Unit 308 – Provide support during the stages of prosthetic treatments Assessment Answer Help

City & Guilds Level 3 Extended Diploma in Dental Nursing

Unit 308 Aim

So that the learner can be able to acquire the knowledge and skills to learn about the variety of fixed and removable appliances, when and how they are applied in the field of dentistry. Another component that is reflected by this unit is the ability of the learner to practically present the skills and knowledge of how to prepare the clinical environment during the stages of fixed and removable prostheses, and how to give the proper support.

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308 1.1- Explain the difference between fixed and removable prostheses, also including why they are used in dentistry.

Answer: 

Prostheses are employed in the dentistry field to mimic the missing teeth and restore the functionality and appearance of the mouth cavity. Dental prostheses are of two types: the fixed and removable ones.

Fixed Prostheses

Fixed prostheses are cemented on the teeth or implants and cannot be removed by the patient. They include:

• Crowns- These are types of caps that are fitted on a damaged tooth or implant.
• Bridges: It is performed to restore one or more missing teeth through bridging the space between two or more existing teeth or implants.
• Veneers: These are shells that are bonded to the front of the teeth to enhance their beauty.
• Implants: These are artificial roots of the teeth which are implanted into the jawbone.

Removable Prostheses

The removable prostheses can be removed and replaced by the patient in the mouth. They include:

• Complete Dentures: These are the ones that substitute all the teeth in the lower or upper jaw.
• Partial Dentures: These are used to replace 1 or more missing teeth that are fixed in place with the help of a clasp that fits on the remaining teeth.
• Overdentures: Overdentures are a form of denture which is fitted on the existing teeth or implants.

Why are they applicable to Dentistry?

Prostheses in dentistry are used with the main aim of restoring the functions and appearance of the mouth cavity. They help in:

• Chewing: Prostheses can assist in restoring the proper function of being able to chew food.
• Speech: They can enhance speech loss due to the loss of teeth.
• Esters: Prostheses enhance the looks of the mouth and face that may lift the self-esteem of the patient.
• Prevention of additional tooth loss: They can prevent the remaining teeth to drift in the gap caused by the absence of teeth.

It is based on the following factors to decide between fixed and removable prosthesis: the quantity and position of missing teeth, the condition of remaining teeth and gums, the general health of the patient and the preference of the patient.

308 – 1.2 Describe fixed prosthetic treatments available to replace missing teeth.

Answer:

A. Implants

A dental implant refers to a fixed form of prosthesis, which replaces one or more lost teeth. The implant is a titanium screw that is inserted into the alveolar bone surgically, where it is used as an artificial root of the tooth. Gradually, the implant becomes part of the surrounding bone by a mechanism known as the process of osseointegration. After healing, an abutment is fitted to the implant, and a crown is placed on top of it to restore the functionality and the appearance.

The problem of implant is extensively used in contemporary dentistry and is a part of the professional guidance provided in the UK by such organisations as the General Dental Council to guarantee proper training and safety of patients.

The primary benefits of the implants are that adjacent teeth are not compromised (since no preparation is needed), it helps in preventing bone resorption, provide good aesthetics and have a long life span. They are very stable and operative, just like a natural tooth.

Implants, however, necessitate adequate bone volume and good oral health. They are costlier than other fixed alternatives and require slight oral surgery. The full healing process may also require a few months, and the final crown can be laid. Patients with uncontrolled systemic conditions or poor oral hygiene and heavy smokers may not be appropriate to be fitted with implants.

308– 1.2 Describe fixed prosthetic treatments available to replace missing teeth.

Answer:

A. Bridges

Dental braces are cemented artificial teeth that are employed to restore one or more lost teeth. A bridge is made by fixing an artificial tooth (pontic) between the teeth that are close to it, the so-called abutments, which also provide the support. Bridges also replace aesthetics, functionality and eliminate drifting of the neighbouring teeth. They are usually offered in general practice under the direction of the General Dental Council in order to make sure that the treatment is planned in a safe and correct manner.

i) Traditional Retainer / Pontic Bridge.

