**DMD Level 2** # Unit A: Diagnostic Procedures ## Orthodontic Seminar * **Part 1. Malocclusion: what is it and why should we treat it?** * **Part 2. The etiology of malocclusion** THE UNIVERSITY OF WESTERN AUSTRALIA #### DMD Level 2 Orthodontic Seminar This unit covers the fundamental aspects of malocclusion, divided into the following primary areas of study: - **Part 1. Malocclusion: what is it and why should we treat it?** - **Part 2. The etiology of malocclusion** **Part 1. Malocclusion: what is it and why should we treat it?** **Be sure that you are able to:** 1. Describe ideal occlusion in terms of the relationship of the teeth to the line of occlusion. 2. Describe ideal occlusion in terms of the occlusal relationship of the teeth in all three planes of space (transverse, antero-posterior and vertical). 3. List the dental characteristics on which the Angle classification is based. 4. Discuss the advantages of the Angle system for classification. 5. Describe the functional, health and psychosocial reasons for orthodontic treatment, and place them in perspective in terms of their relative importance. 6. Describe realistic goals for orthodontic treatment, and indicate the way they have changed as modern dentistry developed. 7. Discuss how need for orthodontic treatment compares with demand in the US at present and how demand is likely to change in the near future. #### Learning Objectives 1. Describe ideal occlusion in terms of the relationship of the teeth to the line of occlusion. 2. Describe ideal occlusion in terms of the occlusal relationship of the teeth in all three planes of space (transverse, antero-posterior and vertical). 3. List the dental characteristics on which the Angle classification is based. 4. Discuss the advantages of the Angle system for classification. 5. Describe the functional, health and psychosocial reasons for orthodontic treatment, and place them in perspective in terms of their relative importance. 6. Describe realistic goals for orthodontic treatment, and indicate the way they have changed as modern dentistry developed. 7. Discuss how need for orthodontic treatment compares with demand in the US at present and how demand is likely to change in the near future. _figures/img_823c64141032b770.webp) _figures/img_c13644edaf26b2c3.webp) Clinical photograph showing the upper dental arch from an occlusal view. A yellow line traces the 'Upper line of occlusion,' connecting the incisal edges of the anterior teeth to the occlusal surfaces of the posterior teeth, illustrating the alignment of the maxillary dentition. Clinical photograph showing the lower dental arch from an occlusal view. A yellow line traces the 'Lower line of occlusion,' following the curvature of the mandibular teeth, demonstrating the relationship of the lower dentition to the occlusal plane. Angle described deviations from the line of occlusion _figures/img_4550e1f46c570fd3.webp) Angle described deviations from the line of occlusion. Labelled diagram illustrating Angle described deviations from the line of occlusion. The visual depicts a dental arch outline with individual teeth drawn in cyan against a dark reddish-brown background. Five specific types of tooth inclination are labeled: 'BUCCOVERSION' at the upper right, 'LINGUOVERSION' in the center, 'TORSIVERSION' at the bottom left, and 'LABIOVERSION' at the bottom right. _figures/img_75d02cccd69140a5.webp) Clinical photograph of the maxillary dental arch viewed from above (occlusal view). The image displays the upper teeth and palate. A yellow curved line traces the dental arch form, connecting the central incisors to the posterior molars on both sides. White arrows point to specific anatomical features along the arch: one at the midline between the central incisors, one near the premolar region, and one near the molar region. The caption 'Normal?' suggests this is a diagnostic or educational example used to illustrate or question the typical shape of the dental arch. OR IS IT RANGE WHERE VALUES DICTATE THE CUT-OFF? _figures/img_b56614c4e3c9104f.webp) _figures/img_46a6de199967444e.webp) OR IS IT RANGE WHERE VALUES DICTATE THE CUT-OFF? Labeled diagram showing a horizontal gradient bar with 'GOOD' (left) and 'BAD' (right). A yellow vertical line marks a cut-off point. Green arrows indicate directionality. The region to the right of the cut-off is labeled 'MALOCCLUSION'. Second labeled diagram similar to the first, but with the yellow vertical cut-off line shifted further to the left. The 'MALOCCLUSION' range extends further into the 'GOOD' spectrum compared to the top diagram. _figures/img_f610e54a6e4b57bb.webp) Clinical intraoral photograph