one has to consider not only morphologic and functional factors, but a wide range of psychosocial and bioethical issues as wel
  • p. 15: The characteristics of malocclusion evaluated in NHANES III included the irregularity index, which is a measure of incisor alignment (Fig. 1.4); the prevalence of midline diastema larger than 2 mm (Fig. 1.5); and the prevalence of posterior crossbite (Fig. 1.6). In addition, overjet (Fig. 1.7) and overbite or open bite (Fig. 1.8) were measured. Overjet reflects Angle’s Class II and Class III molar relationships. Because overjet can be evaluated much more precisely than molar relationship in a clinical examination, molar relationship was not evaluated directly.
  • p. 15: Nearly 15% of adolescents and adults have severely or extremely irregular incisors, so that major arch expansion or extraction of some teeth would be necessary to align them
  • p. 16: Overjet or reverse overjet indicates anteroposterior deviations in the Class II or Class III direction, respectively, with Class III being much less prevalent (Fig. 1.12)
  • p. 16: Occlusal relationships must be considered in all three planes of space. Lingual posterior crossbite (i.e., upper teeth lingual to lower teeth; see Fig. 1.6) is the major deviation from the normal transverse dental relationship and reflects deviations from ideal occlusion in the transverse plane of space
  • p. 16:
  • p. 16: Fig. 1.8 Overbite is defined as the vertical overlap of the incisors. Normally, the lower incisal edges contact the lingual surface of the upper incisors at or above the cingulum (i.e., normally there is a 1- to 2-mm overbite). In open bite, there is no vertical overlap, and the vertical separation of the incisors is measured to quantify its severity.
  • p. 16:
  • p. 16: Fig. 1.7 Overjet is defined as horizontal overlap of the incisors. Normally the incisors are in contact, with the upper incisors ahead of the lower by only the thickness of their incisal edges (i.e., overjet of 2 to 3 mm is the normal relationship). If the lower incisors are in front of the upper incisors, the condition is called reverse overjet or anterior crossbite.

Why Is Malocclusion So Prevalent?

  • p. 17: Crowded and irregular teeth now occur in a majority of the population; skeletal remains indicate that this was unusual until relatively recently, although not unknown
  • p. 17: The skeletal remains suggest that all members of a group might tend toward a Class III or, less commonly, a Class II jaw relationship.
  • p. 18: It is easy to see that the progressive reduction in jaw size, if not well matched to a decrease in tooth size and number, could lead to crowding and malalignmen

Who Needs Treatment?

  • p. 19: Who Needs Treatment?
  • p. 19: Protruding, irregular, or maloccluded teeth can cause three types of problems for the patient: (1) social discrimination because of facial appearance; (2) problems with oral function, including difficulties in jaw movement (muscle incoordination or pain),
  • p. 19: One can argue that malocclusion is another condition made worse by the changing conditions of modern life, perhaps resulting in part from less use of the masticatory apparatus with softer foods now.
  • p. 19: Watching an Australian aboriginal man using every muscle of his upper body to tear off a piece of kangaroo flesh from the barely cooked animal, for instance, makes one appreciate the decrease in demand on the masticatory apparatus that has accompanied civilization (Fig. 1.17)

Who Needs Treatment? > Psychosocial Problems

  • p. 20: Although severe malocclusion surely affects oral function, oral function adapts to form surprisingly well.
  • p. 20: Tongue and lip posture adapt to the position of the teeth so that swallowing rarely is affected
  • p. 20: Some types of malocclusion (especially posterior crossbite with a shift on closure) correlate positively with TMJ problems and other types do not, but even the strongest correlation coefficients are only 0.3 to 0.4. This means that for the great majority of patients, there is no association between malocclusion and TMD.
  • p. 20: temporomandibular dysfunction (TMD), and problems with mastication, swallowing, or speech; and (3) greater susceptibility to trauma, periodontal disease, or tooth decay.
  • p. 20: In short, it seems clear that the major reason people seek orthodontic treatment is to minimize psychosocial problems related to their dental and facial appearance

Type of Treatment: Evidence-Based Selection > Randomized Clinical Trials: The Best Evidence

  • p. 21: but with previous trauma and age younger than 9 years, the risk of additional trauma is 8.4 times higher than in children with no history of trauma.
  • p. 21: 22 For such a child, retracting the incisors (but not growth modification) is indicated
  • p. 21: If individuals with malocclusion are more prone to tooth decay, the effect is small compared with hygiene status

Demand for Treatment > Epidemiologic Estimates of Orthodontic Treatment Need

  • p. 23:
  • p. 23: contact point displacements less than 1 m
  • p. 23: mm
  • p. 23: Index of Treatment Needs (IOTN) Treatment Grades •
  • p. 23: Demand for Treatment Epidemiologic Estimates of Orthodontic Treatment Need
  • p. 23: There now are two major methods for scoring the severity of malocclusion: the peer assessment rating (PAR) system, developed in the United Kingdom, and the American Board of Orthodontics (ABO) discrepancy index, developed in the United States
  • p. 23: The Index of Treatment Need (IOTN), developed by Brook and Shaw in the United Kingdom,28 was designed to evaluate need for treatment. It places patients in five grades from “no need for treatment” to “treatment required” that correlate reasonably well with clinician’s judgments of need for treatment.
  • p. 23: and

Demand for Treatment > Who Seeks Treatment?

