05 - Maturational Changes

Introduction

Purpose of this Program

In this program we discuss changes that occur in adult life that are a continuation of the normal developmental pattern. Some of them represent further physical growth at a time when it was once thought that no further increase in skeletal dimensions occurred. Others are further steps along the path of development that we have followed in childhood and adolescence which lead to the changes we refer to (not very positively) as aging. But you’ll experience aging, and you need to know how it affects the patients you will be treating.

In addition to viewing this program, read pages 104-113 (5th ed) or 119-128 (4th ed) in Contemporary Orthodontics, and take the self-test at the end of this module.

Learning Objectives

After viewing this program, you should be able to:

Section 1 – describe the timing and pattern of skeletal growth in adults

Section 2 – describe the facial soft tissue changes that accompany aging and discuss their clinical significance

Section 3 – describe maturational and aging changes in the dentition, including normal patterns of attrition and abrasion, as well as alterations in pulp chambers and vascularity

Section 4 – discuss the possibilities for crowding of lower incisors in late adolescence and early adult life, and indicate which possibility is the most likely cause

Skeletal Growth in Adults

Weight Change in Adult Life

Obesity, of course, is now a public health concern of considerable magnitude. On the other hand, just about everyone gains weight between ages 20 and 50. A recent report showed that on the average, a college graduate can be expected to gain 40 pounds before the 25th anniversary of graduation. Some, of course, will gain a lot more than that, but it simply isn’t true that growth in the context of weight gain ends as one enters adult life.

Height Changes in Adult Life

Does an increase in height occur in adult life? Interestingly, the answer is no, and you already know why—don’t you?

That’s right, once the epiphyseal plates of the long bones have been bridged by bone, which normally occurs at the end of adolescence, any further increase in the length of these bones would have to be due to surface changes in the joints.

In fact, beyond age 50 most individuals experience a decrease in height of an inch or two, as intervertebral discs become compressed. It’s probably true that the more weight you gain, the more height you’re likely to lose for this reason.

That doesn’t mean, however, that all the epiphyseal plates close at the same time. The small bones of the hands and feet, especially the phalanges and tarsals, still can have endochondral growth into the early 20s, and growth of the cartilaginous nasal septum is possible for a long time because this cartilage persists indefinitely. Also, bones that do not depend on growth of cartilage would be capable of growth, no matter what happened to growth cartilages. The mandible is the best example of a bone like that. It’s not surprising, therefore, that hands, feet and lower jaws are likely to grow at least a little after growth in height is completed. The nose, as we will see, can grow a lot.

Changes in Facial Dimensions in Adults

The amount of facial growth that occurs beyond the early 20s was not appreciated until Behrents in the 1980s succeeded in recalling a number of individuals whose facial growth had been studied with serial cephalometric radiographs in the Bolton Growth Study in the 1930s, 1940s and early 1950s. Behrents was able to get follow-up cephalograms forty to fifty years after the last recall for this growth study, when the subjects were in their 30s.

Superimposition on the cranial base showed that the same pattern of downward-forward growth of the jaws that occurred in adolescence continued, albeit very slowly, until quite late in life. Although the amount of growth in each year was small, over decades it added up to noticeable amounts.

In the woman shown here, the black tracing is from age 34, and the red one is from age 83. Her facial growth changes over a this period of nearly 50 years were reasonably typical of what was observed:

• both the maxilla and mandible grew forward, in her case a little over 2 mm
• the ramus lengthened a couple of millimeters, reflecting further growth of the muscles of the pterygoid sling (masseter and internal pterygoid)
• the teeth in both jaws were carried forward by the late jaw growth
• the nose grew nearly twice as much as the jaws.

Changes in Facial Dimensions in Adults: Pattern Constancy

Note the changes in this man from age 37 to 77. He had been treated orthodontically for a Class II malocclusion, the orthodontic description of the condition in which the upper teeth protrude. This usually is due to deficient growth of the mandible. In his case, the same pattern of growth that led to his Class II problem as a youth continued late into adult life. His maxilla grew forward more than his mandible, and the maxillary incisors were carried forward more than his mandibular incisors.

