Transcribed by Matt Asaro April 15, 2014

Craniofacial Biology – [General Concepts of Growth II and III] by [Dr. Forsea]

[1]- [Outline of Our Two Days] [Dr. Forsea]- How is the mandible displaced? Downward and forward? Due to what? Anyone want to give it a go? Uh huh. (Student answers) Mhm, that’s one, so what’s primary displacement that’s secondary very good do you know by any chance primary displacement? (Student answers) That’s right that’s good that’s primary displacement it’s growing I length in the posterior region and as it’s doing that its growing against the cranial length of fossa and as its doing that its pushing the jaw forward. Does bone resorption occur on the oral cortical surface of the maxilla? Think of your V principle. Does bone resorption occur on the cortical oral surface of the maxilla? Yes or no? No, that is the area of bone deposition. You’re thinking of your V. It’s the upside down V actually, maybe a little bit of the U in the maxilla’s case. Deposition it he bottom portion and resorption on the top portion. Alright just a couple more questions. Okay, we touched upon this a little bit yesterday what is the most stable region of the craniofacial complex, Yup, the cranial base that’s the most stable region of the craniofacial complex. Oh and this is important. What are the five principles of bone growth mechanisms? Remember we had a list of the five bone growth principles. (endosteal/periosteal cortical drift, relocation and remodeling, displacement, and “V principle”) Yes that’s right. And if you’re thinking of cortical drift and cortical drift theory, in what instance would cortical bone reduce in size as opposed to staying the same or accentuating in size? In what instance do you find that the cortical bone will reduce in size? (Student answers: Resorption) Mhm. If you’ll remember that slide we had that drifted the bone off to the right if you resorb more than you depose you’re gonna end up with the thinner cortical plate, okay? What is a reversal line? Do you guys remember that? (Student answers) Yup, correct. That’s the line where they meet where resorption and deposition meet. So here’s the last one and then we’ll go to todays lecture. According to the V principle of bone formation, does bone formation occur on the anterior surface of the mandible at the level of the alveolar bone? Yes or no? Resorption, Yes, yes it does, correct. Okay so very quickly I’m just going to recapitulate quickly the definition of physical growth which is the outcome of the interaction between genetically controlled cell proliferation which is hypertrophy, hyperplasia, and inter cellular matrix, these three are really important to remember okay. And the environmental influences that modify this genetic programming, okay. Umm, the craniofacial complex is all growing at the same time and it’s ongoing structural and functional equilibrium as it happens at the same time. Alright, people that you should know and remember you might want to write this down if you’re taking notes. Dr. Bourke who is the professor in studying implants and superposition of cephalometric x rays. Dr. Moss right here from Columbia University who created the theory of the functional matrix theory and we’re going to talk about that today. Dr. Enlo who studied Growth and development for many years and one of the theories that he has come up with is the difference between the sites of growth and the centers of growth so those two things and translation and transformation of bone and finally then Lindberg, 1970’s, 1972, he kinda gave us our current theory of growth and development which is a combination of the ones prior tot hat and again we’re going to talk about that today.

Okay, going through our outline today we’re going to hit methods for studying growth and disease for growth peaks and maturation, variability in growth, and theories in craniofacial growth. I’m just going to skip out of this really quickly so we can go down.

[34]- [Methods for Studying Growth] Dr. Forsea - Alright so there are methods for studying growth. What are the methods for studying growth? Physical growth there are three basic methods. One is a measurement approach and under that category falls anthropometrics, craniometrics, and cephalometrics. There is the experimental approaches to studying growth and under that category falls vital staining’s, radioactive tracers, tetracycline staining’s, and implant radiology. Okay, and then of course we have the genetic influences on growth which is an up and coming field, epigenetics, it’s the study of how genes are modified and expressed based on our environmental surroundings. Okay, genetic mutations expressed can effect growth and development in significant ways and our future will probably test blood and saliva to see how a person will react the likelihood of poor or a well response to any orthodontic treatment. It’s actually pretty amazing. I saw an electron the other day in the future we will pretty much become obsolete robots will be doing everything.

Okay, Types of studies that can be done when we’re doing these measurements there are specific types of measurements that can be done. One is a longitudinal study, one is a cross sectional study, and one is a mixed longitudinal study.

[35]- Longitudinal StudiesDr. Forsea- What is a longitudinal study. A longitudinal study is studies of the same groups of children over a longer period of time. It is very valuable data collection bc it shows growth rates and variability of individual growth. It’s not easy to repeat this kind of study because it takes an exorbitantly long amount f time especially if you’re studying growth for 20 years of somebody’s life. By the time you’ve finished studying 20 years you’re ready to retire. Okay, and also a disadvantage to longitudinal studies is it’s very difficult to get your subjects to come back repetitively over a long period of time and it is a long time to collect data.

[36]- Cross-sectional studiesCross sectional studies, there are many different subjects that we work with in a cross sectional study. This is needed to minimize the effect of variation that exists in each individual which could influence the outcome results. The more numbers of subjects in a study the less likely that one persons exception or variability stands out or skews your results. We take measurements at different points in their life. We collect data for these points in time. Some of the advantages are that we accumulate data very quickly. Such a study as a cross sectional study could give the average rate of the growth for a population. Some of the disadvantages are variation of individuals could influence the outcome which we just talked about which is why we needed a larger subject size. And the standards of rate or velocity of growth can only be derived from longitudinal studies. By following each over a longer period of time.