  • p. 25: Often, we lose track of that simple truth by trying to justify orthodontic treatment at a higher and seemingly more significant level. In fact, people value straight teeth because it makes their lives easier and better.

References

  • p. 26: As the population ages, these older adults are likely to be the fastest growing group who seek orthodontic treatment.
  • p. 26: It seems likely that under optimal economic conditions, demand for orthodontic treatment will at least reach the 35% level thought by the public to need treatment. In higher socioeconomic areas in the United States, 35% to more than 50% of children and youths now are receiving orthodontic care

2 Concepts of Growth and Development

The Nature of Skeletal Growth

  • p. 30: The Nature of Skeletal Growth | Comment: Reading of L1 UA Theories of physical growth (read all the way up to the end of “theories of growth control” )
  • p. 30: At the cellular level, there are only three possibilities for growth. The first is an increase in the size of individual cells, which is referred to as hypertrophy. The second possibility is an increase in the number of the cells, which is called hyperplasia. The third is secretion of extracellular material,
  • p. 30: The fact that the extracellular material of the skeleton becomes mineralized leads to an important distinction between growth of the soft or nonmineralized tissues of the body and the hard or calcified tissues.
  • p. 30: hard tissue. Growth of soft tissues occurs by a combination of hyperplasia and hypertrophy. These processes go on everywhere within the tissues, and the result is what is called interstitial growth,
  • p. 30: In contrast, when mineralization takes place so that hard tissue is formed, interstitial growth becomes impossible
  • p. 30: mineralized tissues, these processes can occur only on the surface, not within the mineralized mass.
  • p. 30: Cartilaginous skeletal development occurs most rapidly during the third month of intrauterine life.
  • p. 31: Not all bones of the adult skeleton were represented in the embryonic cartilaginous model, and it is possible for bone to form by secretion of bone matrix directly within connective tissues, without any intermediate formation of cartilage. Bone formation of this type is called intramembranous ossification.
  • p. 31: he mandible of higher animals develops in the same area as the cartilage of the first pharyngeal arch—Meckel’s cartilage.
  • p. 31: During the fourth month in utero, there is an ingrowth of blood vascular elements into various points of the chondrocranium (and the other parts of the early cartilaginous skeleton). These areas become centers of ossification, at which cartilage is transformed into bone in the process called endochondral ossification

Sites and Types of Growth in the Craniofacial Complex

  • p. 32: Sites and Types of Growth in the Craniofacial Complex
  • p. 32: In the following discussion of sites and types of growth in the head and face, it is convenient to divide the craniofacial complex into four areas that grow rather differently: the cranial vault, the bones that cover the upper and outer surface of the brain; the cranial

Sites and Types of Growth in the Craniofacial Complex > Cranial Vault

  • p. 33: base, the bony floor under the brain, which also is the dividing line between the cranium and the face; the nasomaxillary complex, made up of the nose, maxilla, and associated small bones; and the mandible
  • p. 33: The cranial vault is made up of a number of flat bones that are formed directly by intramembranous bone formation
  • p. 33: Modeling (addition of new bone) and growth occur primarily at the periosteum-lined contact areas between adjacent skull bones, the cranial sutures,
  • p. 33: Despite their small size, apposition of new bone at these sutures is the major mechanism for growth of the cranial vault.
  • p. 33: Although the majority of growth in the cranial vault occurs at the sutures, there is a tendency for bone to be removed from the inner surface of the cranial vault, while at the same time new bone is added on the exterior surface. This modeling of the inner and outer surfaces allows for changes in contour during growth.
  • p. 33: Cranial Base
  • p. 33: As ossification proceeds, bands of cartilage called synchondroses remain between the centers of ossification (Fig. 2.25). These important growth sites are the synchondrosis between the sphenoid and occipital bones, or spheno-occipital synchondrosis; the intersphenoid synchondrosis between two parts of the sphenoid bone; and the spheno-ethmoidal synchondrosis between the sphenoid and ethmoid bones

Sites and Types of Growth in the Craniofacial Complex > Maxilla (Nasomaxillary Complex)

  • p. 34: Because there is no cartilage replacement, growth occurs in two ways: (1) by apposition of bone at the sutures that connect the maxilla to the cranium and cranial base and (2) by surface modeling and remodeling
  • p. 34: e growth pattern of the face requires that it grow “out from under the cranium,” which means that as it grows, the maxilla must move a considerable distance downward and forward relative to the cranium and cranial base
  • p. 34: As Fig. 2.27 illustrates, the sutures attaching the maxilla posteriorly and superiorly are ideally situated to allow its downward and forward repositioning.