of the mandibular dental arch. The image shows a patient's lower teeth with visible carious lesions (decay) on multiple molars. A yellow curved line outlines the dental arch, and two black arrows point to specific anterior teeth near the midline, likely indicating areas of clinical interest or pathology. _figures/img_933b38dbb9b528aa.webp) Clinical photo of an upper dental arch showing the occlusal view of teeth and gingiva. A yellow line traces the dental arch shape, with black arrows pointing to specific teeth or anatomical landmarks. Describe ideal occlusion in terms of the occlusal relationship of the teeth in all three planes of space (transverse, antero-posterior and vertical). Describe ideal occlusion in terms of the occlusal relationship of the teeth in all three planes of space (transverse, antero-posterior and vertical). **DR. EDWARD H. ANGLE** Ideal occlusion described in detail as found in an American Indian skull _figures/img_b049965a0ef5fa30.webp) _figures/img_7baa300df5535acd.webp) #### Historical Context Dr. Edward H. Angle described ideal occlusion in detail as found in an American Indian skull. Black and white portrait photograph of Dr. Edward H. Angle, identified by the caption at the bottom. He is wearing glasses and a suit. Lateral view photograph of a human skull demonstrating ideal occlusion as described by Dr. Angle, specifically noted in the OCR context as being found in an American Indian skull. The image shows the alignment of teeth with the mandible positioned correctly against the maxilla. # Class 1 Normal _figures/img_8a2d21990982a832.webp) _figures/img_498773ef19fe991a.webp) #### Class 1 Normal Clinical photo showing the maxillary occlusal view of a Class 1 Normal dentition. The image displays the upper arch with well-aligned teeth and healthy pink gingiva. Clinical photo showing the mandibular occlusal view of a Class 1 Normal dentition. A metal lingual arch appliance is visible on the lower anterior teeth, used for space maintenance or stabilization. • List the dental characteristics on which the Angle classification is based. - List the dental characteristics on which the Angle classification is based. DR. EDWARD H. ANGLE Ideal occlusion described in detail as found in an American Indian skull <portrait> Dr. EDWARD H. ANGLE </portrait> <skull-diagram> Skull showing zygomatic arch and teeth alignment </skull-diagram> _figures/img_1c30e951bf98bfd3.webp) _figures/img_83353ad5d75ee4e5.webp) #### Historical Documentation Dr. Edward H. Angle described ideal occlusion in detail as found in an American Indian skull. Documentation includes portraits of Dr. Angle and skull diagrams showing the zygomatic arch and teeth alignment. Portrait photograph of Dr. Edward H. Angle with glasses and formal attire. Lateral view of a skull showing teeth alignment and zygomatic arch, circled for emphasis. Angle classified the occlusal relationships of the teeth. His classification had four parts. * Normal occlusion * Class I malocclusion * Class II malocclusion * Class III malocclusion _figures/img_f64ea6880c5002ba.webp) Angle classified the occlusal relationships of the teeth into four parts: - Normal occlusion - Class I malocclusion - Class II malocclusion - Class III malocclusion Diagram illustrating Angle's classification of occlusal relationships. It consists of four distinct ovals representing the categories: 'Normal occlusion' (light blue), 'Class I malocclusion' (orange), 'Class II malocclusion' (green), and 'Class III malocclusion' (grey). • Discuss the advantages of the **Angle system** for classification. - Discuss the advantages of the Angle system for classification. • Describe the functional, health and psychosocial reasons for orthodontic treatment, and place them in perspective in terms of their relative importance. - Describe the functional, health and psychosocial reasons for orthodontic treatment, and place them in perspective in terms of their relative importance. # Why do orthodontics? **1.** Reduce psychosocial handicap **2.** Improve oral function **3.