[37]- Mixed Longitudinal Studies Mixed longitudinal studies are a combination of the cross sectional and the longitudinal types. They get the best of both worlds if you will. Examples are subjects of diff ages that are examined for a short period of time. So we can condense 20 years of studies in 6 years of less. For example you have one group that you’re studying from birth to six years. The six year study is ongoing, birth to six. The second group is from 5 to 11 years, the third group is from 10 to 16 and you have a fourth group from 15-21 years and rather than gathering this data for 21 years, you do it in six year time intervals but you’re studying four different groups at a time. You gather the data at the end of the six years, the span is from birth to 21 years. We’re doing a lot of these types of studies on theories of growth, on animal studies, why do we do a lot of animal studies? Does anybody know why we use a lot of animals in our studies? Yeah, and is it comparable to us as humans? Very much so because from a genetic point of view we are about 99% equal to that of a mouse, so all of the findings we get are faster, less expensive, we can sacrifice the animals unfortunately we have to sacrifice them sometimes but the relevancy is there since the genome is amazingly similar.

[38]- Methods for Studying GrowthWhat in fact are we measuring? What are we in fact measuring? We are measuring anthropometry, craniometry, and cephalometrics and lets talk about each in part a little bit.

[39] AnthropometryWhat is anthropometry? Anthropometry is the soft tissue measurements made on living individuals using underlying hard tissue landmarks. Soft tissue measurements made on living individuals using underlying hard tissue landmarks. We can do longitudinal and cross sectional studies with anthropometry. Craniometry is the precise measurements made on dry skulls, deceased individuals that allow study of growth patterns of extinct non living populations, cross sectional studies are the only type we can do on craniometry.

[40] Cephalometric RadiologyThe next studies are very up to date and very frequently used in our offices now. Why do orthodontists take cephalometrics radiologies, does anybody know? We’re looking at growth patterns, we’re looking at potential growth in the future. We’re looking at asymmetries, we’re looking at soft vs. hard tissue proportions, we’re looking at potential future growth, examining the root angulations of the anterior teeth and it helps our entire treatment plan based not on the numbers per se but on the whole story that the cephalometrics x ray tells you. It is a very precise oriented x ray. You have to have it replicated in order to gather the info you’re looking for. We need control of radiographic magnifications and it’s great when you’re doing this study to use the same cephalometrics x ray and not move it around. Not move the settings around. It allows direct measures of bony skeletal dimensions. It produces a two D replication of a 3D structure. This is really the only disadvantage that we have to cephalometric radiology is its in 2 D and we are treating a 3d person. We try to recumb this 2d scenario by taking up periapical and a lateral cephalometrics essay. You get more information that way

especially from an anterior posterior point of view. An anterior posterior point of view will give you asymmetries that are located in your patient. Main problem is again it’s only a 2D x ray in a 3D subject.

[41] Cephalometric RadiologyMore recently we’ve begun to use 3D imaging on our orthodontic diagnostic armamentarium. Does anybody know what kind of 3D imaging I’m talking about? Comb beam computerized tomography, MRI’s also, especially for TMJ’s. There is a controversy though, does the risk outweigh the benefit of using these 3D imaging on all our patients. I think that in the future depending on how things pan out we will probably be using a lot more 3D imaging in everything that we do in dentistry, definitely move away from cephalometrics, periapical, woops sorry I keep saying periapicals, I meant to say the anterior posteriors and go into complete 3D imaging.

[42,43] 3D CephalometryHas anyone seen a comb beam computer technology? This is kind of what they look like. This is one section and it is easier replicated and rotated and put upside down and you get a lot of information from it. Often used for dental impaction, airway obstructions, sinuses, tumors, mandibular functions, TMJ orientation, they’ve become overwhelmingly common for planning surgeries for patients with dentofacial deformities. The radiation exposure is only slightly higher than the cephalometrics x ray but when you put together radiation exposure for 3D image versus pan (can’t understand her) it probably evens out to be a bout the same. Positions in 3d imaging are a little difficult however new measurement techniques are evolving every day more recently we’re placing our implants in a position to superimpose. It will contribute in the future to significantly more growth and development knowledge I’m sure of that. MRI’s have no radiation, they are also 3D imagine and they’re great for TMJ analysis and results of a functional analysis and growth of the condyle.

[44] Cross Sectional vs. Longitudinal approachesThis is an important slide if you guys have it great if not you might want to write it down. In both anthropometrics and cephalometrics we can express cross sectional and longitudinal studies. In cross sectional studies it is of short duration to gather all the information vs. longitudinal studies it takes a lot longer. Variability in the sample can conceal certain details of your growth in the cross sectional study individual growth variations are seen due to timings in the longitudinal studies. We have a larger sample size that is necessary in the cross sectional studies. We have a smaller sample size in the longitudinal studies. The cross sectional allows estimation of average rate of growth of a population. Whereas the longitudinal study allows accurate predication of adult height Velocity of growth is ac ross sectional study growth curve. It is an incremental curve and it’s not sensitive to variation caused by timing. That’s the one good thing about a cross sectional study. When we’re looking at height, bone age occurrences of (?) in young girls, we can predict the height on the distance curve. A distance curve is a longitudinal study. Okay

[45] Graph Interpretation of Growth Data

How do we interpret the info that we gather? Okay. Growth Data are presented in graphic formats and allow easy understanding therefore there are two basic growth curves that we look at and use repetitively one is the distance curve which is a cumulative curve and a cross sectional format you can run into a school grab a couple nine and ten year olds, eleven year olds and you measure on a growth curve what their growth is in a short period of time ad you take one or two individuals and measure or plot over a long period of time. There is your growth curve okay. The velocity curve it shows a period of fast growth and a growth spurt. Okay. and this shows the rate at growth over a period of time showing increments of growth added each year so for example how much did you grow per year that’s the velocity curve.

