Indications and Contraindications of a Dental Crown

Crown and bridges are being served to dental patients routinely as its manufacturing has become fast, readily available. It is a dependable option. 

Although, the crown & bridge is generally considered very safe and it is associated with a low incidence of complications, there are some precautions that need to be considered. 

Indications of a Dental Crown

1. Damage of crown beyond repair
2. Large filling needing replacement
3. Fractured tooth
4. Esthetic enhancement
5. Dental implant coverage
6. To fix dental bridges or dentures
7. Erosion of teeth

1. Damage beyond repair: Cases where the tooth has been damaged beyond repair: If the patient has a large cavity that cannot be fixed with a filling, but the dentist determines that the dentine and pulp are in good condition then he will recommend that a crown be placed to save the tooth.

2. Large fillings need replacing: Fillings need replacing every so often, your dentist may recommend installing a crown instead of re-filling the tooth, the reasons for this are the crown is a long term solution and it is aesthetically more pleasing.

3. Fractured tooth: In the case that a tooth gets fractured due to a dental trauma or progressive tooth decay, it is highly recommended that a procedure known as post and core be performed. The post and core procedure simply put, is the placement of an implant without extracting the root. In this procedure a small rod is inserted into the root of the affected tooth, this rod will slightly protrude and the core or crown will be attached to it. For this procedure, the tooth in question will require a root canal before the post and core can be done.

4. Esthetic enhancement: For patients who have discoloured or uneven teeth, or even for those who have large fillings the use of crowns can greatly improve the esthetic of their smile.

5. To cover dental implants: When a patient has lost a tooth for any reason, and an implant is required to maintain proper function, the implant will be covered by a porcelain crown that has been made to match your existing teeth.

6. To affix dental bridges or dentures: A dental bridge is a prosthetic used to replace missing teeth, these bridges are permanently adjoined to either dental implants or crowned teeth. The dental crowns are used to hold the prosthetic in place.

7. Dental erosion: The tooth enamel can be dissolved by the acidity in foods; when the enamel has been compromised, porcelain crowns are the ideal solution to prevent the progression of tooth decay to the dentine and pulp. Other forms of erosion include tooth abrasion which occurs from improper uses of toothbrushes, brushing too hard, improper flossing or biting on hard foods. And it also includes conditions where natural tooth to tooth friction happens, as in the case of involuntary grinding known as bruxism.

Contraindications

1. Where anaesthesia is contraindicated
2. Where filling can solve the problem
3. Insufficient tooth material
4. Chances of nerve damage
5. Bite misalignment
6. Allergy

As with any medical procedure, it is possible that complications can arise. Among the risk factors and contraindications of dental crown procedures, we can list the following:

1. Contraindication of anaesthesia: Illnesses where the use of anaesthesia is contraindicated. These may include severe heart disease, recent strokes and allergic reactions to anaesthesia.

2. The use of crowns is not indicated in cases where the problem can be solved with a filling.

3. Insufficient tooth material: There is a risk that during the preparation phase, the tooth’s surface can become too thin or be perforated by an instrument.

4. Nerve damage: During the preparation procedure, nerve damage can occur, if this should happen, it will be necessary to perform a root canal.

5. Bite misalignment, although in most cases dental crowns can correct TMJ (temporomandibular joint), if the crown is incorrectly placed, it can exacerbate the problem in some patients. Once the dental crown is in place, your dentist should check the fit taking into account the surrounding teeth as well as the whole bite.

6. Allergic reactions to one or more of the materials. Dental crowns can be made from a variety of materials, choosing the right material will minimize the chances of an allergic reaction.

7. Infections, if the dental crown is not properly sealed or if the damaged tissue was not properly removed, the area might become infected.

 

 

Crown and Bridge

Introduction

A crown is provided to protect the weakened natural tooth, regain its shape, maintain or enhance the esthetics and regain the functional ability of a person. A bridge is a prosthesis that is constructed to replace the one or more missing teeth and is supported by the neighbouring teeth.