** Adjunct to disease control - not to treat disease #### Primary Objectives of Orthodontics 1. Reduce psychosocial handicap 2. Improve oral function 3. Adjunct to disease control (not to treat disease) • Describe realistic goals for orthodontic treatment, and indicate the way they have changed as modern dentistry developed. - Describe realistic goals for orthodontic treatment, and indicate the way they have changed as modern dentistry developed. • Describe realistic goals for orthodontic treatment, and indicate the way they have changed as modern dentistry developed. **Angle vs Soft Tissue Paradigm: A New Way of Looking at Treatment Goals** | Feature | Angle Paradigm | Soft Tissue Paradigm | |-----------------------------|------------------------------------------|------------------------------------------------------| | **Primary goal of treatment** | ideal dental occlusion | ideal soft tissue proportions and adaptation | | **Secondary goal of treatment** | jaw relationships | functional occlusion | | **Hard vs soft tissue relationship** | ideal skeletal/dental produces ideal soft tissue | ideal soft tissue defines ideal skeletal/dental | | **Diagnostic emphasis** | dental casts, cephalometric x-rays | clinical examination of soft tissues | | **Treatment approach** | obtain ideal dental and skeletal relationships, and the soft tissues will be OK | determine ideal soft tissue relationships, and then place the jaws and teeth as needed to obtain them | _figures/img_dbd4fecb152c094e.webp) _figures/img_f566a5300631f4d3.webp) _figures/img_0f5945de18d0c227.webp) _figures/img_00ba1c1a34f42eea.webp) #### Angle vs Soft Tissue Paradigm: A New Way of Looking at Treatment Goals | Feature | Angle Paradigm | Soft Tissue Paradigm | | :--- | :--- | :--- | | **Primary goal of treatment** | Ideal dental occlusion | Ideal soft tissue proportions and adaptation | | **Secondary goal of treatment** | Jaw relationships | Functional occlusion | | **Hard vs soft tissue relationship** | Ideal skeletal/dental produces ideal soft tissue | Ideal soft tissue defines ideal skeletal/dental | | **Diagnostic emphasis** | Dental casts, cephalometric x-rays | Clinical examination of soft tissues | | **Treatment approach** | Obtain ideal dental and skeletal relationships, and the soft tissues will be OK | Determine ideal soft tissue relationships, and then place the jaws and teeth as needed to obtain them | Comparison chart comparing the 'Angle paradigm' and 'Soft tissue paradigm'. Under 'Primary goal of treatment', Angle paradigm lists 'ideal dental occlusion' while Soft tissue paradigm lists 'ideal soft tissue proportions and adaptation'. The image is a single panel from a set of four. Comparison chart continuing the comparison between paradigms. It lists 'Secondary goal of treatment': Angle paradigm has 'jaw relationships' and Soft tissue paradigm has 'functional occlusion'. This is the second panel in the top row. Comparison chart showing 'Hard vs soft tissue relationship'. Angle paradigm states 'ideal skeletal/dental produces ideal soft tissue', whereas Soft tissue paradigm states 'ideal soft tissue defines ideal skeletal/dental'. This is the third panel in the bottom row. Comparison chart detailing 'Diagnostic emphasis' and 'Treatment approach'. Diagnostic emphasis for Angle paradigm is 'dental casts, cephalometric x-rays' vs 'clinical examination of soft tissues' for Soft tissue paradigm. Treatment approach for Angle paradigm is 'obtain ideal dental and skeletal relationships, and the soft tissues will be OK', while Soft tissue paradigm is 'determine ideal soft tissue relationships, and then place the jaws and teeth as needed to obtain them'. This is the fourth panel in the bottom row. Discuss how need for orthodontic treatment compares with demand in the US at present and how demand is likely to change in the near future. Discuss how need for orthodontic treatment compares with demand in the US at present and how demand is likely to change in the near future. **TREATMENT** TREAT malocclusion- no treatment malocclusion- treatment normal _figures/img_d010d55208c91204.webp) #### Treatment Categories - Normal - Malocclusion - no treatment - Malocclusion - treatment Labeled pie chart titled 'TREATMENT' displaying three categories. The top-left slice is teal, labeled 'normal'. The bottom slice is dark blue, labeled 'malocclusion-treatment'. The top-right slice is light blue, labeled 'malocclusion-no treatment'. The text 'TREAT' appears in white on the dark blue slice. The chart compares the median family income of all other races with median family income for Hispanic origin races in 2010 and 2010-2012, as measured by the median family income, and shows that the median family income for all other races in 2010 was $59,914 and that the median family income for Hispanic origin races in 2010 was $36,771, and that the median family income for all other races in 2010-2012 was $55,626 and that the median family income for Hispanic origin races in 2010-2012 was $37,035. 