The result, of course, was a partial return of the condition for which he had been treated successfully many years previously. Is this relapse? In one sense it is—the teeth returned toward their pretreatment relationship. In another sense it isn’t, because what really happened was growth long after treatment that tended to recreate the original dental relationship. He didn’t simply slip back toward the original dental problem.

If it’s not relapse what is it? Lapse? That’s not a commonly used term, so we can laugh when it’s used this way—but a return toward a previous dental and jaw relationship because of late disproportionate growth isn’t like relapse in the usual sense of going back to the original situation.

Changes in Facial Dimensions in Adults: Dento-alveolar Changes

It is possible to superimpose on the bony structures of the maxilla and mandible, in order to get a closer look at the changes in the shape and size of the bones, and in the changes of the dentition relative to its bony base.

These superimpositions, showing the mean changes in Behrents’ sample of individuals who were recalled after >30 years, make it clear that the pattern of change in adult life is very similar to what occurred during growth in adolescence. From one year to the next there is very little change, but over decades changes can and do occur.

We really can’t say that growth stops in late adolescence. Instead, it declines to the slow rate that is characteristic of adults, and continues at that slow rate beyond age 50.

Facial Soft Tissue Changes with Aging

Characteristics of Facial Soft Tissue Changes

With increasing age, we have seen that surprisingly large changes occur in the hard tissues of the face—but changes in the facial soft tissues are greater than the hard tissue change, and a dentist must understand them to offer the best care to older patients.

The soft tissue changes can be put into 3 categories:

1. decrease in lip fullness
2. downward movement of the lips relative to the teeth, leading to less display of the maxillary incisors and greater display of the mandibular incisors
3. deepening of skin folds and loss of skin tone

Let’s look at these in turn.

Decrease in Lip Fullness

As males or females get older, not only does lip fullness decrease, the amount of lip vermilion also decreases (image 1). One of the ways you have learned to judge the age of the individual you just met is to assess the lip contours. You can imagine that dentists would have to be careful with treatment that decreased the amount of tooth support for the lips and accentuated the lip changes.

Fortunately, for most people the lip changes are not a problem and are accepted as just part of life. If it is a problem for someone who is fighting aging, plastic surgeons can thread denatured collagen matrix (Alloderm) into the lips to provide a more subtle and longer lasting increase in fullness (images 2 and 3) than is achieved with collagen implants. This material is soft, so after treatment it wouldn’t be like kissing a rope.

Image 1: Lip contours at age (left), age (center) and age 70 (right)	Image 2: Alloderm lip augmentation, step 1
Image 3: Alloderm lip augmentation, step 2

Decrease in Lip Fullness (cont.)

There is an adolescent spurt of growth in the lips, especially in girls, and lip fullness increases up to about age 16—and then begins to decline, to the point that some young women are troubled by this in their early 20s and want to do something about it. This advertisement, which appeared in a magazine (and probably elsewhere) not long ago, states it quite clearly: “full lips … are associated with beauty and youth.”

Downward Movement of the Lips

After adolescence, the lips tend to move downward relative to the teeth so that maxillary incisor exposure at rest and on smile decreases, while the lower incisors increasingly are exposed. The change can be seen between adolescence and the mid-20s (image 1) and between that time and middle age (image 2). It can make quite a difference in facial appearance. In fact, incisor exposure is one of the things that people judge when evaluating how old someone is.

Image 1: Maxillary incisor exposure at age 15 (left) and age 25	Image 2: Exposure of upper and lower incisors at age 30 (left) and age 50

Incisor Display as a Function of Age

This graph shows the amount of upper and lower incisor display at rest as a function of age, from a cross-sectional study published in the prosthodontic literature.

Note that below age 30, there is almost no display of the lower incisor at rest but >3 mm display of the upper incisor. By age 50, there is considerably more display of the lower than the upper incisor, and beyond age 60 the average individual has no display of the upper incisor and >3 mm display of the lower incisor.