[46] Examples of growth curvesOkay and here’s an example of both the growth and velocity curve. Which do you think is the growth or the distance curve? The distance not the growth curve. Is it he one coming up and own like this or the one gradually increasing in time? It’s actually the one that gradually increases in time so that’s your distance curve think of a long distance marathon. The velocity one is the one that goes up and down because your velocity changes during different periods of time so you grow more on year. Pre puberty you grow quiet a bit and you get that growth peak and then you go down. The velocity curve shows acceleration and deceleration in growth and when it occurs for a specific individual you note acceleration and velocity of growth at this particular person at 14 years of age. Um, in the adolescent period. So, we also note extremely good growth form birth to age 3 I had a question yesterday about cleft lip and plate and we have quite a bit of growth that takes place from growth to age 3 and that’s a good indication that is a good time to address these anomalies because molding of the bone can tae place well during those first three years of life. Um, Bone is very responsive to molding with things like plates and what we call NAMs (nasal alveolar molding device). Okay.

[47] Methods for Studying GrowthWe have different experimental approaches. This is our experimental approaches we have vital staining’s, we have radioactive tracers, and we have implant radiology. Vital staining’s are things such as a alizarin red and tetracycline staining’s. Implant radiology are the superb position of the implants that Professor Buerk did and radioactive tracers are tecniation that settles into the bone in certain periods of time and we can then notice them when we take an x ray.

[48] Vital StainingVital staining uses dyes that stain minimalized tissues. It was a very serendipitous finding about a well known British anatomist named John Hunter in the late 18th century and he noted that pigs that had been fed textile waste and retained the alazaran red within the textile waste when he sacrificed these pigs their bone retained in striated format bone deposition coloring of this textile alazaran red. When using the alazaran red he can determine many answers to growth formation in the bone. Very similar to what tetracycline does but we find that out by accident and here we have an example of a sacrificed rat that was done staining’s on him on a three week interval and you can see the growth rate of his condyle on those three week interval.

[49] Vital stainingthis is an another example of vital staining’s at one week intervals with different colorants to note where mineralization is occurring and what direction it is occurring and in this case it is going superiorly.

[50] Vital stainingTetracycline stain was an accidental finding in the fifties and sixties an unfortunate finding when it was often tetracycline I mean it was often the drug of choice used for upper respiratory tract infections and then when they developed we noticed that they left stains in certain periods of their development begin their teeth. The scars of those permanent teeth. Like I said it was an accidental finding. This young boy here who was treated at the age of around 2 to 2.5 with tetracycline ad you notice the developing perm ant tooth bud the staining measured right around the time the tooth bud was developing form that point forward.

[51] Radioactive TracersRadioactive tracers these are types of measurements that are used to determine whether a patient has stopped growing or not. They can be used as chronological age markers in series of sets and can often be used to determine if surgery can be had on a person or will we need to wait. I personally have never used radioactive tracers its not a common practice but in science we do use them. We use Technetium, with a normal distribution it occurs in the bone of the kidney. The bones and the bladder.

[52] Radioactive tracersAlright and I’m just going to go back really quickly because its says animals studies the radioactivity and localization is detected by autoradiography, does anybody know what autoradiography is? Alright, autoradiography is any technique used to produce the image of a 2D image of a radioactive substance.

[53] Implant radiologyImplant radiology is what we talked about a little earlier and Dr. Burek talked about this a little earlier and here you can see the implants placed there are relatively small and positioned in specific areas of the bone. And what he discovered is that everything is basically changed during bone growth and development. Remember the resorption and deposition animation we saw with the arrow yesterday. Everything is changing in different directions, all at the same time. Patients live with these forever. Once it is placed there were no repercussions it’s like having an implant placed into your mouth. This helps us to figure out something that was very important which was which structure is most stable which e talked about this at the beginning of the lecture. The craniofacial craniobase is the most stable complex and what we use now to superimpose are cephalometric x rays.

[53] Important Concepts in Studies of GrowthAn important concepts in the study of growth are patterns of growth, growth variability and timing of growth.

[54] Pattern of growthHere’s a pattern of growth. This is a schematic representation of the change of the overall body proportions. A two month fetus has about two thirds of its body head. A four month fetus about 25% of its body is the head, in an adult it’s about 1/8 that’s the proportions that grow with time. Complex proportions change during the normal growth and development. Cephalo-caudal gradient of growth is what we’re seeing here.

[55] The pattern of growthThis basically states that our bodies grow from head to toe which means our legs are longer than our arms our arms are longer than our necks and our mandible will grow for a longer period of time than the maxilla. The further you are from the head the longer time your bones will grow.

[56] AchondroplasiaWhen proportions do not grow correctly we see um, things such as achondroplasia which is a shortening of the length of the arms and one of the most common forms of dwarfism that exist today. What are some of the factors that influence proportional growth? Can anybody tell me some factors that you think might influence growth and development? What’s that? Growth factors, so hormonal influences, genetic factors, maybe some envt factors, disease can also influence the expression of genes. Right.

[57] Cephalocaudal gradient of GrowthOkay. Hence the downward and forward growth of our mandible and our maxilla with subsequent rotation of our mandible in the proper position because of our cephalo caudal gradient of growth. It applies to the cranial facial complex as well. It refers to an axis of increased growth extending form the head towards the feet it increase the height and the length of the mandible, the total vertical height of the facial features as well.