Sites and Types of Growth in the Craniofacial Complex > Mandible

  • p. 35: To understand this seeming paradox, it is necessary to comprehend that two quite different processes are going on simultaneously. The overall growth changes are the result of both a downward and forward translation of the maxilla and a simultaneous surface modeling
  • p. 35: The effect is additive, for instance, on the roof of the mouth. This area is carried downward and forward along with the rest of the maxilla, but at the same time, bone is removed on the nasal side and added on the oral side, thus creating an additional downward and forward movement of the palate (Fig. 2.30).
  • p. 35: n contrast to the maxilla, both endochondral and periosteal activity are important in growth of the mandible,

Sites and Types of Growth in the Craniofacial Complex > Facial Soft Tissues > Growth of the Lips

  • p. 36: rest (often termed lip incompetence) is maximal during childhood

Sites and Types of Growth in the Craniofacial Complex > Facial Soft Tissues > Growth of the Nose

  • p. 37: Three major theories in recent years have attempted to explain the determinants of craniofacial growth: (1) bone, like other tissues, is the primary determinant of its own growth; (2) cartilage is the primary determinant of skeletal growth, while bone responds secondarily and passively; and (3) the soft tissue matrix in which the skeletal elements are embedded is the primary determinant of growth, and both bone and cartilage are secondary followers.
  • p. 37: n contemporary thought, the truth is to be found in some synthesis of the second and third theories;
  • p. 37: Distinguishing between a site of growth and a center of growth clarifies the differences between the theories of growth control.
  • p. 37: It is clear now that sutures, and the periosteal tissues more generally, are not primary determinants of craniofacial growth. Two lines of evidence lead to this conclusion. The first is that when an area of the suture between two facial bones is transplanted
  • p. 37: Lip thickness reaches its maximum during adolescence, then decreases
  • p. 37: Growth of the nasal bone is complete at about age 10.
  • p. 37: Growth thereafter is only of the nasal cartilage and soft tissues,
  • p. 37: it is an obvious error to emphasize endochondral bone formation at the condyle as the major mechanism for growth of the mandible.

Theories of Growth Control > Cartilage as a Determinant of Craniofacial Growth

  • p. 38: to another location (to a pouch in the abdomen, for instance), the sutural tissue does not continue to grow. This indicates a lack of innate growth potential in the sutures. Second, it can be seen that growth at sutures will respond to outside influences under a number of circumstances.
  • p. 39: Growth of the maxilla is more difficult but not impossible to explain on a cartilage theory basis. Although there is no cartilage in the maxilla itself, there is cartilage in the nasal septum, and the nasomaxillary complex grows as a unit. Proponents of the cartilage theory hypothesize that the cartilaginous nasal septum serves as a pacemaker for other aspects of maxillary growth
  • p. 39: he cartilage at the condyle of the mandible could be considered as a pacemaker for growth of that bone and the modeling of the ramus and other surface changes could be viewed as secondary to the primary cartilaginous growth.

Theories of Growth Control > Functional Matrix Theory of Growth

  • p. 42: In summary, it appears that epiphyseal cartilages and (probably) the cranial base synchondroses can and do act as independently growing centers, as can the nasal septum (perhaps to a lesser extent). Transplantation experiments and experiments in which the condyle is removed lend no support to the idea that the cartilage of the mandibular condyle is an important growth center and neither do studies of the cartilage itself in comparison to primary growth cartilage. It appears that growth at the mandibular condyles is much more analogous to growth at the sutures of the maxilla—which is entirely reactive—than to growth at an epiphyseal plate.
  • p. 42: This phenomenon can be seen readily in humans in two experiments of nature (Fig. 2.41). First, when the brain is very small, the cranium is also very small, and the result is microcephaly (which is now seen much more frequently because of Zika virus infections in pregnant women that interfere with neural growth in the fetus). In this case, the size of the head is an accurate representation of the size of the brain. A second natural experiment is hydrocephaly. In this case, reabsorption of cerebrospinal fluid is impeded, the fluid accumulates, and intracranial pressure builds up. The increased intracranial pressure impedes development of the brain, so the hydrocephalic may have a small brain and be mentally retarded; but this cond
  • p. 45: e bone of the mandible is quite similar in its internal structure to the bone of the limbs, even though its developmental course is rather different.
  • p. 45: The bone of the mandible is quite similar in its internal structure to the bone of the limbs, even though its developmental course is rather different. Lengthening the mandible via distraction osteogenesis clearly is possib
  • p. 45: a c

Social and Behavioral Development > Learning and the Development of Behavior > Classical Conditioning

  • p. 47: As a general rule, the older the individual, the more complex the behavioral pattern and the more important the learned overlay of behavior will be.
  • p. 47: s learning proceeds, more complex skills and behaviors appear, but it is difficult to define the process in distinct stages—a continuous flow model appears more appropriate.