Keep in mind that the chart does not show the considerable individual variation that exists. Nevertheless, it is obvious that more display of your lower than your upper incisors, at rest or when you smile, makes you look older. In orthodontic or prosthodontic treatment, positioning the incisors relative to the lips is a critical part of obtaining an esthetic result. You’ll rarely be thanked for making your patients look older.

Skin Folds and Tone

Typical soft tissue changes with increasing age include

• slight jowling (droop of the cheeks) as skin tone declines (skin becomes less elastic)
• submental fat deposition (under the chin)
• deepening of the paranasal skin folds, and
• droop of the commisures (outer ends) of the lips.

The left image shows this woman at age 25, the right one at age 40. The changes are subtle but noticeable, and will become more apparent as she gets older.

Skin Folds and Tone (cont.)

In plastic surgery the classic “face lift” approach was to pull the skin tighter to decrease the folds and wrinkles. In recent years it has been acknowledged that a more natural appearance is obtained by “filling up the bag”, increasing the amount of hard tissue support for the overlying soft tissues. This can be done to some extent by orthodontic or prosthodontic treatment (images 1 and 2), and to a greater extent by surgical repositioning of the jaws (image 3).

For the patient in late middle age who is seen in images 1 and 2, fracture of the crown of a lower incisor was a problem for two reasons. Not only was the rough edge of the tooth irritating to the tongue and lip, the broken tooth was clearly apparent when she smiled. When lower incisors are crowded in adult life and something happens to one of them, extracting the damaged tooth and closing the space orthodontically can be a good plan. For this patient, however, that would have decreased lip support, so a better plan was to align both the upper and lower incisors, moving them forward and increasing lip support, and then restore the fractured incisor. She appreciated looking a bit younger rather than older after treatment.

For the patient in image 3, who had always had less support for her facial soft tissues than ideal, a dramatic improvement in facial soft tissue appearance was created by surgery to move her maxilla forward. For her, the problem was lack of bony support for the soft tissues, and tightening up the skin would not have produced nearly as favorable a change.

Image 1, Before orthodontic treatment: The fractured lower incisor was a problem for two reasons: it irritated the lip and was apparent on smile.	Image 2, After orthodontic treatment: Aligning the incisors by tipping them facially has increased lip support and facilitated restoration of the fractured tooth.
Image 3, Before and after orthognathic surgery to advance the maxilla: Note that advancing the maxilla tightened her skin and decreased the paranasal folds, giving her a more youthful appearance as well as better dental occlusion.

Changes in the Teeth and Supporting Structures

Aging Changes in the Teeth: Wear and Attrition

Aging changes in the teeth happen in two major ways: wearing away of the enamel surfaces and decrease in the size of the pulp chamber.

Extensive wear of tooth surfaces was common among humans until quite recently, because a primitive diet included harder and more abrasive materials than the modern soft diet. It is instructive to look at Australian aboriginal skull specimens from the 19th century to see the progressive and extensive wearing away of the teeth that occurred.

Image 1 shows the mandible of a child of approximately age 8. Note that wear of the occlusal surfaces of the first molars already exists, although these teeth have only been in the mouth for a couple of years. By dental age 14 (image 2), wear has penetrated through the enamel on the occlusal surface of the first molars and extensive wear exists on the incisors. In an adult of indeterminate age, enamel is gone and dentin is being worn away on the surface of all teeth except the 3rd molars, and enamel has been penetrated on these teeth.

Image 1: Australian aboriginal child approximately age 8	Image 2: Australian aboriginal youth approximately age 14
Image 3: Australian aboriginal adult, indeterminate age

Aging Changes in the Teeth: Wear and Attrition (cont.)

A lateral view of maxillary and mandibular teeth in occlusion, from the collection of aboriginal skulls, shows how the cusps of the teeth have been worn away so that a flat plane occlusion exists.

It also shows that there is wear of the interproximal surfaces as well as the occlusal surfaces of the teeth. This occurs as the teeth rock back and forth relative to each other under the stress of heavy occlusal forces, which were necessary when none of the food had been cooked. With increasing age, the tooth loses both crown height and width.