2010 $59,914 $36,771 Median Family Income 2010-2012 $55,626 $37,035 Median Family Income Other Race Hispanic Origin _figures/img_483630630ae50e24.webp) #### Socioeconomic Factors: Median Family Income Comparison **2010 Data** - All other races: $59,914 - Hispanic origin: $36,771 **2010-2012 Data** - All other races: $55,626 - Hispanic origin: $37,035 Stacked bar chart comparing the percentage of population needing treatment by severity across three racial/ethnic groups: White, Black, and Hispanic. The y-axis represents 'Percent of population' ranging from 0 to 60+. The x-axis labels are 'White', 'Black', and 'Hispanic'. A legend on the right indicates severity levels based on IOTN (Index of Orthodontic Treatment Need): Blue for Severe (IOTN 4,5), Teal/Greenish-blue for Moderate (IOTN 3), and Light Green for Mild (IOTN 2). Visually, the Black group has the highest total need for treatment, followed by the White group, then the Hispanic group. The Hispanic group shows the smallest proportion in the 'Mild' category. # **Who seeks orthodontic treatment?** - 65% have malocclusion - Dentists feel that **55%** need treatment - Patients feel that **35%** need treatment <img>Pie chart showing malocclusion types (Class I, Class II, Class III, Normal Occlusion) _figures/img_edd01f626d893635.webp) #### Who seeks orthodontic treatment? - 65% of the population have malocclusion. - Dentists feel that 55% need treatment. - Patients feel that 35% need treatment. Distribution includes Class I, Class II, Class III, and Normal Occlusion. Pie chart showing malocclusion types (Class I, Class II, Class III, Normal Occlusion) Do lay people not recognize problems OR do they place different values on the benefits of treatment? Do lay people not recognize problems OR do they place different values on the benefits of treatment? In fact **lay people** can discriminate between good and bad teeth. It is simply that they place different value on the treatment to address the problem. Lay people can discriminate between good and bad teeth. It is simply that they place different value on the treatment to address the problem. # But who gets treatment? Range 5-40% many factors influence this decision socioeconomic? #### Treatment Utilization - Range: 5-40% get treatment. - Many factors influence this decision, including socioeconomic status. **Increasing adult demands** • Job advancement • Need to “trade up” #### Increasing Adult Demands - Job advancement - Need to "trade up" <table> <tr> <th colspan="2">Would benefit from treatment</th> </tr> <tr> <td>Dentists</td> <td>55%</td> </tr> <tr> <td>Lay people</td> <td>35%</td> </tr> <tr> <td>Would accept-no cost</td> <td>50%</td> </tr> </table> _figures/img_2cc4452fde546b21.webp) #### Perception of Treatment Benefit - Dentists: 55% - Lay people: 35% - Would accept if no cost: 50% A cartoon illustration of a bee wearing yellow sunglasses. The figure is positioned in the bottom right corner of the slide and serves as a decorative visual element. # Treatment * 55% Need treatment * 50% Accept treatment at no cost * 5% Wouldn't accept treatment » Even if it was free #### Treatment Acceptance Rates - 55% Need treatment - 50% Accept treatment at no cost - 5% Wouldn't accept treatment even if it was free # Summary * **Malocclusion** is defined as a deviation of the line of occlusion or it may be a deviation in the way the teeth relate * **Malocclusion** is more prevalent than normal occlusion * **Most malocclusion** is dental crowding-but **15%** have a skeletal problem #### Summary - **Malocclusion** is defined as a deviation of the line of occlusion or a deviation in the way the teeth relate. - **Malocclusion** is more prevalent than normal occlusion. - **Most malocclusion** consists of dental crowding, but 15% have a skeletal problem. Part 2. The etiology of malocclusion - Describe known causes of malocclusion in terms of major categories, and put the known causes in perspective relative to the total number of patients with malocclusion. - Indicate the two types of malocclusion most likely to be due to inherited jaw proportions, and describe the evidence to support your categorization. - Indicate the mechanism by which trauma to the mandible can affect its future growth. - Identify the magnitude of force needed to cause movement of a tooth, and relate this to the observed threshold for tooth movement. - Identify the duration of force needed to cause movement of a tooth, and relate this to the impact of habits like thumb sucking on the dentition. - Describe the maturation of oral function from infancy to adult life, with particular emphasis on the pattern of swallow. - Discuss myofunctional therapy for tongue thrusting as a potential therapy for anterior open bite in children, with emphasis on its underlying assumptions and their validity. - Describe the possible role of nasal obstruction in the etiology of malocclusion, and indicate