ortho 3rd year

What are common symptoms of TMJ disorder?

Jaw pain (especially near ears), clicking/popping/grinding sounds, difficulty opening or closing the mouth, headaches or earaches.

What are the main purposes of TMJ & bruxism appliances?

Protect teeth, reduce muscle hyperactivity, stabilize occlusion, decompress the TMJ.

What are the two main types of appliances for TMJ/bruxism?

Night guards and day guards.

What are the types of night guards?

Hard acrylic, soft/thermoplastic, dual laminate (soft inside, hard outside), and digital CAD/CAM–fabricated guards.

What is the Mount Sinai / Gelb appliance designed for?

Daytime clenching management with a lower profile that allows speaking.

What factors determine appliance selection?

Level of grinding, severity of wear, patient compliance (day vs. night wear), and comfort.

What is required for appliance fabrication?

Maxillary and mandibular impressions/scans, and bite registration.

What are the steps in the digital workflow for night guard fabrication?

Intraoral scan → digital design (CAD) → milling/3D printing → delivery and adjustment.

What causes TMJ clicking or popping?

Disc displacement within the TMJ, often when the disc moves out of alignment and then snaps back into place.

What is bruxism?

Involuntary grinding or clenching of teeth, usually during sleep but can also occur during the day.

What are common signs of bruxism visible to a clinician?

Wear facets, flattened cusps, fractured enamel, muscle hypertrophy (especially masseter), and tongue/cheek scalloping.

How do night guards help reduce muscle hyperactivity?

They alter occlusal feedback and reposition the jaw slightly, reducing clenching intensity.

Why might a hard acrylic guard be chosen over a soft guard?

Hard guards provide more stable occlusion, last longer, and are better for heavy grinders.

Why might a soft or thermoplastic guard be chosen?

They are more comfortable and better for mild bruxism, though they may encourage chewing in some patients.

What is the advantage of a dual-laminate night guard?

Soft interior improves comfort; hard exterior improves durability and occlusal stability.

What is a key advantage of CAD/CAM-fabricated guards?

Superior fit, reproducibility, reduced chairside adjustment, and digital backup for easy remakes.

Why is patient compliance important when selecting an appliance?

Treatment success depends on consistent wear—no appliance works if the patient won’t wear it.

What is bite registration used for in appliance fabrication?

To capture the patient’s jaw relationship and ensure correct occlusal contacts on the appliance.

Why must impressions or scans capture the full dental arches?

The entire occlusal scheme must be evaluated to design a properly functioning guard.

What is a major benefit of the digital workflow compared to conventional?

It eliminates distortion from impression materials and stone, improving accuracy.

What is “decompression” of the TMJ?

Slightly separating the joint surfaces to reduce pressure on the articular disc and surrounding structures.

Why might a patient need a daytime appliance rather than only a night guard?

Daytime clenching (awake bruxism) contributes significantly to muscle fatigue and joint pain.

What makes the Gelb appliance suitable for daytime use?

Its low profile permits talking and light function without bulkiness.

What commonly triggers TMJ muscle hyperactivity?

Stress, sleep disturbances, poor posture, malocclusion, or parafunctional habits

Why do dentists sometimes avoid soft guards for heavy bruxers?

Soft guards can increase clenching intensity because they provide a “chewy” resistance.

What symptoms suggest a poorly adjusted night guard?

Jaw soreness, new headaches, uneven contacts, shifting of teeth, or difficulty closing comfortably.

What is the ideal vertical opening for a bite registration?

Approximately 2–3 mm.

What does CR stand for, and why is it ideal for bite registration?

Centric Relation—ideal because it represents the most stable, reproducible condylar position.

What does CO stand for, and why is it often used?

Centric Occlusion—most commonly used because it represents habitual bite.

What materials are commonly used to take bite registrations?

Wax and Vinyl Polysiloxane (VPS).

What are common types of vertical stops on articulators?

Thumb screw and anterior pin.

What type of articulator is most commonly used for night guard fabrication?

Hinge articulator.

Which articulator is closest to the patient’s true TMJ movement?

Semi-adjustable articulator.

What is the benefit of using a semi-adjustable articulator?

Less intraoral adjustment is needed.

How should the model be outlined on the facial surface for fabrication?

2–3 mm cervical to the incisal edges and cusp tips.

How far past the gingival margins should the outline extend on the lingual surface?

1–2 mm past the gingival margins.

What should you do if no bite registration is provided?

Open vertical (mount in CR and open the bite).

How much space should exist from the lowest maxillary cusp tip to the opposing arch when opening vertical?

2–3 mm.

What must be checked before proceeding with fabrication?

No interferences in excursions.

How thick should the wax-up of the night guard be?

Uniform 2–3 mm thickness.

Which teeth must be included in the night guard coverage?

All teeth on the arch that will be wearing the splint.

How many occlusal contacts should each opposing tooth have?

At least one contact.

Why are ramps created for the canines?

To disclude the posterior teeth during lateral excursive movements.

What must be ensured before processing the night guard in a flask?

There must be no undercuts.

What mixing ratio is recommended for IMPAK material?

6 mL liquid to 20 cc powder.

How long and at what temperature should IMPAK be cured?

1 hour in 100°C (boiling water).