Social and Behavioral Development > Learning and the Development of Behavior > Operant Conditioning

Social and Behavioral Development > Learning and the Development of Behavior > Observational Learning (Modeling)

  • p. 51: lings, other children, or even parents. There are two distinct stages in observational learning: acquisition of the behavior by observing it and the actual performance of that behavior. A child can observe many behaviors and thereby acquire the potential to perform them, without immediately demonstrating or performing that behavior.

Social and Behavioral Development > Stages of Emotional and Cognitive Development > Emotional Development > 1. Development of Basic Trust (Birth to 18 Months).

  • p. 52: If it is necessary to provide dental treatment at an early age, it usually is preferable to do so with the parent present and, if possible, while the child is being held by one of the parents.
  • p. 52: At later ages, a child who never developed a sense of basic trust will have difficulty entering into situations that require trust and confidence in another person. Such an individual is likely to be an extremely frightened and uncooperative patient who needs special effort to establish rapport and trust with the dentist and staff, and having a parent present in the treatment area during initial visits can be helpful (Fig. 2.55).
  • p. 52: This, of course, is similar to what also happens in physical development. Rather differently from physical development, it is possible and indeed probable that qualities associated with earlier stages may be evident in later stages because of incomplete resolution of the earlier stages.

Social and Behavioral Development > Stages of Emotional and Cognitive Development > Emotional Development > 3. Development of Initiative (3 to 6 Years).

  • p. 53: 3. Development of Initiative (3 to 6 Years).
  • p. 53: The initiative is shown by physical activity and motion, extreme curiosity and questioning, and aggressive talking.
  • p. 53: At this stage, a child is inherently teachable
  • p. 53: eager modeling of behavior o
  • p. 53: In Erikson’s view, the child’s ultimate ability to initiate new ideas or activities depends on how well he or she is able at this stage to express new thoughts and do new things without being made to feel guilty about expressing a bad idea or failing to achieve what was expected
  • p. 53: Annotation
  • p. 53: developing a sense of individual identity or autonomy
  • p. 53: The parents and other adults with whom the child reacts at this stage must protect him against the consequences of dangerous and unacceptable behavior, while providing opportunities to develop independent behavior
  • p. 53: oubt and shame.”22 A key toward obtaining cooperation with treatment from a child at this stage is to have the child think that whatever the dentist wants was his or her own choice, not something required by another person.

Social and Behavioral Development > Stages of Emotional and Cognitive Development > Emotional Development > 4. Mastery of Skills (7 to 11 Years).

  • p. 54: At this stage, orthodontic treatment should be instituted only if the patient wants it, not just to please the parents
  • p. 54: Orthodontic treatment often begins during this stage of development.

Social and Behavioral Development > Stages of Emotional and Cognitive Development > Emotional Development > 6. Development of Intimacy (Young Adult).

  • p. 55: but another aspect of the same responsibility is service to the group, community, and nation.

3 Early Stages of Development

Infancy and Early Childhood: The Primary Dentition Years > Eruption of the Primary Teeth

  • p. 65: Occasionally a “natal tooth” is present, although the first primary teeth normally do not erupt until approximately 6 months of age.
  • p. 65: but usually is merely a very early but otherwise normal central incisor
  • p. 65: The dates of eruption are relatively variable; up to 6 months of acceleration or delay is within the normal range. Preterm infants typically have some delay,11 and there is some v

Late Childhood: The Mixed Dentition Years > Physical Development in Late Childhood

  • p. 66: Spaces between the teeth are normal throughout the anterior part of the primary dentition but are most noticeable in two locations, called the primate spaces. (Most subhuman primates have these spaces throughout life; thus the name.) In the maxillary arch the primate space is located between the lateral incisors and canines, whereas in the mandibular arch the space is between the canines and first molars (Fig. 3.10)

Late Childhood: The Mixed Dentition Years > Eruption of the Permanent Teeth > Preemergent Eruption