the probable mechanism by which it would have an effect. #### Learning Objectives - Describe known causes of malocclusion in terms of major categories, and put the known causes in perspective relative to the total number of patients with malocclusion. - Indicate the two types of malocclusion most likely to be due to inherited jaw proportions, and describe the evidence to support your categorization. - Indicate the mechanism by which trauma to the mandible can affect its future growth. - Identify the magnitude of force needed to cause movement of a tooth, and relate this to the observed threshold for tooth movement. - Identify the duration of force needed to cause movement of a tooth, and relate this to the impact of habits like thumb sucking on the dentition. - Describe the maturation of oral function from infancy to adult life, with particular emphasis on the pattern of swallow. - Discuss myofunctional therapy for tongue thrusting as a potential therapy for anterior open bite in children, with emphasis on its underlying assumptions and their validity. - Describe the possible role of nasal obstruction in the etiology of malocclusion, and indicate the probable mechanism by which it would have an effect. • Describe known causes of malocclusion in terms of major categories, and put the known causes in perspective relative to the total number of patients with malocclusion. • Hereditary factors • Interference with normal development • Trauma • Disturbance with normal function #### Primary Etiological Categories - Hereditary factors - Interference with normal development - Trauma - Disturbance with normal function **CAUSES OF MALOCCLUSION** 1. Facial form and congenital anomalies 2. Postnatal Growth Disturbances 3. Inherited Facial Disproportions 4. Environmental Causes #### Classification of Causes 1. Facial form and congenital anomalies 2. Postnatal Growth Disturbances 3. Inherited Facial Disproportions 4. Environmental Causes # AETIOLOGY OF MALOCCLUSION • 5% KNOWN – THE REST-UNKNOWN _figures/img_1cebfade828f0134.webp) _figures/img_903b43bad9588bf3.webp) #### Prevalence of Known Causes - 5% Known - The rest (95%) Unknown Pie chart titled 'AETIOLOGY OF MALOCCLUSION'. The chart is divided into four segments: Malocclusion (60%, blue), Normal occlusion (35%, light blue), Denofacial deformity (5%, dark grey), and Known cause (5%, orange). A text label at the top states '5% KNOWN – THE REST-UNKNOWN'. Simplified pie chart showing proportions of three categories. Legend indicates: Normal (light purple), Known (maroon), Unknown (yellow). The visual shows a large unknown portion, a smaller normal portion, and a small known portion. - Indicate the two types of malocclusion most likely to be due to inherited jaw proportions, and describe the evidence to support your categorization. Indicate the two types of malocclusion most likely to be due to inherited jaw proportions, and describe the evidence to support your categorization. # Inherited Facial Disproportions _figures/img_17d8ea4a8af0ba48.webp) _figures/img_9102d2c6fbaa1c86.webp) _figures/img_802e931e50dbe303.webp) Inherited Facial Disproportions Portrait photograph of a man with a white wig and ruffled collar, illustrating inherited facial disproportion. Painted portrait of a man in armor and red cloak, illustrating inherited facial disproportion. Stamp featuring a historical map and a figure on horseback, illustrating inherited facial disproportion. # Twin studies, family studies and dog studies _figures/img_f65ce811c88ef389.webp) _figures/img_b3b3807ecefac43f.webp) #### Research Methodologies - Twin studies - Family studies - Dog studies Clinical photo: Lateral profile view of a young female patient demonstrating Class III malocclusion (underbite) and mandibular prognathism. Clinical photo: Intraoral close-up showing severe crowding in the upper dental arch with labially displaced maxillary incisors. • Indicate the mechanism by which trauma to the mandible can affect its future growth. Indicate the mechanism by which trauma to the mandible can affect its future growth. _figures/img_96f44a196ae8c988.webp) Figure showing six panels (A-F) of a comparative skull analysis. Panels A and B are lateral views; Panel C is an anterior view with a red line indicating the transverse plane for sectioning shown in D (posterior view). Panels E and F are superior views with orientation labels 'right' and 'left'. The figure demonstrates anatomical differences between two specimens. _figures/img_9accd045ee4a4f97.webp) A composite medical figure displaying six black-and-white photographs of an adult monkey skull (labeled A-F) demonstrating the effects of a condylectomy. The