Aging Changes in the Dental Pulp

Given the amount of wear on the teeth that you just observed, you could ask at what point pulp exposure occurs and the tooth is lost. The answer is that this is possible but rarely occurs. Why not? Because with increasing age the size of the pulp chamber decreases as new dentin is formed, and this process accelerates in teeth that are being worn away.

Note the reduction in the size of the pulp chambers, especially of the molars, in this typical modern individual who does not have extensive wear of the teeth. The upper radiograph was taken at age 16, the lower one at age 26. This process of gradually filling in the pulp chamber continues throughout adult life, but proceeds less rapidly as you get older—unless there is severe wear of the teeth.

Now that the teeth don’t wear down as they once did, this protective mechanism is less important, but it still occurs—and makes it easier to restore teeth in older individuals. The dentist doesn’t have to worry so much about a pulp exposures when the tooth is being prepared.

Exposure of the Crowns of the Teeth: Gingival Recession?

As teeth erupt, it is apparent that more of the crown is exposed beyond the gingiva. This continues after teeth have come into occlusion, as in the girl shown here. At age 10, only a part of the crowns of her maxillary incisors were exposed. At age 16, almost all the crown of each incisor is exposed, and the gingiva appears to have retracted.

At one time it was thought that this occurred primarily by “passive eruption”, which was not eruption at all but recession of the gingiva. There is no doubt that the gingiva retracts relative to the crown during adolescent growth. There is considerable doubt, however, that this really is gingival retraction. Instead, the tooth continues to erupt, and the gingiva remains about where it was. Note the increase in face height that occurred for this patient during the time that the incisors were increasingly exposed. The teeth had to erupt to stay in occlusion as the lower jaw grew downward away from the upper jaw. All that is necessary to create the appearance of gingival retraction is for the supporting structures of the teeth not to grow quite as much as the teeth erupt. Passive eruption, in short, is not nearly as important as active eruption in increasing the amount of the crown that is exposed.

Image 1: Exposure of the clinical crowns of maxillary incisors at age 10 and 16	Image 2: Smile photos at age 10 and 16. Note the increase in face height that required further eruption of the teeth.

Exposure of the Crowns of the Teeth: Gingival Recession?

The concept that retraction of the gingiva is part of normal development is important when aging is considered, because at one time it also was thought that gingival recession normally continued as patients got older.

In fact, in adults gingival recession (image 1) is an indication of pathology, not an inevitable part of getting older. If you take care of your teeth and the periodontal tissues remain healthy (image 2), gingival recession doesn’t occur during aging. If you develop periodontal disease, it does. Gingival recession isn’t a part of the normal aging process.

Knowing that retraction of the gingiva is not part of normal development is important when aging is considered, because at one time dentists thought that gingival recession normally continued as patients got older, and considered it just a part of the normal aging process. Now we know that it’s a sign of disease or trauma.

Image 1, Gingival recession in an adult: Recession is the result of poor periodontal health, not a normal consequence of growth and aging.	Image 2, A healthy adult dentition: Greater exposure of the crowns, up to but not beyond the crown-root interface, is largely due to eruption in response to vertical jaw growth that leaves the gingiva behind.

Late Lower Incisor Crowding: Why?

Prevalence of Lower Incisor Crowding by Age

It is a frequent observation that lower incisors become more crowded after adolescence. Quite typically, lower incisors that were nicely aligned at age 15 or 16 become slightly (sometimes more than slightly) crowded and irregular by the early 20s. Those that were mildly or moderately irregular get worse, as this graph from American epidemiologic data shows. Did that happen to you?

This is frustrating for orthodontists, of course, because it is so difficult to keep lower incisors perfectly aligned after braces are removed during adolescence. But late crowding of these teeth occurs whether or not they had been aligned orthodontically. Why does this happen?

Late Incisor Crowding: Third Molars?

Lots of people in the general population are sure that third molars cause the late incisor crowding. It makes sense because of the timing: the crowding develops about the time the third molars are erupting, or should erupt but can’t because there’s no room for them. It also makes sense because it seems reasonable that the third molars could exert pressure against the other teeth as they try to wedge their way into the dental arch. When you see an impacted third molar on a panoramic radiograph, you can picture how it would be pressing against the other teeth.