  • p. 67: Two processes are necessary for preemergent eruption. First, there must be resorption of bone and primary tooth roots overlying the crown of the erupting tooth; second, a propulsive mechanism then must move the tooth in the direction where the path has been cleared
  • p. 67: appropriately labeled ia, for incisors absent. In these animals a lack of bone resorption means that the incisor teeth cannot erupt, and they never appear in the mouth. Failure of teeth to erupt because of a failure of bone resorption also occurs in humans, as for instance in the syndrome of cleidocranial dysplasia
  • p. 67: (1) the improvement in assessing growth status relative to peak growth at adolescence from using hand–wrist radiographs, if any, is not worth the extra radiation except in special circumstances, and (2) CVM is a better predictor for timing of the adolescence growth spurt than chronologic age.
  • p. 69: Normally, the rate of eruption is such that the apical area remains at the same place while the crown moves occlusally, but if eruption is mechanically blocked, the proliferating apical area will move in the opposite direction, inducing resorption where it usually does not occur (Fig. 3.17). This often causes a distortion of root form, which is called dilaceration.
  • p. 71: Despite many years of study, the precise mechanism through which the propulsive force is generated remains unknown. It appears that the mechanism of eruption before the emergence of a tooth into the mouth and the mechanism after a tooth has emerged are different

Late Childhood: The Mixed Dentition Years > Eruption of the Permanent Teeth > Postemergent Eruption

  • p. 72: As the mandible continues to grow, it moves away from the maxilla, creating a space into which the teeth erupt. Exactly how eruption is controlled so that it matches mandibular growth, however, is not known, and because some of the more difficult orthodontic problems arise when eruption does not coincide with growth, this is an important area for further study.
  • p. 72: The stage of relatively rapid eruption from the time a tooth first penetrates the gingiva until it reaches the occlusal level is called the postemergent spurt, in contrast to the following phase of very slow eruption, termed the juvenile occlusal equilibrium

Late Childhood: The Mixed Dentition Years > Eruption Sequence and Timing: Dental Age

  • p. 74: Light pressures of long duration are more important in producing orthodontic tooth movemen
  • p. 74: Eruption Sequence and Timing: Dental Age
  • p. 75: Chronology of Tooth Development, Permanent Dentition

Late Childhood: The Mixed Dentition Years > Space Relationships in Replacement of the Incisors

  • p. 78: Several reasonably normal variations in eruption sequence have clinical significance and should be recognized. These are (1) eruption of second molars ahead of premolars in the mandibular arch, (2) eruption of canines ahead of premolars in the maxillary arch, and (3) unusually large asymmetries in eruption between the right and left sides.

4 Later Stages of Development

Growth Patterns in the Dentofacial Complex > Dimensional Changes > Growth of the Nasomaxillary Complex

  • p. 88: As we have noted in the preceding chapters, growth of the nasomaxillary area is produced by two basic mechanisms: (1) passive displacement, created by growth in the cranial base that pushes the maxilla forward, and (2) active growth of the maxillary structures and nose (Fig. 4.7). Because the push from behind decreases greatly as the cranial base synchondroses close at about age 7, most of the growth after that time (i.e., during the time period when most orthodontic treatment is done) is due to active growth at the maxillary sutures and surfaces.
  • p. 88: For this reason, the distance that the body of the maxilla and the maxillary teeth are carried downward and forward during growth is greater by about 25% than the forward movement of the anterior surface of the maxilla.
  • p. 88: axilla and the maxillary teeth are carried downward and forward during growth is greater by about 25% than the forward movement of the anterior surface of the maxilla. This amount of surface modeling, which conceals the extent of relocation of the jaws, is even more prominent when rotation of the maxilla during growth is considered (see the following sections). The nasal structures undergo the same passive d
  • p. 88: e anterior surface of the maxilla. This amount of surface modeling, which conceals the extent of relocation of the jaws, is even more prominent when rotation of the maxilla during growth is considered (see the following sections). The nasal structures undergo the same passive displa
  • p. 88: ramus height increases 1 to 2 mm per year and body length increases 2 to 3 mm per year. These cross-sectional data tend to smooth out the juvenile and pubertal growth spurts, which do occur in growth of the mandible (see previous discussion).
  • p. 88: Although small amounts of bone are added, the change in the contour of the chin itself occurs largely because the area just above the chin, between it and the base of the alveolar process, is a resorptive area.

Growth Patterns in the Dentofacial Complex > Dimensional Changes > Timing of Growth in Width, Length, and Height

  • p. 89: ches, tends to be completed before the adolescent growth spurt and is affected minimally if at all by adolescent growth changes (Fig. 4.11). For instance, intercanine width is more likely to decrease than increa
  • p. 89: after age
  • p. 89: s the jaws

Growth Patterns in the Dentofacial Complex > Rotation of Jaws During Growth > Implant Studies of Jaw Rotation