layout consists of three rows: the top row shows lateral views from different angles; the middle row displays anterior and posterior views; and the bottom row presents superior (base) views with 'right' and 'left' orientation markers. Text overlays indicate that the subject is an 'Adult Monkey' and describe the finding as 'Collapses on condylectomy side', highlighting the anatomical changes or displacement resulting from the surgical procedure. _figures/img_43eddef307e2f9d0.webp) Clinical radiograph (lateral view) showing the mandible and teeth. The image demonstrates a dental pathology where the roots of the posterior teeth appear fused to or embedded within the alveolar bone structure, suggestive of ankylosis or severe periodontal disease. A white dashed line traces the superior contour of the soft tissue/mucosa along the anterior aspect. Condyle fractures Lateral pterygoid displaces medially and anteriorly Mandible may shift to right _figures/img_aa561734401e5005.webp) #### Condyle Fractures - Lateral pterygoid displaces medially and anteriorly - Mandible may shift to the right Anatomical diagram of a mandible illustrating condyle fractures. The image includes an inset showing the lateral pterygoid muscle displacing the fractured condyle medially and anteriorly. Labels indicate 'Condyle fractures' with an arrow pointing to the fracture site, 'Lateral pterygoid displaces medially and anteriorly', and 'Mandible may shift to right' with a curved arrow indicating displacement. # EFFECT OF FRACTURE OF MANDIBULAR CONDYLE IN CHILDREN * **75% - Condyle regenerates** No growth deficit * **25% - Partial regeneration** Growth deficit occurs #### Effect of Fracture of Mandibular Condyle in Children - **75% - Condyle regenerates**: No growth deficit - **25% - Partial regeneration**: Growth deficit occurs In order to grow properly, the mandible must be able to # TRANSLATE Opening on a hinge is not enough! ```mermaid graph TD A[Ankylosis of mandible] --> B[Fusion across Temporomandibular joint] B --> C[Restricts motion] C --> D[Inhibits growth] ``` _figures/img_0f57c113a8599bec.webp) #### Mandibular Translation In order to grow properly, the mandible must be able to translate. Opening on a hinge is not enough. - Ankylosis of mandible leads to fusion across the Temporomandibular joint. - This fusion restricts motion. - Restricted motion inhibits growth. Flowchart diagram illustrating the progression of mandibular ankylosis. The flow starts with 'Ankylosis of mandible' (blue box) pointing to 'Fusion across Temporomandibular joint' (light blue box), which leads to 'Restricts motion' (yellow box), and finally 'Inhibits growth' (orange box). Pink arrows indicate the sequence. Accompanying text on the left states: 'In order to grow properly, the mandible must be able to TRANSLATE' and 'Opening on a hinge is not enough!'. **Fractures** **Condyle in early childhood** <img>Photo of a young child indicating jaw condyle fracture _figures/img_3ed94bd1e91f9fca.webp) #### Early Childhood Fractures Fractures of the condyle in early childhood. Clinical photo of a young child with blond hair and freckles. A red arrow points to the right mandibular condyle region, indicating the site of a fracture. A red line is drawn across the lower face, likely as a reference for facial asymmetry or deviation caused by the injury. _figures/img_a4b5703c5a509e12.webp) Clinical profile photograph of a child showing facial features. An annotation with an orange arrow and the text 'Chin retrusive' points to the chin area. **Ankylosis- from scarring** _figures/img_e9976b6e30851492.webp) #### Ankylosis Ankylosis resulting from scarring. Clinical figure showing three radiographic panels of a mandibular condyle. The image demonstrates the progression or stages of ankylosis resulting from scarring. Red arrows point to the joint space area in each panel, indicating the fusion of bone and loss of the normal joint cavity. **Remove ankylosed joint** _figures/img_d4da2d072c6df3ec.webp) #### Surgical Intervention Remove ankylosed joint. Clinical photograph showing a surgically removed specimen of an ankylosed joint. The tissue is reddish-pink with a rounded head-like structure on the left and a tapered shaft extending to the right, resembling a small bone fragment or fused joint segment. A ruler in centimeters (marked 1–4 cm) is placed below for scale. The background is blue surgical drape. Replace with something which grows at the same rate _figures/img_361c3ccc966159cd.webp) _figures/img_4b484d06171eaac2.webp) #### Joint Replacement Replace with something which grows at the same rate. Clinical photo of a human rib cage skeleton showing