For many years, dentists encouraged patients to believe that the third molars caused crowded incisors. So, when Susie’s incisors begin to crowd while she’s off in college, her grandmother is very likely to tell her that her third molars are the problem. The orthodontist often listens to former patients say “I know I should have gotten my third molars out, but I didn’t get around to it—and now look at my teeth”. It’s easy for the doctor to agree with that even if he or she is wondering if it’s correct.

Problems with the 3rd Molar Theory

The theory that third molars are the cause of the late incisor crowding has two big problems:

1. Lower incisor crowding develops in people whose third molars are congenitally missing, at about the same level of prevalence as in those with third molars. For the patient shown in this radiograph, the lower incisors became quite crowded during his late teens, but third molars couldn’t have been the cause because he didn’t have any.

2. Numerous studies of the relationship between third molar presence, position, or other characteristics have reported little or no correlation with incisor crowding. If the third molars have a role in the development of incisor crowding, it’s clear that it isn’t a major one.

When you think about it, it’s a bit hard to see how the third molar could win a contest against all the rest of the teeth. One little tooth at the back of the dental arch pushes all the rest of them around? Powerful tooth indeed if it can do that!

Late Incisor Crowding: Interproximal Wear of Teeth?

A second theory, which offers an explanation for crowding more generally, but also relates to late incisor crowding, was based on the aboriginal skeletal material that we’ve already looked at. Raymond Begg, an influential Australian orthodontist of the mid-20th century who collected aboriginal skeletal remains, noted that the Australian aboriginals had (and have) remarkably well-aligned teeth. They do not develop late incisor crowding, while their fellow citizens of European descent often have both incisor crowding and impaction of third molars.

Begg came to believe that interproximal wear of the teeth was necessary to provide enough space in the dental arch for all the permanent teeth, and that this was the key to the excellent alignment of teeth in the aboriginal population. He suggested that extraction of first premolars, to provide the space that wasn’t being produced by attrition of the other posterior teeth, was necessary in most people to obtain good dental alignment now that almost everyone is on a relatively soft diet.

Would interproximal wear in the aboriginal group but not in the European group really explain the difference in dental crowding?

Problems with Begg’s Theory

The interproximal wear theory also has a major problem: modern Australian aboriginals have a diet very different from that of their ancestors, and quite similar to the European soft diet. Yet these modern aboriginals who did not experience interproximal wear as they were growing up don’t develop incisor crowding.

This dissected skull, showing the dentition in a young adult who has some wear on the teeth but not a lot, is from an unknown source and probably is not a modern Australian aboriginal. But both the minimal wear on the teeth (note how little loss of the width of teeth has occurred) and the excellent alignment are typical of Australian aboriginals now.

In the aboriginal population, the primary effect of the dietary change has been to greatly increase the prevalence of periodontal disease, not to produce crowding of the teeth. The significant difference between the European-derived and aboriginal populations turns out to be a shorter neck and higher tongue position in the aboriginals, and a wider face. As you will learn in the teaching module on equilibrium effects, resting pressures by the tongue and lips/cheeks against the teeth are a major determinant of dental arch dimensions and the position of the teeth.

Late Incisor Crowding: Late Mandibular Growth?

We have noted already that a small increment of mandibular growth often occurs after growth of the other facial structures has declined to the very slow adult growth rate. Could this be related to late incisor crowding?

The answer is yes. How it happens can be understood best by looking at what happens to lower incisors in patients with excessive mandibular growth. In a typical patient with this growth pattern (images 1 and 2), superimposition of serial cephalometric radiographs shows that as the mandible grows forward, the incisors are tipped lingually and forced into a more upright position as lip pressure against them increases. The effect is to shorten arch length, and this leads to crowding of the incisors.

In almost everyone, the mandible grows forward a little relative to the maxilla in the late teens or early 20s. As this happens, the lower incisors tip lingually and crowding develops. Both x-rays and clinical examination show that backward movement of the incisors relative to the chin, not forward movement of the posterior teeth, almost always is what happens as late crowding develops.