A posterior tooth prepared for full crown (pink area)
B-Buccal aspect, L-Lingual aspect

They can be constructed in variety of the materials as follows:

1. All Metal
2. Porcelain fused to metal
3. All ceramic material
4. Pressed ceramic
5. All acrylic

There are various types of crown based on the surfaces they cover.

1. Full coverage crown
2. 3/4 crown
3. 4/5 crown
4. Inlay
5. Onlay

All metal includes precious metals like gold alloys, semi-precious that contains lesser amount of gold and non-precious alloys that are basically chrome- cobalt or nickel- chrome alloys.

Porcelain fused to metal crowns and bridges are made in any one of the above mentioned alloys. This metal crown, in the later phase of construction, is sintered with ceramic powders and chemo-mechanically fuses with metals in ceramic furnace.

“All ceramic” crown is made in Ceramic only. Aesthetically they are the best. Their con is that they are not as strong as metal ceramic or pressed ceramic.

A variety of factors have to be considered for the construction of a bridge.

1. Span of the edentulous area
2. Type of the teeth being replaced
3. Quality of supporting teeth
4. Conditions of the teeth in the opposing arch
5. Age of the patient
6. Patients’ ability to bear the treatment cost

Span of the edentulous area means how many teeth have to be replaced by bridge. The more number of teeth to be replaced, the longer will be the bridge; that in turn, will cause more stress in the bridge itself as well as onto the supporting teeth known as abutments. More stressed bridge will get more fractured ceramic from the metal part.

Type of the teeth decides as to how much masticatory load will have to be borne by the abutments. In case of the lateral incisor pontic, supported by one central incision and one canine, the masticatory load over abutments will be minimum. As we move from the Canines through Premolars to Molars, the quantity of masticatory load increases. Accordingly, we need to increase the number of abutments.

Quality of supporting teeth means how healthy the attachment apparatus of the supporting teeth is present. The healthier the apparatus, the better will be the masticatory load bearing ability of the abutments. It will result in a relatively longer life span of the bridge with minimum number of abutments. If the available healthy root surface area of the abutments will be less than the root surface area of the tooth or teeth being replaced, then more number of teeth should be used as abutment to prevent the overloading of any particular abutment tooth and ultimately bridge failure.

Conditions of the teeth present in the opposite dental arch includes the considerations of occlusal surface of the tooth and whether it is extruded. Is it causing mandible deviation during chewing?

Age wise a very young patient cannot be given crown and bridge as their pulp chambers are usually large and the trauma caused by heat during crown preparation or acids of luring agents may render the pulp tissue dead. This may lead to pulpal or periapical pathology ultimately leading to the failure of the bridge.

Preparation features for anterior crowns [1]

Treatment cost of the PFM bridges are very high. Therefore, the patient must understand the importance of the maintenance of the oral hygiene for the longer life of the prosthesis. The patient should be able to bear the cost of this treatment, otherwise a less expensive treatment needing easy maintenance should be chosen.

Preparation features of the posterior crowns [1]

Further Reading: Read BDJ article by clicking at the link

1. Crowns and other extra-coronal restorations: Preparations for full veneer crowns

Code of conduct for Australian Dentists

  

The shared Code of conduct

The shared Code of conduct (the code) applies to registered health practitioners in 12 professions including dentistry. The code sets out National Boards’ expectations of ethical and professional conduct for the health practitioners they regulate. It is governed by AHPRA.
The code outlines 11 principles which include information about how to apply the code in practice. Underpinning the code is the expectation that practitioners will use their professional judgement to achieve the best possible outcomes for their patients.

Put patients first – Safe, effective and collaborative practice

Principle 1. Practitioners should practise safely, effectively and in partnership with patients and colleagues, using patient-centred approaches, and informed by the best available evidence to achieve the best possible patient outcomes.

Aboriginal and Torres Strait Islander health and cultural safety

Principle 2. Practitioners should consider the specific needs of Aboriginal and Torres Strait Islander Peoples and their health and cultural safety, including the need to foster open, honest and culturally safe professional relationships.