  • p. 90: e reason is that the rotation that occurs in the core of each jaw, called internal rotation, tends to be masked by surface changes and alterations in the rate of tooth eruption. The surface changes produce external rotation. Obviously, the overall change in the orientation of each jaw, as
  • p. 90: In girls, the maxilla grows slowly downward and forward to age 14 to 15 on average (more accurately, by 2 to 3 years after first menstruation), then tends to grow slightly more almost straight forward (Fig. 4.12)
  • p. 90: ial height and concomitant eruption of teeth continue throughout life, but the decline to the adult level (which for vertical growth is surprisingly large [see the following section]) often does not occur until the early 20s in boys and somewhat earlier in girls. Rotation of Jaws D
  • p. 92: forwa
  • p. 92: e rotation is “backward” and given a positive direction if it lengthens anterior dimensions more than posterior ones, bringing the chin downward and bac
  • p. 92: it can be observed that in most individuals, the core of the mandible rotates during growth in a way that would tend to decrease the mandibular plane angle (i.e., up anteriorly and down posteriorly) (Fig. 4.1
  • p. 92: y convention, the rotation of either jaw is considered “forward” and given a negative sign if there is more growth posteriorly than anteriorly. This would bring the chin upward an
  • p. 92: erminology: Rotational Changes of the Jaws
  • p. 94: Individuals of the short-face type, who are characterized by short anterior lower face height, have excessive forward rotation of the mandible during growth, resulting from both an increase in the normal internal rotation and a decrease in external compensation. The result is a nearly horizontal palatal plane, a low mandibular plane angle, and a large gonial angle (Fig. 4.18). A deep bite malocclusion and crowded incisors usually accompany this type of rotation (discussed later)
  • p. 94: Individuals of the short-face type, who are characterized by short anterior lower face height, have excessive forward rotation of the mandible during growth, resulting from both an increase in the normal internal rotation and a decrease in external compensation. | Comment: stopped here
  • p. 94: Annotation
  • p. 94: Annotation

Growth Patterns in the Dentofacial Complex > Rotation of Jaws During Growth > Interaction Between Jaw Rotation and Tooth Eruption

  • p. 95: Forward rotation would tend to tip the incisors forward, increasing their prominence, whereas backward rotation directs the anterior teeth more posteriorly, relatively uprighting them and decreasing their prominence.

Maturational and Aging Changes > Facial Growth in Adults

  • p. 96: The modern view places relatively greater importance on lingual movement of the incisors and relatively less importance on the forward movement of mol
  • p. 96: This is why there is a strong tendency for deep bite malocclusion in short-face individuals (Fig. 4.23).
  • p. 96: ecause the forward internal rotation of the mandible is greater than that of the maxilla, it is not surprising that the normal decrease in mandibular arch length is somewhat greater than the decrease in maxillary arch length.
  • p. 97: CHAPTER 4 Later Stages of Development 97 B A
  • p. 97: The results were surprising but unequivocal: facial growth had continued during adult life (Fig. 4.24). There was an increase in essentially all the facial dimensions, but both size and shape of the craniofacial complex altered with time.
  • p. 97: The changes involved an elongation of the nose (which often became significantly longer during adult life), flattening of the lips, and an augmentation of the soft tissue chin

Maturational and Aging Changes > Changes in Facial Soft Tissues

  • p. 98: With a coarse diet, not only did occlusal wear reduce the height of the crowns, but also the width of teeth was reduced as interproximal wear occurre | Comment: in class he said this is just a theory and a super mid one, essentially to discount it !
  • p. 98: but width changes thereafter are quite low.1
  • p. 98: e result is a decrease in exposure of the upper incisors and an increase in exposure of the lower incisors,

Maturational and Aging Changes > Changes in Alignment and Occlusion

  • p. 101: 1. Lack of “normal attrition” in the modern diet.
  • p. 101: Pressure from third molars.
  • p. 101: 3. Late mandibular growth.

5 The Etiology of Orthodontic Problems

Specific Causes of Malocclusion > Disturbances in Embryologic Development

  • p. 117:
  • p. 117: Specific Causes of Malocclusion
  • p. 117: Disturbances in Embryologic Development
  • p. 118: Genetic and environmental insults (in this context, insult means anything that could have an adverse impact on normal development) can affect the developing face and jaws throughout the embryonic period. It usually is the case that an insult affected growth well before

Specific Causes of Malocclusion > Growth Disturbances in the Fetal and Perinatal Period > Fetal Molding and Birth Injuries > Intrauterine Molding. > Birth Trauma to the Mandible.