To put it in terms we’ve used before: the determinant of late lower incisor crowding is the small amount of mandibular growth that usually occurs at that time; the mechanism is lip pressure against the incisors.

Image 1: Cephalometric superimpositions, excessive mandibular growth. Note the lingual tipping of the mandibular incisors as the mandible grew forward.	Image 2: By the end of adolescence, the upright position of the incisors was apparent, and incisor crowding was developing.

Late Incisor Crowding: Summary

For late lower incisor crowding, late mandibular growth explains almost all of what happens. It seems clear that lack of wear on the teeth has little or nothing to do with it.

Is it possible that pressure from third molars that are trying to erupt contributes to crowding? Perhaps the third molars sometimes are “the straw that broke the camel’s back”, but their influence is minimal compared to mandibular growth.

Maturational Changes: Summary

Important points to remember about maturational changes:

Facial growth continues, very slowly, at least into the 50s and perhaps beyond:

• the nose grows more than anything else
• for most people, there’s a little more mandibular than maxillary growth
• the original growth pattern is followed, so a partial re-creation of a jaw relationship corrected by orthodontic treatment may occur many years afterward

Facial soft tissue changes:

• decrease in skin tone (less elasticity), which causes wrinkles
• deepening of facial folds, especially the nasolabial fold
• downward movement of the lips → more display of lower incisors, less display of upper incisors

Dental changes:

• enamel wear (but much less with modern soft diet than previously)
• decrease in size of pulp chambers

Crowding of lower incisors in late teens / early 20s:

• mostly due to differerntial forward growth of mandible at that time
• as this growth occurs, lower incisors tip lingually in response to lip pressure against them
• third molars play a minor, if any, role in producing incisor crowding

Self-Test Referral

Now, before you take the self-test in the following section, be sure you have read pages 104-113 (5th ed) or 119-128 (4th ed)in *Contemporary Orthodontics.*Then use the self-test to be sure you understand the important points you learned in this module.

Self-Test

Question 1

Which of the following signals the end of growth in height?

1. closure of epiphyseal plates of femur and tibia ✓
2. closure of epiphyseal plates of humerus and radius
3. fusion of cervical vertebrae
4. all three are equally important

Correct

That’s correct. The long bones of the legs can’t grow significantly longer after their epiphyseal plates close.

Incorrect

No, that’s incorrect. The long bones of the legs can’t grow significantly longer after their epiphyseal plates close. The arms can’t grow longer after their epiphyseal plates close, but this has no influence on height. Cervical vertebrae, fortunately for those who want to move their neck, don’t fuse.

Question 2

One of your 55-year-old patients commented that he used to be 6 feet tall, but now he’s only 5”11”. What would you think was the most likely cause?

1. resorption of bone in the hips
2. resorption of bone in the knees
3. curvature of the cervical spine
4. compression of cervical vertebrae
5. compression of intervertebral discs ✓

Correct

That’s right, aging men and women are likely to notice a loss of one or two inches in height, and the usual cause is compression of intervertebral discs. Resorption of bone in hip or knee joints is unlikely to lead to noticeable height loss, and vertebrae don’t get compressed (in the absence of severe trauma). Spinal curvature is a possible but unlikely cause of height loss.

Incorrect

No, that’s wrong. Aging men and women are likely to notice a loss of one or two inches in height, and the usual cause is compression of intervertebral discs. Resorption of bone in hip or knee joints is unlikely to lead to noticeable height loss, and vertebrae don’t get compressed (in the absence of severe trauma). Spinal curvature is a possible but unlikely cause of height loss.

Question 3

Which of the following is not associated with increasing age?

1. 1-2 mm forward growth of the mandible
2. 1-2 mm lengthening of the mandibular ramus
3. widening of the nose
4. decreased prominence of the nasal tip ✓
5. increased prominence of the nasolabial fold

Correct

That’s right. With increasing age the nose almost always becomes more, not less prominent. It widens as well as growing forward and downward, and the nasolabial fold (the vertical fold along the sides of the nose) deepens. Slow forward growth of the mandible and lengthening of the ramus also usually occur.