the thoracic vertebrae and ribs. Photo of a meal consisting of grilled meat (ribs or steak), breadsticks, and side dishes on plates. _figures/img_4eda7f506cadfa90.webp) Portrait photograph of a young boy with blonde hair and blue eyes. He is wearing braces on his teeth and has a dark collared shirt over a white undershirt. The background is solid blue. • Identifying the magnitude of force needed to cause movement of a tooth, and relating this to the observed threshold for tooth movement. Identifying the magnitude of force needed to cause movement of a tooth, and relating this to the observed threshold for tooth movement. _figures/img_f836511d7eb2ebe1.webp) Line chart showing 'Microns of Plate Separation' (y-axis, 500-700) versus 'Time (hours)' (x-axis, 0-5). The graph tracks three distinct curves labeled A, B, and C. Key annotations include 'Unimpeded eruption rate' pointing to the initial slope at t=1, 'Impeded eruption rate' indicating a plateau in curve C around t=3, and arrows marking 'force on' and 'force off' events that correspond to changes in the plate separation trends. • Identify the duration of force needed to cause movement of a tooth, and relate this to the impact of habits like thumb sucking on the dentition. Identify the duration of force needed to cause movement of a tooth, and relate this to the impact of habits like thumb sucking on the dentition. _figures/img_864e718b91ed5f58.webp) Line chart showing Eruption (Microns) on the y-axis versus Time (Hours) on the x-axis. The graph displays three distinct trend lines with data points labeled at the end: 147, 148, and 167. Annotations include 'On' and 'Off' markers along the curves, indicating force application cycles. A text box in the upper left specifies experimental conditions: '3 Gms. Force', '1 Sec: 9 Secs.'. 3 Gms. Force 1 Sec: 3 Secs. **Eruption (Microns)** * 300 * 200 * 100 * 0 **Time (Hours)** * 1.0 (Force On) * 2.0 (Force Off) * 3.0 (Force On) * 4.0 (Force Off) * 5.0 **Graph Labels:** 146, 139, 156, 150 _figures/img_4962c384de6eb33c.webp) #### Force and Eruption Data - Force: 3 Gms. - Intervals: 1 Sec to 3 Secs. **Eruption (Microns) over Time (Hours):** - 1.0 Hour: Force On - 2.0 Hours: Force Off - 3.0 Hours: Force On - 4.0 Hours: Force Off - 5.0 Hours Line chart showing 'Eruption (Microns)' on the Y-axis (0-300) versus 'Time (Hours)' on the X-axis (0-5.0). Four data series are plotted with values labeled at the end: 146, 139, 156, and 150. The graph includes annotations for experimental conditions: '3 Gms. Force' and '1 Sec: 3 Secs.' Key events marked include 'Force On' at t=1.0h, 'Force Off' at t=2.0h, 'Force On' at t=3.0h, and 'Force Off' at t=4.0h. Figure showing eruption (microns) over time (hours). Labels On, Off, and Error bars. _figures/img_3b46990e603a0201.webp) Figure showing eruption (microns) over time (hours) with On/Off force cycles and error bars. Line chart showing Eruption (Microns) on the y-axis versus Time (Hours) on the x-axis. The graph displays multiple trend lines tracking eruption measurements over a 5-hour period. Key annotations include 'On' and 'Off' markers indicating force application cycles at approximately 1.0, 2.0, 3.0, and 4.0 hours. A text box specifies conditions: '3 Gms. Force' and '1 Sec: 1 Sec.' Specific data points are labeled with values such as 169, 153, 154, and 155 near the end of the timeline. CONCLUSIONS - **INTERMITTENT LIGHT FORCE** AFFECTS THE ERUPTION OF THE RABBIT INCISOR - **50% TIME:** SIMILAR TO CONTINUOUS FORCE - **25% TIME:** INTERMEDIATE EFFECT (individual variation) - **10% TIME:** LITTLE OR NO EFFECT _figures/img_540b246ab117c667.webp) #### Conclusions on Intermittent Force Intermittent light force affects the eruption of the rabbit incisor based on duration: - **50% Time**: Similar to continuous force - **25% Time**: Intermediate effect (individual variation) - **10% Time**: Little or no effect A summary table listing the effects of intermittent light force on rabbit incisor eruption at different time intervals. The first column lists percentages (50%, 25%, 10%) and the second column describes the corresponding effect (Similar to continuous force, Intermediate effect with individual variation, Little or no effect). _figures/img_5e8974fdf9a4df29.webp) Clinical intraoral photograph showing the maxillary and mandibular anterior dentition. The image captures the upper central incisors with a noticeable midline diastema (gap). There is evidence of dental caries on the labial surface of the right maxillary central incisor, characterized by discoloration and structural loss. The lower anterior teeth appear relatively aligned, while the posterior regions show