The traditional type of bridge would have one or more retainers (crowns) positioned on the ready abutment teeth, and a pontic suspended between them to carry out the missing tooth. The abutment teeth are trimmed to create room where full coverage crowns are to be placed.

The benefits are good retention, longer lasting, and they can be used in the posterior teeth, where the forces are higher. It gives good aesthetics in the case of porcelain-fused-to-metal or ceramic material.

Several of the disadvantages are that huge amounts of healthy tooth tissue must be removed from abutment teeth, and it may cause pulpal damage. When one of the abutments is not doing well, the rest of the bridge might have to be replaced.

ii) Adhesive (Maryland) Bridge

A Maryland Bridge is an adhesive bridge, where the wings are made of metal or ceramic bonded to the palatal surfaces of the teeth adjacent to one another to hold the pontic. Minor preparation of teeth is needed.

The benefits are structural preservation of teeth, shorter treatment time and better aesthetics, especially in anterior teeth.

These are disadvantages such as increased risk of debonding and low appropriateness in high-bite force areas.

308-1.3 Describe why a clinician may choose to carry out a preparation for a permanent restorative fixed prosthesis.

Answer:

• Jacket Crown (Anterior and Posterior): A jacket crown is a kind of full coverage dental restoration which is fitted over the whole tooth surface to enhance its appearance and effectiveness. It is applied in case of severe damage or decay of the tooth or a non-aesthetically pleasing look.
  
  
• Post Crown: Post crown is employed when there is insufficient tooth structure to support a conventional crown. The tooth is supported by placing a post in the root canal.
  
  
• Veneer: A veneer is a thin layer of porcelain or composite material that has been applied over a tooth to enhance its appearance or shield it against damage. It is applied in case of minor defects of the tooth, like discolouration, chips, or slight misalignment.
  
  
• Inlay / Onlay: Inlays and onlays are applied in instances when the tooth has suffered too much damage to support filling, and not enough damage to support a crown. These are applied in order to replace the shape of the tooth and stop the damage or decay.

308 1.4 Explain the use of equipment, instruments, burs and materials during the preparation of a permanent restorative fixed prostheses.

Answer:

Preparation of a permanent restorative fixed prosthesis requires multiple steps and the use of multiple pieces of equipment, instruments, burs, and materials. Here's a brief overview:

Equipment and Instruments

• Dental Handpiece: This is a rotating tool at high speed, which is applied in cutting and shaping the tooth structure. It is commonly applied to different burs.
  
  
• Mouth Mirror: It is utilised to give indirect sight, reflect and retract the light into the oral cavity.
  
  
• Explorer: This will be used to find cavities or other complications in the tooth structure.
  
  
• Periodontal Probe: This is applied to determine the depth of pockets of a tooth to determine the health of the periodontium.
  
  
• Burs
  
  
• Diamond Burs: The burs are used in cutting and shaping the tooth structure. They are of different shapes and sizes according to their use.
  
  
• Carbide Burs: They are also helpful in cutting and shaping; however, they are not as abrasive as diamond burs.
  
  
• Materials
  
  
• Impression Materials: It is applied to create a copy of the teeth and gums of the patient to perfection. Alginate and silicone-based materials are the most widespread.
  
  
• Temporary Crown Material: It is utilised to make a temporary crown to safeguard the prepared tooth until the permanent prosthesis is made.
  
  
• Cement: This is what is applied to fix the prostheses on the tooth permanently. It comes in different varieties such as glass ionomer and resin-based cements.

308 1.5 Explain the purpose of a gingival retraction cord.

Answer:

Gingival Retraction Cord: Meaning and Significance.
Gingival retraction cord is a dental instrument that has found wide applications in dentistry, especially in restorative and prosthodontic dentistry. Its main purposes are:

• Tissue Management: The cord is put into the gingival sulcus to push or pull the gingiva off the tooth. This gives enhanced access and visibility to the tooth preparation field.
• Impression Accuracy: The cord displaces the gingival tissue, and this gives a more accurate impression of the prepared tooth and the surrounding area. This is essential in the production of restorations, including crowns and bridges.
• Hemostasis: The cord may also be used to control bleeding and crevicular fluid leakage in the sulcus that will leave a dry field to take impressions.