Incorrect

No. you’re wrong. With increasing age the nose almost always becomes more, not less prominent. It widens as well as growing forward and downward, and the nasolabial fold (the vertical fold along the sides of the nose) deepens. Slow forward growth of the mandible and lengthening of the ramus also usually occur.

Question 4

(A) In patients who have been treated orthodontically for a skeletal problem like a deficient mandible, some return of the original condition is likely long after treatment was completed because (B) the slow growth that occurs in adults tends to be in the same pattern that produced the skeletal problem initially.

1. A true, B true, A and B related ✓
2. A true, B true, A and B not related
3. A true, B false
4. A false, B true
5. A and B false

Correct

That’s right. The two statements are true and related. Even though facial growth during adult life is very slow, if the upper jaw grows more than the lower jaw, there will be a partial return of the original jaw relationship in a patient previously treated to correct mandibular deficiency—and that pattern of growth is likely in a patient who had deficient mandibular growth in childhood and adolescence.

Incorrect

No, that’s wrong. The two statements are true and related. Even though facial growth during adult life is very slow, if the upper jaw grows more than the lower jaw, there will be a partial return of the original jaw relationship in a patient previously treated to correct mandibular deficiency—and that pattern of growth is likely in a patient who had deficient mandibular growth in childhood and adolescence.

Question 5

Which of the following are typical aging changes in the facial soft tissues?

a) flattening of the nasolabial fold

b) widening of the vermilion border of the lip

c) increased display of the upper incisors

d) increasing tightness of the cheeks

1. a only
2. b only
3. c and d
4. all the above
5. none of the above ✓

Correct

That’s right, none of these changes occur in typical aging of facial soft tissues. The nasolabial folds deepen rather than flattening, the vermilion border of the lip narrows instead of widening, there is less display of the upper incisors, and the cheeks become looser rather than tighter.

Incorrect

No, that’s wrong. None of these changes occur in typical aging of facial soft tissues. The nasolabial folds deepen rather than flattening, the vermilion border of the lip narrows instead of widening, there is less display of the upper incisors, and the cheeks become looser rather than tighter.

Question 6

(A) Girls may become concerned about the fullness of their lips in their 20s because (B) lip growth may continue beyond adolescence and eventually lead to a need for lip reduction.

1. A true, B true, A and B related
2. A true, B true, A and B not related
3. A true, B false ✓
4. A false, B true
5. A and B false

Correct

That’s correct, the first statement is true but the second one is false. Lip fullness is maximal at about age 16, and decreases after that. If a girl is concerned about lip fullness in her 20s, almost always it’s concern about loss of fullness, not excessive fullness.

Incorrect

That’s wrong. The first statement is true but the second one is false. Lip fullness is maximal at about age 16, and decreases after that because further lip growth does not occur. If a girl is concerned about lip fullness in her 20s, almost always it’s concern about loss of fullness, not excessive fullness.

Question 7

Relative to the upper incisors, which movements are characteristic of aging lips?

1. forward

2. upward

3. backward

4. downward

1. 1 and 2
2. 1 and 4
3. 2 and 3
4. 3 and 4 ✓

Correct

That’s right, relative to the teeth the lips move backward (closer to the teeth as the lip becomes thinner) and downward (as the facial soft tissues loosen and sag down relative to all the hard tissues of the face).

Incorrect

No, that’s wrong. Relative to the teeth the lips move backward (closer to the teeth as the lip becomes thinner) and downward (as the facial soft tissues loosen and sag down relative to all the hard tissues of the face).

Question 8

On the average, how much of the upper incisor is displayed when the lips are at rest in a patient who is over age 60?

1. none, the lower incisors show but the uppers don’t ✓
2. 1 mm
3. 2 mm
4. 3 mm
5. 4 mm or more

Correct

That’s right, by age 60 the upper incisors are not visible when the lips are at rest, while on average the lower incisors have about 3 mm exposure.

Incorrect

No, that’s incorrect. The amount of display of the upper incisors decreases steadily with increasing age, and by age 60 the upper incisors are not visible when the lips are at rest. By then, on average the lower incisors have about 3 mm exposure.