[58] Growth RatesGrowth rates this s an important charting. This is a Scammon’s growth curve and it’s often times used. For example, if we’re looking at this graph here and we’re looking at the lymphoid tissue and if this curve plots percentage of adult size over the years and the age so percentage of reaching adult size over adult age. If you’re looking at the lymph curve and that peak in the curve what does that say to you? As compared to the age of the child if you’re looking at that curve at about ten years old what happens to the lymph structures? They double in size and grow rapidly during that period they maximize and right after that peak after about 10,11 12 years old they start decreasing in size. Why is that important for us to know? Especially in orthodontics. Specifically related to the craniofacial complex the lymph structures are important in orthodontics because if a child ahs a breathing problem because of the adenoids or the tonsils the child can not breath well sot hey have a backwards and downward posturing of the mandible and if the posturing leads to an airway opening you’ll have pressure from the masseter muscles pushing on your maxilla. What is that going to do in terms of changing your overall growth and facial features? It’s going to narrow your maxilla, lengthen or elongate your facial features, you will at he same time posture your lower jaw downward and backward and possibly an open bite position and all of this due to your lymph being exacerbated

during a period of high growth. Okay if we go back tot eh Scammon curve we see the neural tissue is completed by the age of 6 or 7 we have general growth that accelerates at puberty similar to growth of the pediatricians growth chart. We have genital and sexual growth at that accelerates at puberty as well. If we look at our maxilla and mandible curve, the maxilla is similar to the neural cure and the mandibular curve is more similar to the general growth pattern. How does this chart affect orthodontics? It is essential for helping us understand when growth is approximately 100% completed to evaluate when we can treat a patient for a functional pliance therapy vs. when to treat a patient for surgery or camouflage therapy, moving he teeth around, The surrounding tissue affects growth and development of the craniofacial complex as we just spoke of. We can go back to our lymph structures and give us a very high mandibular pain structure with a vertically growing patient becomes much more difficult to treat (?)

[59-60] Growth variability All people are variable. Normal is a range, and ideal is the point so basically what we’re looking to see if somebody needs treatment and what we’re looking to treat that person to we’re looking at normal being a range a standard deviation from that ideal point. everybody can be your ideal typodont class 1 but we should look to get that that ideal pit within the range of normal. It is important to recognize abnormal or pathological growth. Very important to recognize this everyone is at a different level of the growth peak at different time so then there exists a lot of variation in the growth spurt and age. On a growth chart between 16-84 on the standard deviation is considered the normal range. Growth charts help to follow growth and development over time which is a longitudinal study. Growth variability occurs, this is just repeating, so much of variation in age because everyone at different level of the growth peak to tell if normal it’s deviations normal is around 16th and 84th again this is a little of a repeat. Growth charts help to follow growth and development over time. Growth charts can be used to follow a child over time to evaluate whether there is an expected change in growth.

[61] Growth in HeightAlright when we’re looking at height, we see the growth charts show us a distance cure okay. We have height and weight plotted, we have girls and boys who grow differently and at different times and adolescence in girls starts between ten and eleven years old whereas in boys between 12.5-13 years old. Yeah it lasts about 2.5 years for each of them but the starting point is different. Girls hit puberty a little bit earlier so of course if they hit it earlier they finish it earlier hence the reason why people are always saying girls are a little bit more mature than boys well they do they mature sooner but boys have the tendency to grow a little bit longer so they have tendency to be a little longer. So boys hit puberty later and they finish growing later. Okay, in girls menarche always follows the peak velocity of the adolescent spurt in height so once you meet menarche you’re pretty much met the height maximum. For boys, we grow for a longer period of time and often a girl is quite often for her age at school and is within puberty then they complete their growth at a younger age. All in all, the slower growers end up being the taller growers. This is kind of an overall average, there are exceptions to this rule. But for the most part this is an overall average.

[62] Distance CurveAlright here’s our distance curve our growth chart for a girl. If growth is interfered with it does not follow his specific. This particular girl that is plotted the red that you see there on the screen she’s following the 75th percentile of growth and it follows the growth charts. Here she stays within that percentile between 7 and 13 years old so she’s growing pretty well. And this is how we use the growth chart. The top one is the growth record, the bottom is the weight record over a period of time.

[63] Growth in weightThere is definitely more variatio in the weight than there is in the height and the reason is of course weight fluctuates on a more easily determined method and if we eat more you gain more weight so its not a distinct component of growth it can be fluctuant, that’s a good word. The average of the adolescent weight spurt in girls is 12 years old and in boys 14 years old. The peak velocity of the weight spurt lags behind the peak velocity of the height spurt on an average of about three months. So which happens first height or weight? Height or weight first? Height first. If you’re looking around, in our country we have an obesity issue and endemic if you will especially if you will. Our kids are very overweight and often times you see, the one area where we see our children developing very quickly you see the teenagers quite slender that’s because they’re going through a spurt of height and then they have a tendency to fill out afterwards. [64] Weight CurveIn this plotting is a young boy who as you can see around ten or eleven has started reflecting to the right and this is an indication that he’s not following the proper growth dimensions and if not then we basically looking at inappropriate growth. Disease, trauma something might have happened, cancer maybe. A severe change in his growth chart

[65] TimingOkay, timing is a major factor causing all these variations in our growth okay. Um, same events happen at different times for diff individuals when they occur. Most evident is at puberty. Growth spurts occurs t different times for different individuals. The heavier kids have a tendency to develop a little bit earlier on due to the hormones that are collected in the fat cells. Those that develop early on stop developing earlier on. Slow growing children have a tendency to catch up which we talked about a little more. I’m sure you’ve seen and as you go on with your training and your practicing is young girls nine ten years old and they’ve ben completely develop their breasts are developed and this is a scary time for us because that didn’t used to exist hundreds of years back. Maybe it’s the world the food we’re eating maybe the stress we’re under but timing is very variable. All sorts of things but timing is very variable.