308-1.6 Describe the different types and purposes of temporary fixed prostheses.

Answer:

Temporary fixed prosthesis are temporary tooth restorations that protect the teeth as well as preserve aesthetics and functionality until the real prosthesis is produced. They are mostly temporary and are taken out when the permanent prostheses are available.

a) Pre-formed Temporary Crown

Ready-made, ready-to-wear crowns, which are in various shapes and sizes, are called pre-formed temporary crowns. They are crafted out of plastic or metal and are placed in cases where a tooth is made ready to have a crown. The dentist picks the size and shape that is the most appropriate, bends it to meet the prepared tooth and fixes it.

Purpose:

• Protect the prepared tooth
• Position teeth in the denture.
• Offer provisional aesthetics and functionality.

b)  Chairside Built Temporary Crown.

Temporary crowns made by Chairide are those that the dentist makes at the dental office. Acrylic resin or composite resin makes them. The dentist makes an impression of the prepared tooth and sends it to himself to build the temporary crown.

Purpose:

• Protect the prepared tooth
• Position teeth in the denture.
• Aesthetics and functionality are superior to ready-made crowns.

c)   Veneer

A temporary veneer is a thin layer made of resin material that is attached to the front side of a tooth. It is adopted in situations where a tooth is to have a veneer.

Purpose:

• Protect the prepared tooth
• Position teeth in the denture.
• Offer make-shift beauty.

d)  Inlay / Onlay

In the case when a tooth is prepared to receive an inlay or onlay, temporary inlays and onlays are applied. Acrylic resin or composite resin makes them. The dentist makes an impression of the prepared tooth and builds a temporary inlay or onlay using it.

Purpose:

• Protect the prepared tooth
• Position teeth in the denture.
• Provide temporary function

To sum up, temporary fixed prostheses are also essential in dental restorative treatment. They cover the teeth which have already been prepared, support the position of the teeth and give some temporary aesthetics and functioning.

308-1.7 Explain the equipment and materials used in the construction of a temporary fixed prosthesis.

Answer:

A. Pre-Formed Temporary Crown

Ready-made temporary crown: A temporary crown shell which can be used to cover temporarily after tooth preparation. Some of the equipment needed is the crown scissors to cut the crowns, crown contouring pliers, a mixing pad and spatula to apply cement, and articulating paper to measure the occlusion. They consist of pre-made crowns (stainless steel on the back of a tooth or polycarbonate/acrylic on the front) and temporary luting cement, including zinc oxide non-eugenol cement. The crown is chosen, cut to fit the gingival margin, adjusted, and cemented in a provisional state, allowing protection to the prepared tooth, aesthetics and elimination of sensitivity.

B. Temporary Crown Built by Chairside.

A chairside temporary crown is made right in the oratory. The equipment comprises a pre-operative impression or matrix (silicone putty), mixing gun or dispensing system, scalpel, finishing burs and polishing discs. Bis-acryl composite or acrylic resin and temporary cement are common materials that are used. The substance is inserted into the matrix and fitted on the prepared tooth and left to dry, which is then removed, trimmed, adjusted, polished and cemented.

C. Temporary Veneer

Composite resin is the material that is used to prepare temporary veneers. The equipment one needs consists of etching gel (where necessary), bonding agent (when spot bonding), curing light, finishing strips, and polishing discs. The material shields the ready labial area and does not lose aesthetics until the final veneer is installed.

D. Temporary Inlay / Onlay

Onlays and inlays are temporary restorations that are produced using acrylic or composite resin as a temporary constituent. These equipments consist of an impression or matrix, carving tools, finishing burs, and articulating paper. The restoration is formed, modified to fit into an occluding area and held in place by temporary cement to shield the opening until the permanent restoration is installed.