Question 9

For best facial appearance in a normal adult, which of the following would be the most desirable change in the position of the incisors relative to the upper lip during orthodontic treatment or prosthodontic replacement?

(1) upper and lower incisors down

(2) upper and lower incisors forward

(3) upper and lower incisors up

(4) upper and lower incisors back

1. 1 only
2. 2 only
3. 1 and 2 ✓
4. 1 and 4

Correct

That’s right, bringing the incisors forward provides more lip support and contributes to “filling up the bag”. Moving them down improves the visibility of the upper incisors and provides a more youthful appearance. For most patients, backward and upward movement would make the patient look older.

Incorrect

No, that’s wrong. Bringing the incisors forward provides more lip support and contributes to “filling up the bag”. Moving them down improves the visibility of the upper incisors and provides a more youthful appearance. For most patients, backward and upward movement would make the patient look older.

Question 10

By what age would you expect to see wear on permanent teeth in a patient on a primitive hard / abrasive diet?

1. age 8 ✓
2. 10
3. 12
4. 16
5. 20

Correct

That’s correct. Wear would be noted on the permanent teeth within 2 years of the time they erupted, so already at age 8 the first permanent molars and probably the incisors would show wear.

Incorrect

That’s wrong. Wear would be noted on the permanent teeth within 2 years of the time they erupted, so already at age 8 the first permanent molars and probably the incisors would show wear.

Question 11

Aging changes in the dental pulp typically make the pulp chamber:

1. shorter and wider
2. shorter and narrower ✓
3. longer and wider
4. longer and narrower

Correct

That’s right. As you get older, the pulp chamber typically becomes narrower as dentin fills in the sides, and shorter as dentin is added across the upper part of the chamber.

Incorrect

That’s wrong. As you get older, the pulp chamber typically becomes narrower as dentin fills in the sides, and shorter as dentin is added across the upper part of the chamber.

Question 12

(A) Lengthening of the clinical crown of teeth usually occurs by passive eruption because (B) retraction of the gingiva is necessary to completely expose the clinical crown.

1. A true, B true, A and B related
2. A true, B true, A and B not related
3. A true, B false
4. A false, B true
5. A and B false ✓

Correct

That’s correct. Both statements are false. Retraction of the gingiva in children and adolescents, which is described as passive eruption, usually is less important in obtaining exposure of the clinical crown than active eruption in concert with vertical growth of the jaws.

Incorrect

No, that’s wrong. Both statements are false. Retraction of the gingiva in children and adolescents, which is described as passive eruption, usually is less important in obtaining exposure of the clinical crown than active eruption in concert with vertical growth of the jaws.

Question 13

What is the best description of the relationship between 3rd molar eruption or impaction and late crowding of lower incisors?

1. almost always 3rd molars are the cause of late incisor crowding
2. often but not always 3rd molars are to blame
3. perhaps a little effect from 3rd molars but not the major cause ✓
4. 3rd molars are too far away to have any effect on incisor position

Correct

That’s right. Several lines of evidence indicate that 3rd molars are not a major contributor to incisor crowding, but some studies suggest that they may be a minor contributor.

Incorrect

No, that’s incorrect. Several lines of evidence indicate that 3rd molars are not a major contributor to incisor crowding, but some studies suggest that they may be a minor contributor.

Question 14

(A) Late crowding of lower incisors usually accompanies late forward growth of the mandible because (B) the forward growth increases tongue pressure on the incisors and tips them facially.

1. A true, B true, A and B related
2. A true, B true, A and B not related
3. A true, B false ✓
4. A false, B true
5. A and B false

Correct

That’s right, the first statement is true and the second one is false. Late crowding of lower incisors accompanies forward growth of the mandible because the growth increases lip pressure that tips the incisors lingually, shortening arch perimeter and causing crowding.

Incorrect

No, that’s wrong. The first statement is true and the second one is false. Late crowding of lower incisors accompanies forward growth of the mandible because the growth increases lip pressure that tips the incisors lingually, shortening arch perimeter and causing crowding.