  • p. 125: Progressive Deformities in Childhood
  • p. 125: Childhood Fractures of the Jaws
  • p. 125: Unilateral condylar fracture is much more frequent than bilateral fractures
  • p. 125: When a problem does arise following condylar fracture, it usually is asymmetric growth deficiency, with the injured side (or, in bilateral fractures, the more severely injured side) lagging behind (Fig. 5.14
  • p. 125: This concept is highly relevant to the management of condylar fractures in children. It suggests, and clinical experience confirms, that there would

Specific Causes of Malocclusion > Progressive Deformities in Childhood > Muscle Dysfunction

  • p. 126: Occasionally, unilateral excessive growth of the mandible occurs in individuals who seem metabolically norma
  • p. 126: The condition formerly was called condylar hyperplasia, and proliferation of the condylar cartilage is a prominent aspect; however, because the body of the mandible also is affected (Fig. 5.19), hemimandibular hypertrophy now is considered a more accurate descriptive term
  • p. 126: Disturbances of Dental Development
  • p. 126: Most disturbances of dental development are contributors to isolated Class I malocclusion,
  • p. 126: Congenitally Missing Teeth
  • p. 126: Muscle Dysfunction

Genetic Influences

  • p. 131: Certain types of malocclusion run in families

Environmental Influences > Equilibrium Considerations

  • p. 134: Environmental influences during growth and development of the face, jaws, and teeth consist largely of pressures and forces related to physiologic activi
  • p. 134: A key consideration is that the supporting structures of the dentition (periodontal ligament [PDL] and alveolar bone) are constructed to withstand heavy forces of short duration such as those from mastication
  • p. 134: Only if pressure is maintained long enough to squeeze out the fluid (a few seconds) is there an impact on the soft tissues
  • p. 134: Using twins with siblings as controls, Hughes et al reported that the hereditary component for variations in spacing and tooth position within the dental arches was 69% to 89%. It was 53% for overbite, but only 28% for overjet (which therefore appears to have a greater environmental component than crowding/spacing or overbite).21 Corruccini et al have argued that with appropriate corrections for unsuspected environmental differences within twin pairs, the heritability for some dental characteristics such as overjet is almost zero
  • p. 134: From an examination of longitudinal cephalometric radiographs and dental casts of siblings who participated in the Bolton-Brush growth study, Harris and Johnson concluded that the heritability of craniofacial (skeletal) characteristics was relatively high but that of dental (occlusal) characteristics was low.
  • p. 134: For skeletal characteristics, the heritability estimates increased with increasing age; for dental characteristics, the heritability estimates decreased, indicating an increasing environmental contribution to the dental variation.
  • p. 134: As was noted in European royal families (see Fig. 5.25), the influence of inherited tendencies is particularly strong for mandibular prognathism

Environmental Influences > Masticatory Function

  • p. 135: 1) greater use of the jaws, with higher and/or more prolonged biting force, could increase the dimensions of the jaws and dental arches, or (2) less use of the jaws might lead to underdeveloped dental arches and crowded

Environmental Influences > Masticatory Function > Function and Dental Arch Size

  • p. 136: During the development of a single individual, vertical jaw relationships clearly are affected by muscular activity
  • p. 136: Animal experiments with soft versus hard diets have shown that morphologic changes can occur within a single generation when diet consistency is altered
  • p. 136: Patients who have excessive overbite or anterior open bite usually have posterior teeth that are infra- or supra-erupted
  • p. 136: It was noted some years ago that short-face individuals have higher and long-face persons lower maximum biting forces than those with normal vertical dimensions
  • p. 136: an association between facial morphology and occlusal force does not prove a cause-and-effect relationsh
  • p. 136: The size and shape of the muscular processes of the jaws reflect muscle size and activity. For example, enlargement of the mandibular gonial angles can be seen in humans with hypertrophy of the mandibular elevator muscles

Environmental Influences > Sucking and Other Habits

  • p. 137: however, malocclusion characterized by flared and spaced maxillary incisors, lingually positioned lower incisors, anterior open bite, and a narrow upper arch is the likely resul
  • p. 137: pattern of resting cheek and lip pressures.33 When a child places a thumb or finger between the teeth, it is usually positioned at an angle so that it presses lingually against the lower incisors and labially against the upper incisors
  • p. 139: Although negative pressure is created within the mouth during sucking, there is no reason to believe that this is responsible for the narrowing of the maxillary arch that usually accompanies sucking habits. Instead, arch form is affected by an alteration in the balance between cheek and tongue pressures. If the thumb is placed between the teeth, the tongue must be lowered, which decreases pressure by the tongue against the lingual of upper posterior teeth
  • p. 139:

Environmental Influences > Tongue Thrusting

  • p. 140: The term tongue thrust is therefore something of a misnomer because it implies that the tongue is forcefully thrust forward. Swallowing is not a learned behavior but is integrated and controlled physiologically at subconscious levels, so whatever the pattern of swallow, it cannot be considered a habit in the usual sense
  • p. 140: Because coordinated movements of the posterior tongue and elevation of the mandible tend to develop before protrusion of the tongue tip between the incisor teeth disappears, what is called “tongue thrusting” in young children is often a normal transitional stage in swallowing
  • p. 140: In other words, a tongue thrust swallow is a useful physiologic adaptation if you have an open bite, which is why an individual with an open bite usually also has a tongue thrust swallow, but protruding the tongue between the anterior teeth during swallowing is often present in children with good anterior occlusion

