Fifth Stage Orthodontics Study Models
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Questions and Answers

What does the anatomic portion of the study model represent?

  • The impression of the dental arch and its surrounding soft tissue (correct)
  • The supporting stone base of the model
  • The trimmed section for aesthetic purposes
  • The overall height of the study model

What is contained in the artistic portion of the study model?

  • The aesthetically pleasing stone base supporting the anatomic portion (correct)
  • The calculations for arch expansion
  • The excess flash and bulk of the impressions
  • The measurements of the incisors

Which procedure is NOT part of the preliminary steps in model fabrication?

  • Using the wax bite to occlude the models
  • Measure the width of the maxillary incisors (correct)
  • Remove excessive bulk on the periphery of the models
  • Remove nodules on the occluding surfaces of the teeth

What does Pont's analysis primarily measure for dental arch evaluation?

<p>The width of the incisors and their relationship to arch form (D)</p> Signup and view all the answers

What is the formula to calculate the expected arch width in the premolar region?

<p>$SI x 100/80$ (D)</p> Signup and view all the answers

How is the amount of lateral expansion determined using Pont's analysis?

<p>By the difference between the expected and measured molar values (A)</p> Signup and view all the answers

What is a significant drawback of Pont's analysis when assessing dental arches?

<p>Maxillary laterals are often missing, affecting accuracy (C)</p> Signup and view all the answers

What is one of the ideal requirements for orthodontic study models?

<p>Models need to accurately reproduce the teeth and surrounding soft tissues. (B)</p> Signup and view all the answers

Which of the following is a benefit of making study models?

<p>They help motivate the patient by visualizing treatment progress. (A)</p> Signup and view all the answers

What aspect of dentition can study models help visualize?

<p>The occlusion from the lingual aspect. (A)</p> Signup and view all the answers

Why are study models necessary for medicolegal considerations?

<p>They provide a permanent record of intermaxillary relationships and occlusion. (B)</p> Signup and view all the answers

How can study models be used during treatment?

<p>To monitor changes during tooth movement. (A)</p> Signup and view all the answers

What is one of the uses of study models in assessing dental anatomy?

<p>To record intercuspation and arch form. (B)</p> Signup and view all the answers

Which requirement is crucial for the appearance of orthodontic study models?

<p>Models should have clean, smooth, bubble-free surfaces. (A)</p> Signup and view all the answers

What role do study models play if a patient needs to transfer to another clinician?

<p>They act as a reference and record of treatment. (D)</p> Signup and view all the answers

What does Total Tooth Material (TTM) refer to?

<p>The sum of the mesiodistal width of teeth from first molar to first molar (D)</p> Signup and view all the answers

How is Basal Arch Length (BAL) measured in the maxillary arch?

<p>From Downs A point to the median point on the line connecting the distal surfaces of first molars (C)</p> Signup and view all the answers

What is indicated by comparing PMBAW and PMD?

<p>The need for tooth extraction or expansion (A)</p> Signup and view all the answers

What is the correct formula to calculate the percentage of premolar diameter to tooth material?

<p>(PMD x 100) / TTM (D)</p> Signup and view all the answers

Wayne A. Bolton's analysis focuses on achieving a balance between which elements?

<p>Size of maxillary teeth and mandibular teeth (D)</p> Signup and view all the answers

What does the Premolar Basal Arch Width (PMBAW) measure?

<p>Width at the apical base between canines (B)</p> Signup and view all the answers

Which measurement is taken from Downs B point in the mandibular arch?

<p>Basal arch length (B)</p> Signup and view all the answers

What is the significance of TTM in orthodontics?

<p>Assists in planning tooth extractions and expansions (A)</p> Signup and view all the answers

What is the overall ratio of the mesiodistal widths of the 12 mandibular teeth to the 12 maxillary teeth according to Bolton analysis?

<p>91.3% (B)</p> Signup and view all the answers

If the anterior ratio is greater than 77.2%, what action does Bolton prefer to take?

<p>Reduce tooth material in the upper arch. (D)</p> Signup and view all the answers

In what population was the Bolton analysis conducted, leading to potential limitations in its applicability?

<p>A specific population group (B)</p> Signup and view all the answers

How is the anterior ratio calculated?