mixed dentition with visible primary molars and erupting permanent premolars. • Describe the maturation of oral function from infancy to adult life, with particular emphasis on the pattern of swallow. Describe the maturation of oral function from infancy to adult life, with particular emphasis on the pattern of swallow. A Relaxed Lip Closure B Forced Lip Closure _figures/img_409e72471b102482.webp) #### Lip Posture - A: Relaxed Lip Closure - B: Forced Lip Closure Anatomical diagram illustrating the difference between relaxed and forced lip closure. The image is divided into two panels: Panel A shows a sagittal cross-section of the oral cavity with 'Relaxed Lip Closure' indicated by arrows pointing to an open mouth; Panel B shows a similar view with 'Forced Lip Closure,' depicting a closed mouth. Both diagrams highlight the tongue, teeth, and soft palate structures. • Discuss myofunctional therapy for tongue thrusting as a potential therapy for anterior open bite in children, with emphasis on its underlying assumptions and their validity. Discuss myofunctional therapy for tongue thrusting as a potential therapy for anterior open bite in children, with emphasis on its underlying assumptions and their validity. Describe the possible role of nasal obstruction in the etiology of malocclusion, and indicate the probable mechanism by which it would have an effect. Describe the possible role of nasal obstruction in the etiology of malocclusion, and indicate the probable mechanism by which it would have an effect. **EVIDENCE** * LINDER-ARONSON EXPERIMENTS * VIG EXPERIMENTS #### Evidence Sources - Linder-Aronson experiments - Vig experiments _figures/img_8846286e334626ba.webp) Lateral cephalometric radiograph comparison diagram. The image displays two superimposed skeletal profiles of a child's head: the solid white line represents 'Control children' and the dashed white line represents 'Adenoidectomy children', as indicated by the legend at the top. The diagram highlights differences in facial growth patterns, particularly in the midface region (nasal profile and maxilla) and mandibular position, likely illustrating the effects of adenoid removal on craniofacial development. **CONCLUSION** • PARTIAL NASAL OBSTRUCTION IN HUMANS TENDS TO INCREASE FACE HEIGHT **HOW MUCH?** #### Conclusion Partial nasal obstruction in humans tends to increase face height. **CONCEPT** MODE OF RESIBRATION MAKES SOME DIFFERENCE AS IT ALTERS POSTURAL RELATIONSHIPS – CHANGE IN RESTING PRESSURES #### Mechanism Concept Mode of respiration makes a difference as it alters postural relationships, leading to a change in resting pressures. EVIDENCE **LINDER-ARONSON EXPERIMENTS** **VIG EXPERIMENTS** #### Evidence - Linder-Aronson experiments - Vig experiments _figures/img_be60b3a4d37e8cc9.webp) Line drawing diagram of a human head in profile facing left. The image features the outline of the skull and neck, with specific focus on the ear region. A rectangular box is superimposed over the lower face and jaw area, containing internal lines that appear to represent anatomical structures or measurement guides. There are small labels inside the rectangle, including what appears to be 'cm' text. The style suggests a medical illustration used for anatomical reference or procedural guidance. _figures/img_ab8c8f03afa56ebf.webp) Line chart showing 'CHANGE IN DEGREES OF CRANIOFACIAL ANGLE TO VERTICAL' (y-axis) versus 'TIME' (x-axis). The x-axis ranges from 0:00 to 3:15. The data shows an initial increase in the angle up to approximately 5 degrees around 2:00, followed by a sharp drop back to near baseline levels at 2:30. [^1]: Original PDF page 1: [[DMD Level II Unit A(2).pdf#page=1|DMD Level II Unit A(2), p.1]] [^2]: Original PDF page 2: [[DMD Level II Unit A(2).pdf#page=2|DMD Level II Unit A(2), p.2]] [^3]: Original PDF page 3: [[DMD Level II Unit A(2).pdf#page=3|DMD Level II Unit A(2), p.3]] [^4]: Original PDF page 4: [[DMD Level II Unit A(2).pdf#page=4|DMD Level II Unit A(2), p.4]] [^5]: Original PDF page 5: [[DMD Level II Unit A(2).pdf#page=5|DMD Level II Unit A(2), p.5]] [^6]: Original PDF page 6: [[DMD Level II Unit A(2).pdf#page=6|DMD Level II Unit A(2), p.6]] [^7]: Original PDF page 7: [[DMD Level II Unit A(2).pdf#page=7|DMD Level II Unit A(2), p.7]] [^8]: Original PDF page 8: [[DMD Level II Unit A(2).pdf#page=8|DMD Level II Unit A(2), p.8]] [^9]: Original PDF page 9: [[DMD Level II Unit A(2).pdf#page=9|DMD Level II Unit A(2), p.9]] [^10]: Original PDF page 10: [[DMD Level II Unit A(2).pdf#page=10|DMD Level II Unit A(2), p.10]] [^11]: Original PDF page 11: [[DMD Level II Unit 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