308 1.8 Explain the purpose of a temporary luting cement.

Answer: 

Temporary luting cement is a kind of dental cement applied in the field of dentistry in short time.

Its main purposes are:

• Provisional Restoration: It is implemented to retain a temporary crown or bridge till the permanent restoration is prepared. This enables the patient to be able to have normal functioning and appearance at this time.
• Pulpal Protection: It may be used as a protective layer between the tooth and a temporary restoration to prevent a thermal shock and chemical irritation of the pulp.
• Ease of Removal: Temporary luting cement is also easily removable since it is not intended to be used permanently and thus is removed after the final restoration is prepared.

308 1.9 Outline the advice which should be given to a patient with a temporary fixed prosthesis.

Answer:

Clear instructions on maintenance of the restoration and the preservation of the prepared tooth should be provided to patients who have a temporary fixed prosthesis (temporary crown, bridge, veneer or inlay/onlay) in place.

They need to be warned that the temporary restoration lacks strength as compared to the permanent one and should be handled with much care. The patients are not to chew hard, sticky or chewy items (toffees or chewing gum) on the side that has a temporary prosthesis, as it can dislodge or break the prosthesis. One should also not bite into hard foods.

Oral hygiene should be taken care of. The patients are to brush the surrounding area gently with a soft toothbrush and fluoride toothpaste. One should pull out interdentally around a temporary bridge as opposed to lifting upwards to avoid being pulled out.

It should be explained to patients that mild sensitivity to hot, cold or pressure is a normal occurrence, but when pain, mobility or loss of the restoration does not resolve, they should inform the dental practice as soon as possible. They will be required to visit their follow-up appointment, where a permanent prosthesis will be placed because temporary restorations are not supposed to be left in place too long, as they will either wear down or leak.

308-1.10 Explain the different types of permanent luting cements for cementation of permanent fixed prostheses.

The permanent luting cements are the ones that are permanently fitted to the teeth structure with a dental prosthesis like crowns, Veneers, inlays/onlays and braces. Permanent luting cements are available in various forms, and each form possesses distinct properties and uses.

Crown
Glass ionomer cements (GIC) and resin-modified glass ionomer cements (RMGIC) are commonly used with regard to crowns.

• Glass Ionomer Cements (GIC): Cements that are chemically attached to the structure of the tooth and release fluoride, which has the potential to prevent decay. They are, however, not as strong as other forms of cement.
  
  
• Resin-Modified Glass Ionomer Cements (RMGIC): These cements are a combination of the GIC and the durability of resin cements. They are commonly employed in crowns which need a powerful bond and good looks.

Veneer

In the case of veneers, resin cements will be employed normally because of their better aesthetic characteristics.

• Resin Cements: These are cements that offer a high bonding ability as well as good appearance. They come in varying colours to suit the natural colour of the teeth.

Inlay/Onlay

Inlays and onlays, the resin cements and RMGIC are all possible.

• Resin Cements: This provides good bonding and aesthetics. They also wear out slowly, and thus can be used in inlays and onlays where the stress is very high.
• RMGIC: Inlays and onlays, which need a high bond strength and good appearance, are frequently done with these cements.

Bridge
In the case of bridges, cement is dependent on the nature of the bridge; it could be a conventional bridge or an adhesive bridge.

(i)   Conventional Bridge
In the traditional bridges, zinc phosphate cement is commonly employed.

• Zinc Phosphate Cement: Zinc Phosphate Cement is very old, as it is the one that is said to be very strong and durable. It does not, however, chemically bond in the tooth structure and does not produce fluoride.

(ii)  Adhesive Bridge

In the case of adhesive bridges, resin cements are generally employed.

Resin Cements: These are cements that offer a high bonding ability as well as good appearance. They also wear out slowly, and thus, they can be used in adhesive bridges.