<p>Sum of mand. 6 x 100 ÷ sum of max. 6 (C)</p> Signup and view all the answers

What is the main focus of Carey's analysis?

<p>To determine the arch length-tooth material discrepancy (C)</p> Signup and view all the answers

What is the technique recommended for reducing excessive tooth material in the upper arch?

<p>Proximal stripping (A)</p> Signup and view all the answers

What is the anterior distance measured to determine arch length in Carey's analysis?

<p>Anterior to the first permanent molar (D)</p> Signup and view all the answers

What is a potential drawback of Bolton analysis related to maxillary canines?

<p>Ignores sexual dimorphism (B)</p> Signup and view all the answers

What is the estimated width of the maxillary canine and premolar in one quadrant based on the given formula?

<p>$ rac{Mesiodistal ext{ width of four lower incisors}}{2} + 11$ (A)</p> Signup and view all the answers

In what way does the Kesling diagnostic set-up assist clinicians?

<p>It allows visualization of tooth movements. (A)</p> Signup and view all the answers

What is one of the primary uses of the diagnostic set-up mentioned in the content?

<p>To visualize the effects of extraction on occlusion. (C)</p> Signup and view all the answers

Which of the following statements is TRUE regarding the estimated width of mandibular canine and premolar?

<p>It is calculated as $+ rac{Mesiodistal ext{ width of four lower incisors}}{2} + 10.5$. (A)</p> Signup and view all the answers

How can the diagnostic set-up serve as a motivational tool for patients?

<p>By showing proposed improvements in tooth positions. (C)</p> Signup and view all the answers

What is the first step in determining arch length using wire according to Carey's analysis?

<p>Place the wire touching the mesial aspect of the first permanent molar. (C)</p> Signup and view all the answers

What adjustment is indicated if the arch length discrepancy is between 2.5 to 5 mm?

<p>Extraction of the second premolar. (A)</p> Signup and view all the answers

What is the purpose of a mixed dentition analysis?

<p>To evaluate the amount of space available for permanent teeth. (B)</p> Signup and view all the answers

Which of the following describes Moyer's mixed dentition analysis?

<p>It uses measurements of mandibular incisors to predict space requirements. (A)</p> Signup and view all the answers

In Carey's analysis, what is done if the arch length discrepancy is greater than 5 mm?

<p>Extraction of the first premolar is usually required. (D)</p> Signup and view all the answers

When determining arch length, if the anterior teeth are proclined, where should the wire be passed?

<p>Along the cingulum of anterior teeth. (B)</p> Signup and view all the answers

Which method is NOT part of the strategic categories for mixed dentition analysis?

<p>Measuring occlusal surface wear. (A)</p> Signup and view all the answers

What is typically measured to determine the discrepancy in arch length?

<p>Width of all teeth anterior to the first molars. (B)</p> Signup and view all the answers

Flashcards

Study Models

Accurate plaster reproductions of teeth and surrounding soft tissues, used for diagnosing occlusion and dentition.

Orthodontic Study Model Requirements

Accurate reproduction of teeth and surrounding tissues, symmetrical and pleasing, clear view of occlusion from below, consistent with design measurements, smooth, glossy, and marker-proof.

Treatment Planning

Using study models to plan a course of action for correcting dental issues.

Visualizing Occlusion

Examining the way upper and lower teeth meet by looking at the models.

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Intermaxillary Relationships

The positions of the upper and lower jaws in relation to each other.

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Study Model Uses

Assessment of dental anatomy, intercuspation, arch form, curves of occlusion; evaluating occlusion with articulators; measuring treatment progress; detecting abnormalities; calculating space discrepancies.

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Patient Motivation

Study models can help patients visualize and understand their dental treatment, thus improving their commitment.

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Treatment Evaluation

Using study models to compare a patient's dental condition before, during, and after treatment.

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Anatomic Portion of Study Model

Actual impression of the dental arch and surrounding soft tissues.

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Artistic Portion of Study Model

Stone base supporting the anatomic portion, shaped for aesthetic appeal.

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Pont's Analysis

Method to estimate arch width based on maxillary incisor measurements.

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Maxillary Incisor Measurement (SI)

Greatest width of maxillary incisors, measured in millimeters.