Environmental Influences > Respiratory Pattern

  • p. 141: Tongue thrust swallowing simply has too short a duration to have an impact on tooth position. Pressure by the tongue against the teeth during a typical swallow lasts for approximately 1 second

6 Orthodontic Diagnosis

Questionnaire and Interview > Chief Concern

  • p. 150: Orthodontic diagnosis requires a broad overview of the patient’s situation and must take into consideration both objective and subjective findings. It is important not to characterize the dental occlusion while overlooking a jaw discrepancy, developmental syndrome, systemic disease, periodontal problem, psychosocial problem, or the cultural milieu in which the patient is living.
  • p. 151: there are three major reasons for patient concern about the alignment and occlusion of the teeth: impaired dentofacial appearance and a diminished sense of social well-being, impaired function, and impaired oral health
  • p. 151: When patients inquire about whether they need orthodontic treatment, a series of leading questions should be asked, beginning with, “Do you think you need braces?” If the answer is yes, one might next inquire “What bothers you more about your teeth, your bite or your appearance?” and “What do you want treatment

Questionnaire and Interview > Medical and Dental History

  • p. 152: First, although most children with a condylar fracture of the mandible recover uneventfully, remember that a growth deficit related to an old injury is the most probable cause of true facial asymmetry (F
  • p. 152: Second, it is important to note whether the patient is on longterm medication of any type and, if so, for what purpose. This may reveal systemic disease or metabolic problems that the patient did not report in any other way.
  • p. 152: A second major area that should be explored with questions to the patient or parents is the individual’s physical growth statu
  • p. 152: to do for you?” The answer to that and follow-up questions will clarify what is most important to the patient
  • p. 152: Orthodontic problems are almost always the culmination of a developmental process, not the result of a pathologic condition

Questionnaire and Interview > Physical Growth Evaluation

  • p. 154: the gradient of facial growth discussed i
  • p. 154: If a child is being followed for referral to an orthodontist at the optimum time or by an orthodontist for observation of growth before beginning treatment, height and weight changes can provide insight into the patient’s overall growth status and mandibular growth status, given that statural growth and mandibular growth

Questionnaire and Interview > Social and Behavioral Evaluation

  • p. 155: Internal motivation, on the other hand, comes from within the individual and is based on his or her own assessment of the situation and desire for treatmen
  • p. 155: Although now some preadolescent children express a desire to have “an appliance” or “braces” because many of their peers are having early treatment, it is rare to find strong internal motivation in that age grou
  • p. 155: are generally related
  • p. 155: Another approach is to get an estimate of how much mandibular growth remains, which would be especially important for a child with a skeletal Class II problem who would benefit from orthodontic treatment to modify growth if that is possible
  • p. 155: If vertebral maturation shows delayed skeletal development, the mandibular growth spurt probably still is in the future. The stage of dental development should not be used to estimate the stage of jaw growth.

Clinical Evaluation > Oral Health

  • p. 156: It is particularly easy to fail to notice a missing or supernumerary lower incisor
  • p. 156: In the periodontal evaluation, there are two major points of interest: indications of active periodontal disease, and potential or actual mucogingival problems. The patient’s oral hygiene status should be recorded and documented by clinical photographs
  • p. 156: The developmental status of the patient applies not only to the eruption of teeth and growth of the jaws, but also to the quality of the teeth. T
  • p. 156: There are two goals of the orthodontic clinical examination: to (1) evaluate and document oral health, jaw function, facial proportions, and smile characteristics and (2) decide which diagnostic records are required

8 The Biologic Basis of Orthodontic Therapy

Periodontal Ligament and Bone Response to Sustained Force > Biologic Control of Tooth Movement > Biologic Electricity

  • p. 250: In other circumstances, a somewhat higher threshold, but still one of only a few grams, seems to exist. The current concept is that active stabilization can overcome prolonged forces of a few grams at most, perhaps up to the 5 to 10 gm/cm2 often observed as the magnitude of unbalanced soft tissue resting pressures.
  • p. 250: Role of the Periodontal Ligament in Eruption and Stabilization of the Teeth
  • p. 250: After a tooth emerges into the mouth, further eruption depends on metabolic events within the PDL, including but perhaps not limited to formation, cross-linkage, and maturational shortening of collagen fibers (see Chapter 3).
  • p. 250: apparent quiescence. The continuing presence of this mechanism indicates that it may produce not only eruption of the teeth under appropriate circumstances but also active stabilization of the teeth against prolonged forces of light magnitude.

Timing in Relation to the Amount of Growth Remaining

Unmapped Annotations

  • p. ifc1: Any screen. Any time. Anywhere. | Comment: Test annotation

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