HARD TISSUE ASSESSMENT AND DENTAL CHARTING

Learning Objectives

• You will learn what occlusion is and understand related dental terms.

• You will compare the different ways we classify misaligned bites (malocclusions).

• You will also discuss common problems that can happen because of how teeth bite together.

Occlusion

• Occlusion means how your upper and lower teeth meet when your jaws are fully closed.

• It also describes the relationship between individual teeth within the same arch.

• Centric Occlusion is the most common and comfortable way your top and bottom chewing surfaces meet.

• Important Terms for Occlusion:

  • Overjet: This measures the horizontal distance between the front surface of your lower front teeth and the biting edge of your upper front teeth.

  • Overbite: This measures how much your upper front teeth vertically overlap your lower front teeth.

  • We can describe overbite as normal, moderate, or severe.

• Centric Relation: This is the ideal position of your lower jaw (mandible) relative to your upper jaw (maxilla).

• In this position, the jaw joints (condyles) are in their most stable and relaxed position at the back and top of their sockets (fossae).

• Occlusal Disharmony means your bite is not aligned correctly.

• This can cause pain and damage to your teeth or supporting structures (occlusal trauma).

• It also increases risks for a periodontium (the tissues supporting your teeth) that is already unhealthy.

Overjet vs. Overbite: A Simple Way to Understand

• Overjet is a horizontal measurement, looking at how far your upper front teeth stick out in front of your lower front teeth.

• Overbite is a vertical measurement, looking at how much your upper front teeth cover your lower front teeth.

• A normal overbite usually means the vertical overlap is balanced.

Different Levels of Overbite

• Normal Overbite: This is when your upper front teeth overlap your lower front teeth by a healthy amount, usually with enough space.

• Moderate Overbite: The overlap is noticeable, and it might cause some symptoms or issues.

• Severe Overbite: The overlap is very significant and can cause serious problems for all your teeth and jaw.

Malocclusion (Misaligned Bite)

• Malocclusion simply means your teeth and jaws are not positioned correctly.

• It is a deviation from the perfect way your teeth should meet in centric occlusion.

• How Malocclusion Impacts You:

  • It affects your bite, making it harder to chew food properly.

  • It can make it difficult to clean your teeth well, increasing plaque.

  • It might affect how you speak.

  • It can also impact your facial appearance.

• **Types of Malocclusion (Angle's Classifications):
  **

  • Class I:

    • In this type, the biting relationship of your molars is considered correct.

    • Specifically, the front-outside cusp (MB cusp) of your upper first molar lines up with the front-outside groove (MB groove) of your lower first molar.

  • Class II:

    • In this type, your upper teeth or jaw are positioned too far forward compared to your lower jaw.

    • Specifically, the upper canine tooth lines up with the back half of the lower canine or the front half of the lower first premolar.

  • Class III:

    • In this type, your lower teeth or jaw are positioned too far forward compared to your upper jaw.

    • This often causes issues with how your front teeth line up, such as crowding or gaps.

More Details on Malocclusion Classifications

• Class I Malocclusion:

  • Even with a correct molar relationship, you can still have other bite problems, such as:

  • Crowding, where there isn't enough space for all your teeth.

  • An open bite, where some front or back teeth don't meet when you close your mouth.

  • An end-to-end bite, where front or back teeth meet edge-to-edge instead of overlapping.

  • A crossbite, where some upper teeth bite inside the lower teeth.

• Class II Malocclusions:

  • People with Class II malocclusion often have a retrognathic facial profile, meaning their lower jaw looks like it sits back.

  • Class II Division 1: Your upper front teeth visibly stick out (protrude) forwards compared to your lower front teeth.

  • Class II Division 2: One or more of your upper central front teeth are tilted significantly backward or inwards towards your tongue (retruded).

• Class III Malocclusion:

  • This is defined by the lower jaw being positioned too far forward.

  • Specifically, the front-outside groove of your lower first molar is located in front of (mesial to) the upper first molar, which indicates a particular bone structure of the jaws.

Why Dental Care for Malocclusion is Important

• Risks Involved if Malocclusion is Not Addressed:

  • You have an increased risk of occlusal trauma, which is injury to your teeth and surrounding tissues from excessive biting forces.

  • It can be harder to keep your mouth clean, leading to poor oral hygiene.

  • There is a greater risk of periodontal (gum) disease.

  • You might experience pain in your jaw joint, known as temporomandibular joint (TMJ) pain.

Basic Concepts of Primary (Baby) Teeth Occlusion

• Terminal Plane: This describes the ideal way the back surfaces of primary molars line up when baby teeth are in centric occlusion.

• Flush Terminal Plane: This is when the back surfaces of your upper and lower primary second molars meet perfectly edge-to-edge.

• Mesial Step: This occurs when your lower primary second molar is positioned further forward (mesial) than your upper primary second molar.

Parafunctional Habits (Bad Oral Habits)

• These are habits that involve your mouth but are not related to normal functions like chewing or speaking.

• Examples include clenching your teeth, grinding your teeth (bruxism), thumb or finger sucking, and rocking of your teeth.

Trauma from Occlusion (Bite-Related Injury)

• Primary Trauma: This type of injury occurs to the tissues supporting your teeth (periodontium) because of excessive biting forces.

• This happens even when your periodontium is otherwise healthy and not changed by disease.

• Secondary Trauma: This type of injury occurs when normal or even excessive biting forces damage a periodontium that is already weakened by disease.

Review of Key Dental Terms and Concepts

• Labioversion: A tooth is positioned too far towards the lips (labial side) from its normal place.

• Linguoversion: A tooth is positioned too far towards the tongue (lingual side) from its normal place.

• **Descriptions of Tooth Tilting:
  **

  • Distal Tipping: A tooth is angled backwards (distally).

  • Mesial Tipping: A tooth is angled forwards (mesially).

  • Lingual Tipping: A tooth is angled towards the tongue (lingually).

  • Labial Tipping: A tooth is angled towards the lips (labially).

  • Mesial/Distal Displacement: The entire tooth has moved either forwards (mesially) or backwards (distally).

  • Infraversion: A tooth is positioned below its normal biting level.

  • Supraversion: A tooth is positioned above its normal biting level.

  • Rotation: The tooth itself has rotated around its long axis.

  • Transposition: Two teeth have switched places or are in completely the wrong position in the arch.

Different Ways Anterior (Front) and Posterior (Back) Teeth Can Meet

• Anterior Edge-to-Edge: Your upper and lower front teeth meet directly edge-to-edge instead of the upper teeth slightly overlapping the lower ones.

• Posterior End-to-End: Your upper and lower back molars meet directly cusp-to-cusp, rather than fitting into each other in a specific bite.

• Crossbite: This is when one or more upper teeth bite inside the lower teeth.

  • It can happen at the front of your mouth (anterior crossbite).

  • It can affect only one side (unilateral crossbite).

  • It can involve just a single tooth.

Why This Matters for Explaining to Patients

• Understanding these detailed principles and classifications of how teeth bite (occlusion) and misaligned bites (malocclusion) is crucial.

• It helps dental professionals clearly explain to patients how their dental alignment impacts their overall oral health and why certain treatments might be necessary.