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Measured Premolar Value (MPV)

Distance between upper first premolars.

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Calculated Premolar Value (CPV)

Estimated premolar region width, using formula based on incisor measurement.

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Model Analysis Procedure

Method to analyzing dental models by comparing measured and calculated width in premolar and molar regions.

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Model Trimming Procedures

Preliminary actions to prepare study models for analysis, like removing excess material and nodules.

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Total Tooth Material (TTM)

The sum of the mesiodistal width of all teeth from the first molar to the first molar, including the molars themselves, measured on dental casts.

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Basal Arch Length (BAL)

The distance from a reference point on the midline of the upper or lower jaw to the distal surface of the first molar, measured along the occlusal plane.

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Premolar Diameter (PMD)

The width of the dental arch measured at the top of the buccal cusp of the first premolar.

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Premolar Basal Arch Width (PMBAW)

The width of the apical base of the jaw measured from the canine fossa on one side to the other, about 8mm below the interdental papilla.

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What is the formula for "Percentage of Premolar Diameter to Tooth Material"?

(PMD x 100) / TTM

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What is the formula for "Percentage of Premolar Basal Arch Width to Tooth Material"?

(PMBAW x 100) / TTM

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What is the formula for "Percentage of Basal Arch Length to Tooth Material"?

(BAL x 100) / TTM

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What does Bolton's analysis help determine?

Bolton's analysis helps determine the disproportion between the size of the maxillary and mandibular teeth, to plan the best treatment for ideal interdigitation, overjet, overbite, and alignment of teeth.

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Bolton Analysis

A method to assess tooth size discrepancies between the upper and lower arches by comparing the sum of mesiodistal widths of maxillary and mandibular teeth.

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Overall Ratio

The ratio of the sum of mesiodistal widths of 12 mandibular teeth to the sum of 12 maxillary teeth, ideally 91.3%.

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Anterior Ratio

The ratio of the sum of mesiodistal widths of 6 mandibular anterior teeth to the sum of 6 maxillary anterior teeth, ideally 77.2%.

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Excess Tooth Material

When the overall ratio or anterior ratio exceeds the ideal percentage, indicating more tooth material in the lower arch.

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Carey's Analysis

A method to assess the discrepancy between arch length and tooth material, primarily in the lower arch.

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Arch Length

The measured distance along the lower arch, from one first molar to the other, determined using a soft brass wire.

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Arch Perimeter Analysis

Similar to Carey's analysis, but applied to the upper arch, assessing the discrepancy between arch length and tooth material in the upper arch.

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Malocclusion

A misalignment or improper fit of the teeth, often due to a discrepancy between arch length and tooth material.

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Tanaka and Johnson Formula

A formula used to estimate the width of maxillary and mandibular canines and premolars based on the width of the lower incisors.

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Kesling Diagnostic Set-up

A replica of a patient's teeth and surrounding structures made from trimmed study models, used for simulating tooth movements and treatment planning.

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Uses of Kesling Diagnostic Set-up

Aids in visualising tooth size discrepancies, determining extraction needs, simulating the effect of tooth movement, and motivating patients by showing them potential improvements.

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Tooth Size-Arch Length Discrepancy

The difference between the amount of space available in the dental arch and the total width of the teeth.

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Motivation in Orthodontics

Encouraging patients to complete treatment by showing them the expected improvements and involving them in the planning process.

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Wire Placement in Carey's Analysis

The wire is positioned along the mesial side of the lower first permanent molar, then follows the buccal cusps of premolars, incisal edges of anteriors, and finally continues along the mesial side of the first molar on the opposite side.

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Arch Length Measurement

In Carey's analysis, the arch length is determined by placing a wire along the cingulum of proclined anterior teeth or the labial surface of retroclined anterior teeth.

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Tooth Material Measurement

Total tooth material is calculated by summing the mesiodistal widths of all teeth anterior to the first molars.

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Arch Length Discrepancy

The difference between the measured arch length and the total tooth material.

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Carey's Analysis: 0-2.5mm Discrepancy

A discrepancy of 0 to 2.5 mm suggests minimal tooth material excess, which can be addressed through proximal stripping.

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Carey's Analysis: 2.5-5mm Discrepancy

A discrepancy between 2.5 and 5 mm indicates the need for extraction of the second premolar.