[66] Timing plotAnd this is a plot a velocity plot of three different girls. M1, M2, and M3 and what you’re looking at here is girl 3 is taller than girl 1 and she grows for al longer period of time and can tell this by starting menarche at a later period of time. Okay its important to know when that occurs because for us orthodontics its necessary to know if significant growth exists for using orthodontic functional appliances and in conclusion age itself is not the

only good indicator for maturation status of growth and development. Skeletal growth is also very important. So what is the best way to assess if a person is grown. If a mother comes in and says my daughter is the shortest in her class, will she continue to grow? what is a good way to determine if she is going to continue to grow. I heard somebody. No? That’s yes the one way to look the epiphyseal plates we talked about yesterday.

[67] Indices of MaturityThere’s a series of indices of maturity which we will talk about now. Some of the indices that exist are gone through the velocity curve since chronological age is not necessarily an indicator of growth determination some of the developmental markers that we use one is height, one is weight, in girls it’s menarche, dental development, secondary sexual characteristics those are the ones that you notice things such as breasts, under arm hair, menarche girls, in boys it’s the Adams apple the change in voice hair on the face. Skeletal age we asses hand risk assay. We assess the appearance of the bones from the appearance of the calcification centers at the epiphyseal plate closure areas. And long bones and hand wrists also we look at the sesmoid bone to see fi its been calcified that’s an indication of growth stoppage. And of course we look at the overall demeanor and how he behaves. Is he a title more mature, are the gestures a little more mature.

[68] Timing velocity curveAlright looking at timing, this is a curve for four different girls who’s menarche took place different ages however if we superimpose the curve at 0.0 which is menarche is show the pattern in each girls velocity curve is similar with almost all of the variations resulting strictly from timing. When they start. So like we said before the fat cells are at retainer for accelerate hormonal growth young girls that her overweight have a tendency to develop faster get menarche faster and discontinue growth at a faster rate so they are a little bit shorter than some of the other young girls.

[ 69 ] Indices of maturity Morphologic changes such as height and weight sexual secondary characteristics and skeletal age are determinants of indices of maturity.

[70] Growth chartOkay and here is another growth plot of a girl on a female growth chart and she’s also growing in the 75th percentile in height and weight so that you guys can get a good idea of what the char tis like.

[71] Evaluation of hand-wrist radiographLooking at the growth rates of the long bones, we have several stages of development we have the one stage which is the ongoing growth phase, we have the capped stage which is the growth almost completed stage and then of course we have the fusion stage which is no longer completed and there is no longer an emptiness between epiphyseal plate and diaphsys9. You can also note that the sesmoid bone which is growing between the thumb and the first finger that calcifies completely by the time that growth is completed.

[72] Wrist radiographs

And then I just put these up this is a different stage of hand wrist films between a ten year old and fourteen year old female. Can you note the differences in the metacarpals here? See? There, and here. This is the capping stage or close to it and this is the need of growth and here’s your sesmoid bone right there.

[72] Evaluation of Cervical Vertebrae Maturation.Another way to look at growth and development is to evaluate is the cervical vertebrae maturation stags. There are basically six stages we’re looking at c2, c3 and c4. The cervical vertebrae stages one through 4 or 5 are outlined here for you and you can see through this animation what we’re looking at and your based on different combos of features and the bodies are c2 c3 and c4. The mandible completes growth between c2 and c3. We use this technique when have only one x ray to go by and that’s the only one in our position and we have to make a decisions or evaluation quickly. Pubertal peak is reached only at stage 2 and at least stage 2 before pubertal peak is reached.

CVMS I-IVAnd I put this up here because it thought you guys might like to see what you’re looking at. The C3, the stage 3 is the transitional stag and that stage is the distinct concavities seen in the lower borders of c2 and c3. You have a developing concavity seen in the lower border of C4. And that’s the stag where you have about 25-65 % of pubertal growth still remains. In the deceleration stage or stage four you only have about 10 percent remaining so you want to try to treat these kids before you reach the deceleration stage if you’re doing functional appliances.

[74] Indices of maturity.And finally the indices of maturity when you’re looking at dental age we’re looking at eruption, tooth development, length of the root development crown especially if you’re looking in a panoramic a mixed dentition you want to se how much of the root of the primary teeth are being resorbed. How much of the root of the primary teeth want to be elongated or formed before they erupt into the mouth. Lots of variation exists on this due to crowding genetics, trauma but it can give you a somewhat indication of growth and development. Alright guys that was a lot of info in part 1, that’s the end of part 1. So you can go stretch and if anybody has any questions you can come up and ask them.