To sum up, the decision on the cement utilisation is subject to the nature of the prosthesis, the site in the mouth, the health of the tooth structure, and the aesthetic needs.

308 1.11 Describe the equipment, instruments and materials used in the fitting of a permanent fixed prosthesis.

Answer: 

Equipment and Instruments

• Dental Chair: It is the main piece of equipment on which the patient sits during the procedure.
• Dental Handpieces: The dental handpieces are applied in order to cut and shape the tooth structure. They have high and low-speed handpieces.
• Burs: These are tools that are cut with the handpieces. They are of all shapes and sizes to serve different purposes.
• Dental Mirror and Explorer: these are employed to examine and to assist in viewing the oral cavity.
• Impression Trays: These are applied to impress the mouth of the patient.
• Articulator: This is equipment that is utilised to replicate the functionality of the jaw during the generation of the prosthesis.

Materials

• Impression Materials: They are intended to create a copy of the mouth of a patient. Familiar materials are silicone and alginate.
• Dental Stone: It consists of carving an impression of the mouth of the patient.
• Dental Cement: This is applied in order to permanently fix the prosthesis to the tooth.
• Type of Prosthetic Material: The type of prosthesis may be porcelain, composite resin or metal alloys.

308-3.1- Describe the types of removable prostheses available:

A. Partial
i) Acrylic Partial
ii) Cobalt-chrome

B. Full 
C. Immediate

Answer:

Removable prostheses are dental appliances removable, which can be cleaned. They are provided to replace the missing teeth, and they are made to enhance the function and look of the patient's mouth. Here are the main types:

1. Partial Prostheses
Partially, the prostheses are applied, whereby there are still several natural teeth. They are normally fastened to the rest of the teeth using clips.

There are two main types:

• Acrylic Partial Prostheses: This is composed of a plastic substance named polymethyl methacrylate. They are normally employed as an intermediate solution because they are less durable than other materials.
  
  
• Cobalt-Chrome Partial Prostheses: These are crafted out of an alloy of metals and are hence more durable and comfortable to the patient. They are not very eye-catching like the acrylic prostheses because they are thinner and look more natural.

2. Full Prostheses

Complete dentures or full prostheses are applied when the upper or lower jaw is missing all the teeth. They consist of acrylic and have to be attached to the denture and the gums through suction.

3. Immediate Prostheses

Before the extraction of the teeth, instant prostheses are manufactured and can be fitted in the mouth immediately after the extraction. This kind of prosthesis is normally a temporary measure during the healing of the gums and bone, and as the final prosthesis is to be manufactured.

308-3.2 Explain the stages and the use of equipment, instruments and materials required when constructing a full acrylic denture.

Stages

1.    primary impressions    
2.    secondary impressions    
3.    bite (occlusal) registration    
4.     try in    
5.    retry    
6.    fit    
7.    Review

Answer:

a) Primary Impression: The initial step is taking a primary impression of the mouth of the patient with the help of a stock impression tray and alginate impression material. This gives an initial prototype of the oral cavity of the patient.

b) Secondary Impressions: A secondary impression is made in a special tray with a more detailed impression material, an elastomer impression material. This provides a fairer description of the oral tissues of the patient.

c) Bite (Occlusal) Registration: The bite of the patient is entered into the Willis bite gauge. This is to make sure that the denture will fit in and work appropriately.

d) Try In: A wax try-in denture is made, and the patient tries this denture in his/her mouth. The shade guide is applied in order to match the shade of the patient's natural teeth. They are adjusted with the help of a wax knife and a Le Cron carver.

e) Retry: The adjusted wax denture is tried once again by the patient. Any additional correction is done, and a fit is verified with the help of articulating paper.

f) Fit: The last denture is the acrylic one. The patient tests it between the lips, and any last modifications are carried out with acrylic trimming burs and a straight handpiece.

g) Review: The patient comes back to have a review appointment to ensure that the denture fits and works well. Any adjustments that are required are done.

308 3.3- Explain how the stages would differ when constructing a partial cobalt-chrome or immediate prosthesis.