Respectful and culturally safe practice for all

Principle 3. Respectful, culturally safe practice requires practitioners to have knowledge of how their own culture, values, attitudes, assumptions and beliefs influence their interactions with people and families, the community and colleagues. Practitioners should communicate with all patients in a respectful way and meet their privacy and confidentiality obligations including when communicating online.

Working with patients

Principle 4. Basing relationships on respect, trust and effective communication enables practitioners to work in partnership with patients. Practitioners should maintain effective and professional relationships with their patients and provide explanations that enable patients to understand and participate in their care.

Working with other practitioners

Principle 5. Good relationships with colleagues and other practitioners strengthen the practitioner-patient relationship, collaboration and enhance patient care. Good relationships require health care to be free of discrimination, bullying and harassment.

Working within the healthcare system

Principle 6. Practitioners have a responsibility to contribute to the effectiveness and efficiency of the healthcare system and use resources wisely.

Minimising risk to patients

Principle 7. Good practice involves putting patient safety, which includes cultural safety, first. Practitioners should minimise risk by maintaining their professional capability through ongoing professional development and self-reflection and understanding and applying the principles of clinical governance, risk minimisation and management in practice.

Professional behaviour

Principle 8. Practitioners must display a standard of professional behaviour that warrants the trust and respect of the community. This includes practising ethically and honestly.

Maintaining practitioner health and wellbeing

Principle 9. For practitioner it is paramount to take care of their health and well being. among other factors, this includes the adoption of appropriate work life balance.

Teaching, supervising and assessing

Principle 10. In order to develop the workforce for future healthcare needs, the practitioner should support and strive for important role of teaching, supervising and mentoring practitioners and students.

Ethical research

Principle 11. Practitioners should recognise the vital role of ethical and evidence-based research to inform quality healthcare and policy development, conduct research ethically and support the decision-making of research participants. 

Fluoride Modalities in Caries Prevention

Use of fluoride for caries prevention 

Fluoride has been widely used for caries prevention for several decades, and it is considered to be one of the most effective measures in reducing the incidence of dental caries. There are different ways to apply fluoride for caries prevention, including:

1. Topical fluoride: This involves applying fluoride directly to the teeth in the form of a gel, foam, varnish, or mouth rinse. Topical fluoride works by strengthening the tooth enamel and making it more resistant to acid attacks. 

1. Systemic fluoride: This involves ingesting fluoride in the form of fluoridated water, dietary supplements, or fluoride-containing toothpaste. Systemic fluoride works by strengthening the teeth from the inside out as the fluoride is incorporated into the developing tooth structure. 

Fluoride helps to prevent caries by: 

1. Reducing demineralization: Acid-producing bacteria in dental plaque can cause the enamel to lose minerals, a process known as demineralization. Fluoride helps to make the enamel more resistant to demineralization by creating a stronger, more acid-resistant mineral structure.
2. Enhancing remineralization: Fluoride can also enhance the remineralization process, where lost minerals are replaced in the enamel, resulting in stronger and healthier teeth.

Overall, the use of fluoride for caries prevention has been shown to be safe and effective, with numerous studies demonstrating its benefits in reducing the incidence of dental caries in both children and adults. 

 

Reduction of caries incidences due to fluoride use in Australia in children below 12 years of age.

The use of fluoride for caries prevention has been widely implemented in Australia since the 1960s. The Australian government has mandated the fluoridation of community water supplies since the 1970s, and fluoride toothpaste is widely available and recommended by dental professionals for daily use. 

The National Child Oral Health Study, conducted in 2012-2014, found that the prevalence of caries in Australian children aged 5-6 years was 32.7%, while for children aged 9-10 years, it was 43.1%. However, it should be noted that these rates vary across different regions of Australia and are influenced by factors such as socio-economic status, oral health behaviors, and access to dental care. 

Overall, studies have shown that the use of fluoride has led to a significant reduction in caries incidence in Australian children. According to the Australian Dental Association, the prevalence of caries in Australian children has declined by around 50% since the 1970s, with fluoridation of community water supplies being one of the most significant contributors to this reduction. 