Anybody have any specific question is Know that was a lot of material next time I might be a little more entertaining. So right now we’re talking about theories of craniofacial growth and development that are very exciting. The first two theories have been debunked but we have to know them because of them we have reached the third theory and this is one we have kind of continued work and functioned from right now and we have added to that theory and additional information package and we’re going tot get to that in just a bit. So there are two schools of thought in orthodontics at the moment and there seems to especially after the functional matrix theory evolved. There is always in fact a controversy that exists between opposing treatment modalities. To extract versus not extracting. To treat early versus treating late. Do you do functional appliances versus treating to take advantage of that growth and development. The thought process is let all the teeth erupt the two controversies are: let all the teeth erupt than address dental

malocclusion only once growth and development is completed. That’s one theory and one form of orthodontics, another theory is treat that child early get the most benefit out of growth and development, maximize that growth, and modify that growth in the direction you’d like to maximize intercuspal functioning and proper occlusion. And that’s the second theory. In order to answer which of these two beliefs you belong to we must discuss the following three theories and here they are.

[75] Theories of craniofacial growthFirst we have the sutural theory he primary cartilage theory and the functional matrix theory. Okay, before we go through that I just wanted to go through a little bit what is that we help to derive or achieve a theory that we can then emanate and then everybody follows. First we look at tour patients over a period of time we make observations after we gather all these we make a hypothesis that then becomes a theory and then in order for that to become a proper functioning theory we must test that theory. Once we test the theory we advance and go to the next step and implement that theory into our treatment modalities that’s how science and we move forward. When you’re thinking maybe its this maybe its this lemme try this, and if we try this and it works maybe we can do it again and again and again. Um, okay to what degree is the post natal growth purely genetic and which factors influence our osteogenous control system. That we will now at the end of our section of this discussion.

]76] Sights versus Centers of GrowthWe have sights versus centers of growth, these are generic academic concepts for academic us based on descriptive research characteristic of a population of a phenomenon being studied is a descriptive research. A site is a location where growth occurs and it is a reactive location to growth that reacts to other determinants or other areas that stimulate it is has no intrinsic tissue separating force at all. Examples of a site are condyles and sutures. A center is a genetically controlled area where growth is initiated and it has tissue separating force. Examples are craniofacial synchondrosis and our nasal cartilage.

[77] Sutural Growth TheoryWhat is our sutural growth theory. The sutural growth theory was introduced by Dr. Sicher in 1952. He hypothesized that the osteogenesis of the chondrocranium and the desmocranium is controlled genetically and the sutures are the dominant tissue structure’s. He observed new bone formation at synchondrosis at the mandibular base, the sutures and the occipital condyle, his theory was that pressure form these areas as they develop into bone push the bone apart displace the bone and hence the bone grows That’s his theory. He states that the osteogenesis is controlled genetically and thus the sutures are determinant themselves of tissue structure. They’re programmed genetically to grow that’s what he thought that was his theory of sutural growth. This theory states that this sites are both sites and centers of growth. Let me backtrack, this states that the sutures are both sites and centers of growth.TO test his theory he transplanted these sutures to different parts of the body usually in the abdomen the pectoralis area d what did we find

[78] Evidence against Sutures as Growth Centers

Evidence against this theory why? Because as he transplanted these sutures they failed to grow in the transplanted area they did not grow like they did in their original location then there’s areas are not primary growth centers. That’s not where genetics takes place. there is secondary cartilages and growth centers and these react to outside influences not reacting independently. And because this theory is not the ideal theory we took this went to the next level and said okay well not we have the sutures and we have the cartilage but what if its not the sutures themselves that are the growth areas what if it’s the cartilage so lets see maybe it’s the primary cartilage theory sit hew ay to go.

[79] Primary Cartilage TheorySo then professor Scott observed that the sutural theory is imperfect. He then theorized that the cartilage and the periosteum are the growth centers and that the sutures are the reactive or the passive centers. This theory states that cartilage does the growing the genetic area of growing stimulates from the cartilage but the bone replaces it. In this theory the mandibular condyle was considered a primary growth center because of its cartilage formation so you basically take this long bone and envision it dividing into two and bending if you will and now you have the mandibular bone and cartilage is on the ends and he’s stating that’s a primary growth center.

[80] Primary Cartilage TheoryIt was hypothesized that the condyle was like a diaphysis bone only between whereas the growth plate exists and grows forward. The modern theory shows us that while this theory is attractive it is in fact incorrect. We will go over that in just a minute and I’ll tell you why.

[82] Primary Cartilage TheoryHow can the cartilage determine maxilla growth if there is no endochondral bone formation there Why do you think Dr. Scott continued with this theory if he felt there was no endochondral formation in the maxilla and his answer was: because growth occurred secondary to resorption of the nasal cartilage a very large cartilage at the onset of the postnatal growth, stimulated this growth of the nasomaxiallary complex according to him. Although no cartilage exists in the maxilla there is cartilage in the nasal septum thus it was hypothesized that a growth in the nasal septum can lead to a downward and forward translation of the maxilla. An example of the theory is maxillary sutures are pulled apart by forces of the growing cartilage they respond by forming new bone. And here is the picture of the young nasal cartilage. At a very young age, the gray shading that you see there, all of this cartilage is then replaced by interseptal bone it’s a dramatic representation.

[83] Cartilage as a Growth CenterOf course we had to test this and the experimental approach to testing this and seeing if this is in fact a good theory um we did one of two things we did two things. First we transplanted the cartilage into diff locations in the body and we found that transplanting it we found that there exists two types of cartilage. Firs the primary cartilage which is the epiphyseal cart at the epiphyseal growth plate which grows when transplanted . Then you have the nasal septum which also grows when transplanted. Secondary cartilage is the

mandibular condyles which is surprising which is surprising. This does not grow when placed in different areas hence the reason why this cartilage does not apply to this growth theory. According to this primary cartilage theory, a condyle is the primary determinant for the growth of the mandible true or false base don what I just told you guys? False. This theory failed in its testing also with transplantation. The epiphyseal plate grows, nasal septum grows the condyle does not grow. According to the sutural theory, the sutures are the primary determinates of the craniofacial growth patterns, the sutural theory. True or false? True. According to that theory, we debunked it but it is true to that theory. The second way we debunked the cartilage theory is surgical removal of the cartilage. What happen sit does and will affect the site of growth. Malformations do occur.