What should be adjusted during trimming with articulating paper?

Ensure all teeth contact evenly and simultaneously.

Should the canine-guided ramps be trimmed away?

No — they must be preserved

What thickness should the facial surface of the finished appliance be?

1.5–2 mm, scalloped around posterior teeth.

What thickness should the lingual surface be?

1.5–2 mm uniformly throughout.

What setting should be used when polishing the night guard?

Low speed with even pressure in occlusion.

What must be maintained during polishing?

Intact occlusal contacts.

What is the first step when bending a fence?

Bend the wire in an M shape, starting with the center loop.

How much shorter should the side loops be when bending a fence?

Approximately 2 mm shorter than the center loop.

At what angle should the tags be bent relative to the fence?

~45°, parallel to the palate (within 1 mm accuracy).

To what dental surfaces must the fence be parallel?

The lingual surfaces of the maxillary anteriors, curved from canine to canine (3–3).

What retentive feature is added to the fence?

Curly-Q retentive tags.

For a fence with an opposing arch, where should the fence sit?

Just occlusal to the cingulums of the lower central incisors.

For a fence without an opposing arch, how far should it extend?

2 mm past the incisal edge of the upper central incisors.

For a fence without an opposing arch, how should the lateral loops be adjusted?

They should be 2 mm shorter.

In one-step acrylic processing for a removable fence, how is the wire positioned?

Suspended over the palate using utility wax.

What can be done to prevent acrylic locking around the fence tines during one-step processing?

Block out the occlusal of the fence tines with wax before sprinkling acrylic.

What should you avoid during one-step acrylic processing of a fence?

Do NOT bury the fence in acrylic.

What are the finishing steps after processing a removable fence in acrylic?

Trim the acrylic around the fence carefully, then trim and polish.

In the two-step acrylic method, what is done first?

Sprinkle and cure the acrylic without including the fence

What step is added during the second stage of two-step processing?

Trim a groove in the acrylic where the fence will sit.

How is the fence attached during the second step of two-step processing?

Placed into the groove as an acrylic repair.

What fabrication method is typically used for a fixed habit breaker?

Spot welding and soldering to create various fence designs.

What is a “Blue Grass” habit breaker?

A habit-breaking device featuring a roller or bead that the patient manipulates with their tongue to discourage habits.

Can habit breakers be incorporated into other appliances?

yes, they can be integrated into appliances such as Hawley retainers or other orthodontic frameworks.

What is the purpose of a habit breaker appliance?

To interrupt and discourage oral habits (usually thumb sucking or tongue thrusting).

What does proper fence placement ensure in habit breakers?

That the patient cannot position the tongue or digit in the habit-forming location

What should you check for during the first inspection of the model for an Essix retainer?

Undercuts, discrepancies, positive bubbles, and any areas needing blockout.

Why must the path of insertion/removal be easy for the patient?

To prevent the Essix material from cracking.

Why should the base of the stone model not be too high?

A high base prevents proper adaptation of the Essix material.

What is the purpose of creating an undercut in the model base?

To increase suction and improve the adaptation of the Essix during vacuum forming.

What base modification shape is most commonly used for suction?

A horseshoe shape.

What is an alternative method to improve suction besides a horseshoe cut?

Creating a hole in the center of the model.

What should be done before vacuum forming to prepare the stone model?

Air-blow all debris; optionally apply a very thin separator coat.

How do you know the Essix sheet is ready to form?

When it slumps about 1/3 of the way down.

What happens if the Essix sheet slumps too much?

It becomes too thin and develops excess lines.

When should you turn on the vacuum during forming?

Just before the Essix reaches its correct slump depth.

How long should vacuum suction be maintained?

Approximately 30 seconds.

What should be done if the model is still hot after forming?

Place it under cold water.

How close should you trim the Essix to the gingival margins on the facial/buccal surfaces?

1–2 mm from the gingival margins.

How close should you trim the lingual portion of the Essix?

3–4 mm from the gingival margins.

Where should the final trimmed Essix margin sit on the buccal surface?

0.25 mm above or below the gingival margin, neatly scalloped.

What is the main advantage of mesh pads on a 3×3 retainer?

They provide exact bond placement.

What materials can mesh pads be made from?

Soldered metal mesh or acrylic.

How can bonding retention be improved for a straight-wire 3×3?

By sandblasting the enamel before bonding.

Why does braided wire not require retention features?

The braided texture provides its own mechanical retention.

What is the primary advantage of a V-loop design in bonded retainers?

Allows the patient to floss around the wire

What are disadvantages of V-loop retainers?

Difficult to bend, expensive, and sometimes uncomfortable.

How far should the bonding matrix extend past the incisal edges on the labial surface?

No more than 1–2 mm.

Where should the lingual margins of the matrix finish?

At or 1 mm below the gingival margins

Besides retention, what is another clinical use for bonded wires?

Splinting mobile teeth.

Name causes of tooth mobility that may require splinting.

Periodontal disease, trauma (e.g., luxation or root fracture), and post-surgical stabilization.

What are the main components of a Nance appliance?

Molar bands, a wire passing bilaterally over the rugae area, and an acrylic button.

Why must the acrylic button on a Nance appliance be sufficiently large?

To distribute force evenly over the palatal tissue.