Moreover, a systematic review of studies on the effectiveness of water fluoridation in Australia and New Zealand found that water fluoridation led to a 26% reduction in caries in deciduous teeth and a 29% reduction in permanent teeth in children aged 5-12 years. 

In conclusion, the use of fluoride in Australia has contributed significantly to the reduction of caries incidence in children below 12 years of age. Fluoridation of community water supplies, fluoride toothpaste, and other forms of fluoride applications have all played a crucial role in improving the oral health of Australian children. 

Write a detailed note on different preparations of fluoride along with compositions for application on teeth for caries prevention. 

Fluoride is a mineral that is essential for healthy tooth development and has been shown to be effective in preventing dental caries. There are several different preparations of fluoride available for use in dental care, including:

 

5. Fluoride toothpaste: Fluoride toothpaste is the most commonly used fluoride preparation for caries prevention. It typically contains 1000 to 1500 parts per million (ppm) of fluoride and is recommended for twice-daily use. The fluoride in toothpaste works by remineralizing the tooth enamel and making it more resistant to acid attacks.

6.  

6. Fluoride mouthwash: Fluoride mouthwash is another form of topical fluoride application that is used to prevent caries. It typically contains 0.05% sodium fluoride and is used once or twice daily after brushing. The fluoride in mouthwash helps to strengthen the tooth enamel and prevent demineralization. 

7. 
   

7. Fluoride varnish: Fluoride varnish is a topical fluoride application that is applied directly to the teeth by a dental professional. It typically contains 22,600 ppm of fluoride and is recommended for use every 3 to 6 months. The fluoride in varnish works by strengthening the tooth enamel and making it more resistant to acid attacks. 

8. 
   

8. Fluoride gel: Fluoride gel is a topical fluoride application that is applied directly to the teeth by a dental professional. It typically contains 1.23% fluoride and is recommended for use every 3 to 6 months. The fluoride in gel works by remineralizing the tooth enamel and making it more resistant to acid attacks.

9.  

9. Fluoride foam: Fluoride foam is a topical fluoride application that is applied directly to the teeth by a dental professional. It typically contains 1.23% fluoride and is recommended for use every 3 to 6 months. The fluoride in foam works by remineralizing the tooth enamel and making it more resistant to acid attacks.

10.  

10. Fluoride tablets: Fluoride tablets are a form of systemic fluoride application that are ingested by individuals. They typically contain 0.25 to 1.0 mg of fluoride and are recommended for use in children who do not have access to fluoridated water. The fluoride in tablets works by strengthening the teeth from the inside out and making them more resistant to acid attacks.

11.  

Overall, fluoride is an essential mineral for healthy teeth, and its use in dental care has been shown to be effective in preventing caries. Different forms of fluoride preparations are available for use, and the choice of preparation depends on individual needs and preferences. Consultation with a dental professional can help determine the most appropriate fluoride preparation for an individual's oral health needs. 

SBQ

Scenario: Sarah is a 2-year-old child living in Australia where the potable water contains 2 ppm fluoride. Her parents are concerned about her dental health and want to prevent dental caries. 

Question: What is the most effective way to prevent dental caries in Sarah? 

A) Giving her fluoride supplements

B) Using fluoride toothpaste twice a day

C) Using a fluoride mouthwash once a day

D) Taking her to the dentist every 6 months for fluoride varnish application

E) All of the above 

Correct Answer: B) Using fluoride toothpaste twice a day. 

Explanation:

For a 2-year-old child living in an area where the potable water contains 2 ppm fluoride, using fluoride toothpaste twice a day is the most effective way to prevent dental caries. Fluoride supplements are not recommended for children under the age of 3, and a fluoride mouthwash may be difficult for a young child to use properly. While taking Sarah to the dentist every 6 months for fluoride varnish application can be helpful, it is not the most effective means of preventing caries at home. Therefore, option B is the most probable correct answer for this scenario.

Do more SBQ practice in Iridium course.

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