[84] Is the condyle a growth center?Okay. And here’s what happens to that funny little condyle okay now that we notice that its secondary and does not grow when transplanted what happened with the condyle. We notice that there are frequently condylar fractures in young children therefore if the primary theory is correct than may children grow with growth impairments. What happens when her fracture occurs. The condyle absorbs and remodels to adapt to its new traumatized state. This is very important and is very important in treatment of orthodontic patients and orthognathic surgeries. You sometimes reposition it manipulate the condyle where its not the most ideal in location and does it can it regrow reposition remodel it does it restructures itself. Based on this knowledge we now know that the primary cartilage theory does not work. It is not the only theory. So is the condyle a growth center.

[85] Is the condyle a growth center? How often is this resorption that we talked about take place? Well in 75% of the time it was tested in Scandinavian in 1960 that in 75% of the time this resorption does take place. So most of the time if a young kid fell and fractured his condyle completely or incompletely often times if it was set for a little period of time eh would then grow normally for the rest of his growth stage. In lab animals they regenerate with a new layer of cartilage. This realization indicates that the condyle is reactive not a growth center. It is a growth site, not a growth center. Maybe a primary growth occurs in the condylar disc or capsule or fluid who knows this could be something that we want to study in the future but not at the condyle itself. The condyle like the suture are growth sites and not growth centers. Important to note. We may consider that all functional appliances done early enough may in fact lead to mandibular displacement which leads to growth at condyle which means to correcting malocclusion and profile improvement. A palatal suture and the palatal itself responds to a rapid maxillary expander secondary growth site actually what we know it that as thee expander expands it does not crack right at the sure tits does right next to it and as you’re moving apart he bone fills in and it’s a secondary suture if you will but it does function in the same way. Okay.

[86] Nasal Septum as Growth CenterHere is a little bunny and what we’re talking about here is the nasal septum. Is that a growth center? Orthodontics in Michigan removed the septum off the snout of a rabbit

and now our rabbit has a mid snout deficiency he grew like that so yes the septum is in fact a growth center. Here’s a gentleman at the age of 8 had a trauma and his septum had to be removed and he has a significant mid face deficiency horizontally and vertically. Okay.

[88] Functional Matrix TheoryNow we’re going to talk about the functional matrix theory. Dr. Moss who was at Columbia university in 1960 states that the growth of the face occurs as a response to functional needs and is mediated by the soft tissue in which the jaws are embedded Testing of the primary cartilage theory led to failure of this theory in the 1960’s Dr. Moss led the theory of the functional matrix which means the growth determinants were epigenetic meaning that fi they are not within the bone or the cartilage its within the surrounding tissue basically the skeletal structures grow on genetics that are found within the surrounding tissue. The skeleton is in response to the matrix of the cavities , muscles, organs, vessels, that all grow around it. There are two major components of the functional matrix. One component is the functional matrix itself and that’s the soft tissue cavities and that that is needed for a specific function like the oral cavity the nasal cavity and of course the skeletal unit. Micro skeletal which are little pieces sections of the bone where attachments of certain muscles exist to compiled together to create a macro skeleton like for example in the mandible and that is adaptable to the functional matrix. These are the two components to the functional matrix theory. What is the functional cranial component? The microskeletal units united to form the macroskeletal units all in which are surrounded by their own individual functional matrix, put together they compose a capsular matrix which when added together are the functional cranial components.

[89] Functional Matrix TheoryThe classical theory is that growth of the cranial vault is a direct response of growth of the brain that’s a classic example of the functional matrix theory as the brain grows the cranial vault grow s around it. If the brain doesn’t grow the vault remains small. In nature we see these experiments that have occurred naturally, anencephaly, microcephaly, and hydrocephaly. What is anencephaly? Anybody know? Not having a brain yeah they’re born that way. Microcephaly that’s small yes, and what’s hydrocephaly, yeah fluid in the ventricles and in the brain cavity and that fluid what it does is its hyper pressure of the brain cavity and that pressure evades its structure onto the cranial vault and what’s the reaction of the cranial vault? It enlarges. So people have a very large skull. These people could also have abnormalities in developmental issues but it appears as if they have an abnormally large brain. Okay.

[90] Functional Matrix TheoryThis is what we were talking about. The first child is an anecnhaplic, the second is a micro cephalic and the third is hydrocephalic child. Only 25% of children suffer a condylar fracture present mandibular growth deficiencies? Only 25%. Could the interference with function be the cause of the impairment could the interference of mandibular proper function be the reason that the impairments exists? Functional impairment due to anklyosis of the condyle or to scar tissue in the vicinity of the TMJ cause growth deficiencies in children after condyle fracture. So its not to say that the

condyle doesn’t resorb or reshape itself it’s the effect in the function of the lower jaw. If you can stabilize the lower jaw so this has time to reshape and reform and then let the lower jaw grow probably chances are it will grow well.