Answer: 

• Preliminary Impressions: This is an impression of the mouth of a patient, which is made to form a study model as an alginate impression.
  
  
• Design: The prosthesis is planned based on the model study, taking into account such elements as the number of missing teeth, the location of remaining teeth, and the bite of the patient.
  
  
• Master Impressions and Bite Registration: It is a more precise impression of the mouth of a patient that is made and stored on a custom tray. The bite of the patient is also documented.
  
  
• Try-In: The metal frame of the prosthesis is tried in the mouth of the patient to ensure that it fits, and any required corrective measures are made.
  
  
• Addition of Acrylic: The artificial gums and teeth require the addition of the metal framework with acrylic.
  
  
• Final Fitting: The final prosthesis is incorporated into the mouth of the patient, and any final adjustments are made.

308 3.4 Describe the benefits of a cobalt-chrome partial denture when compared with an acrylic partial denture.

Answer:

A partial denture made of cobalt-chrome has a number of advantages over an acrylic partial denture. The cobalt-chrome is stronger and also more durable, which enables the denture base to be thin without compromising the strength. This leads to enhanced comfort and tolerance in the patients. It is finely fitted as it has a cast metal structure, which makes it more stable and resistant. Cobalt-chrome dentures are also more evenly distributed in the load of desired occlusal forces to the teeth that remain, which helps in protecting the structure of the mouth. Moreover, they are more hygienic, since the metal material is not as porous as acrylic, which minimises plaque.

308 3.5- Explain the additional information the patient will require when an immediate denture is fitted.

Answer:

When a patient receives an immediate denture, it is important to inform him /her of the information he or she needs to take proper care and maintenance. The following are the main points to be taken into consideration:

Learning Immediate Dentures.

Immediate dentures. This is a kind of denture, which is fitted as soon as the natural teeth have been removed. These are only a temporary measure until the gums and tissues are healed, and finally, a conventional denture is adapted.

Post-Procedure Care

Following the process, the patient must:
Do not take off the denture within 24 hours. This is used to manage bleeding, and it should be maintained until the follow-up date.
Clean the denture daily. Have a soft brush and non-abrasive denture paste.
Care should be taken with the denture so that it does not break.

Potential Issues

This patient must know about such potential problems as:
Pain and painful areas: This is observed in the initial few weeks and can be corrected during follow-up visits.
Modifications of speech and eating: These can take place at the beginning, but they will be eliminated with time and practice.

Follow-Up Appointments

Follow-up meetings should be taken regularly to:
Adjust the denture: Due to the healing of the mouth, the denture might require adjustment or relining.
Keep oral health: To check oral health and healing, one should have regular check-ups.

Change to a permanent denture.
The patient is expected to realise that he or she is using a temporary denture. After the healing process, a permanent denture will be given.

308 5.3- Summarise the use of an articulator.

Answer:

A dental articulator is a machine used in the field of dentistry. It recreates the position and movement of the mandible in relation to the maxilla, which are static and dynamic.

Key Uses of an Articulator

• Diagnosis and Treatment Planning: It assists in diagnosing different types of occlusal disorders and making the corresponding treatment plan.
  
  
•  Restorative Procedures: The procedure is applied in the creation and production of dental restorations such as crowns, bridges and dentures.
  
  
• Orthodontic Treatment: It helps in the planning and implementation of orthodontic treatment.
  
  
• Jaw Movements: It enables the researcher to study the jaw motions of the patient, which may be applied in different forms of dental treatment.
  
  
• Important Features of an Articulator: These are the features that are important about an articulator.
  
  
• Intercondylar Distance: This is the distance between the two condyles of the articulator; this must correspond to the actual intercondylar distance of the patient.
  
  
• Condylar Inclination: This angle corresponds to the condyles' position that the articulator is set to, which must be similar to the actual condylar inclination of the patient.
  
  
• Bennett Angle: It is the angle of the sideways movement of the mandible, which must align with the actual Bennett angle of the patient.