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Carey's Analysis: >5mm Discrepancy

When the discrepancy exceeds 5 mm, extraction of the first premolar is typically required.

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Mixed Dentition Analysis Purpose

To assess the space available in the arch for the upcoming permanent teeth, helping with space management and necessary occlusal adjustments.

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Study Notes

Fifth Stage Orthodontics Study Models

  • Study models are accurate plaster reproductions of teeth and surrounding soft tissues
  • They're essential diagnostic records, used to study occlusion and dentition in three dimensions
  • Ideal models accurately reproduce teeth and surrounding soft tissues
  • Models should be trimmed for symmetry and aesthetics, showing any asymmetrical arch forms clearly
  • Models should be trimmed to show dental occlusion when placed on their backs
  • Models should replicate proposed trimming measurements and angles
  • Models must have smooth, bubble-free surfaces with sharp angles at joins
  • Finished models should have a glossy, stain-resistant finish

Why Study Models Are Used (Benefits)

  • Invaluable for treatment planning, as they're the only three-dimensional records of a patient's dentition
  • Allow visualization of occlusion from the lingual aspect
  • Provide a permanent record of intermaxillary relationships and occlusion at the start of treatment, important for legal considerations
  • Serve as a visual aid for monitoring tooth movement during treatment
  • Help motivate patients by showing treatment progress
  • Act as a reference for comparison at the end of treatment and for post-treatment changes
  • Remind patients and parents of the original condition at the start of treatment
  • Important records in case of patient transfer to another clinician

Uses of Study Models

  • Assess and record dental anatomy
  • Assess and record intercuspation
  • Assess and record arch form
  • Assess and record occlusion curves
  • Evaluate occlusion using articulators
  • Measure treatment progress
  • Identify abnormalities, such as localized enlargements or arch distortions
  • Calculate space requirements/discrepancies
  • Provide records from before, immediately after, and several years following treatment
  • Study treatment procedures and stability

Parts of Study Models

  • Anatomic Portion: The part that shows the actual impression of the dental arch and its surrounding soft tissue structures. It must be preserved during trimming.
  • Artistic (or Architectural) Portion: The stone base that supports the anatomic portion. The shape is trimmed to make the overall form of the dental arch clear and easy to view.

Study Model Fabrication and Trimming

  • Remove any excess flash or excessive bulk from the model's edges
  • Remove any nodules present on the occlusal surfaces of the model's teeth
  • Remove any extensions in posterior areas of the model
  • Use a wax bite to occlude the model

Model Analysis (Pont's Analysis)

  • Pont's analysis uses measurement of maxillary incisors to estimate the width of the premolar and molar regions in a dental arch
  • This helps estimate the amount of expansion required when malocclusion is present

Model Analysis (Other Analyses)

  • Other analyses (Linder Harth, Korkhaus, Ashley Howe) refine the process to account for more teeth and factors influencing arch dimensions. These formulas may include measurements of premolars, total tooth material (TTM), maxillary and mandibular incisors, and canines/premolars

Drawbacks of Pont's Analysis

  • Maxillary lateral incisors are commonly missing, prone to morphogenetic alteration.
  • It does not take into account skeletal relationships or the relationship of teeth to supporting bone
  • Different populations may require additional adjustments; not just based on a numerical index

Mixed Dentition Analysis

  • Moyer's: Predicts space needs based on the correlation between the sizes of mandibular incisors and other teeth, using the amount of space for each position
  • Tanaka and Johnson: Simplified Moyer's 75% predictor table, proposing a formula to calculate the dimensions of canines and premolars
  • Includes using a mixed dentition analysis to figure out space for permanent teeth eruption and subsequent adjustments

Carey's Analysis

  • Carey's uses arch length and tooth material to identify discrepancies, usually with the lower arch, to assess treatment planning requirements such as tooth extraction, or occlusal adjustmnets

Kesling Diagnostic Set-up

  • A tool to plan treatment by creating a simulation of various tooth movements

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Description

This quiz covers the importance and specifications of study models in orthodontics. Learn about their role in treatment planning, occlusion visualization, and the necessary characteristics for an ideal model. Enhance your understanding of how these models are essential diagnostic tools in three-dimensional analysis.

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