[91]Functional Matrix TheoryHere’s a young girl she’s a syndromal looking girl but she’s not a syndrome. She fell or had some sort of a trauma which lead to anklyosis of the mandible and the result or restriction of the mandibular growth is very apparent here. According to theories 1 and 2, or the sutural theory and the primary cartilage theory, this young girl is doomed to stay as she is just like this with an asymmetry that is very severe however because of the functional matrix theory you could establish proper function for her maintain this proper function, and then you will have some bone growth in the proper direction to where you can manipulate or orient bone growth long term.

[93] Functional Matrix TheoryOne of the ways we do this is called distraction osteogenesis, the rods you see placed in her face. Distraction osteogenesis is like the palatal expander, slow turning of these devices that will grow the bone in areas that you need areas them to. It doesn’t help in growing of the bite but it does help in growth and maturation of course and then the orthodontics part of it will help to adapt the bite to the newfound location of the bones. The functional matrix theory changed the way we currently practice orthodontics. It changed the way we practice because the whole way general practitioners look at young growing children and realize that growth is important and you don’t have to wait until growth is completed in order to start any kind of orthodontic orthopedic changes, because as a so maybe as a general practitioner, periodontist, maybe not so much a periodontist but the younger ones who see the younger group, you will begin to refer them to a orthodontist at an earlier age. (Student question) Definitely, if you jam that condyle up into the TMJ there is no doubt about that. There is so many ways that you can have trauma that can affect the head some more and some less than others, yep definitely. It’s necessary, Okay so I’m going back. As a pediatric dentist it would behoove you to know when to send that patient out for growth consults and you can in theory take advantage of growth to treat a class 2 or a class 3.

[94] CompromiseOkay current concepts and theories of growth we’re going to go through that really quickly right now this is the most current concept and this is my last slide. The current concept and theory of growth is we have a compromise or a combination of growth which is growth is affected by intrinsic genetic programming local actors epigenetic and environmental general factors, epigenetic, and environmental, Dr. Van Limbtberg came up with this theory and this is what we go by now nobody is the same everybody ahs as sight variation of growth and development but hat we do know is that growth does respond to a multitude of factors. Very quickly I just want to go through the functional matrix theory kind of the a b c of it. I’m just going to recapitulate the components of the functional matrix theory is you have the functional matrix itself and then you have the skeletal unit. Okay. The functional matrix is periosteal matrix and capsular matrix. The periosteal matrix is the muscles, the attachments, the capsular matrix is the nuerocranial

the orbital the orofacial sinuses. Okay. When you’re looking the neuro you’re looking at the brain the lepto meninges the CSF, oro sinuses you’re looking at naso-functional space, pharyngeal functional space. The skeletal unit is composed of two basic units, you have the micro skeletal which then evolves into the macro skeletal. One example of this is the mandible there’s a great picture of that in the books that I talked to you guys about yesterday. The functional cranial components we talked about that that’s the micro skeletal units combined to form the macro skeletal units all of which are surrounded by their own individual functional matrix but together they compose a capsular matrix which then added together are the functional cranial components. The capsular matrix is a direct influence on the macro skeletal units and functional cranial components. And is responsible for the three dimensional changes in the functional unit. These 3D changes often called translation, termed by moss in 1973, translation. The periosteal matrix changes the shape and the size of the corresponding micro skeletal unit. This is called transformation. One is translation, one is transformation. Translation almost always in the bone leads to transformation. Dr. Enlo in 1982 stated that the skull bones are transformed due to the effect of the related functional periosteal matrices.

[95] Thank YouOkay so quickly I want to backtrack, um. Epigenetics I find to be very exciting its exploding now a days. It’s a social behavioral studies it’s the influence fo epigenetics and environment on our behavior not a mutation in a gene. Its not the genes mutated for birth its basically what happens after it’s the environment affecting the expression of our gene. I wonder how much of that affects our growth and development as well. So now based on this functional matrix theory and the new theories of growth what we can state is that in orthodontics it becomes very important to take this into consideration we use appliances such as the frankel tube, the herpst, or the Mara pliance or the twin block or bike plate etc multitude of appliances which can then help to modify growth and development. Reversal head gear, rapid maxillary expander all of which is done at a very young age, 6 and 7. Actually I treated my son who was three and half he was born with a complete under bite. Half was in an under bite and I put a removal appliance in of course every night being his mom he had that removal appliance removed. But he enjoyed it was fun and it was exciting with all the colors for him and within a year that complete cross bite was gone I never had to do a rapid palatal expander on him. He was a class III skeletally but never had to do surgery on him. So done at a very young age it can significantly influence growth and dev. There’s something really excited that I’m now interested in and that’s bone plates which are like an implant but they’re plated and you place them in certain areas of the maxilla and mandible sub gingivally you put the flap back on and in the areas that are sticking out from the gingiva you can now run class three rubber bands using them in young enough cases once you’ve done expansion of the maxilla say in ten or eleven year olds while there’s still sig growth occurring you can bring that maxilla forward a good three four maybe five millimeters which is a good movement for the maxilla which doesn’t move. This is very new very cutting edge not a routine practice in orthodontic cases but maybe it will be you know it’s tough to say. It’s tough to tell parents I’m going to but bone plates in your child’s mouth for the next year but it’s a surgical procedure but look we thought that about TADs or temporary Anchorage devices. We thought nobody would want a surgical procedure done to move teeth but

now we do it in our office. A little anesthetic goes through the gingiva we do it in our office you don’t even have to draw a flap and lots more people are accepting is as a normal treatment modality when going through orthodontics. Things evolve. Do you guys have any questions? We’re done, and early. You guys have any questions?