Polycarbonate Crowns in Pedodontics

Polycarbonate crowns are commonly used in pediatric dentistry, particularly for managing anterior teeth affected by nursing bottle caries. These crowns serve as temporary fixed prostheses for primary teeth, providing a functional and aesthetic solution until the natural teeth exfoliate. This lecture will discuss the indications, contraindications, and advantages of polycarbonate crowns in pedodontic practice.

Nursing Bottle Caries

• Definition: Nursing bottle caries, also known as early childhood caries, is a condition characterized by the rapid demineralization of the anterior teeth, primarily affecting the labial surfaces.
• Progression: The lesions begin on the labial face of the anterior teeth and can lead to extensive demineralization, affecting the entire surface of the teeth.
• Management Goal: The primary objective is to stabilize the lesions without attempting a complete reconstruction of the coronal anatomy.

Treatment Approach

1. Preparation of the Lesion:

   • The first step involves creating a clean periphery around the carious lesion using a small round bur.
   • Care should be taken to leave the central portion of the affected dentin intact to avoid pulp exposure.
   • This preparation allows for effective ion exchange with glass ionomer materials, facilitating a good seal.

2. Use of Polycarbonate Crowns:

   • Polycarbonate crowns are indicated as temporary crowns for deciduous anterior teeth that will eventually exfoliate.
   • They provide a protective covering for the tooth while maintaining aesthetics and function.

Contraindications for Polycarbonate Crowns

Polycarbonate crowns may not be suitable in certain situations, including:

• Severe Bruxism: Excessive grinding can lead to premature failure of the crown.
• Deep Bite: A deep bite may cause undue stress on the crown, leading to potential fracture or dislodgment.
• Excessive Abrasion: High levels of wear can compromise the integrity of the crown.

Advantages of Polycarbonate Crowns

Polycarbonate crowns offer several benefits in pediatric dentistry:

• Time-Saving: The application of polycarbonate crowns is relatively quick, making them efficient for both the clinician and the patient.
• Ease of Trimming: These crowns can be easily trimmed to achieve the desired fit and contour.
• Adjustability: They can be adjusted with pliers, allowing for modifications to ensure proper seating and comfort for the patient.

Erikson's Eight Stages of Psychosocial Development

1. Basic Trust versus Basic Mistrust (Hope):

   • Age: Infants (0-1 year)
   • Description: In this stage, infants learn to trust their caregivers and the world around them. Consistent and reliable care leads to a sense of security.
   • Positive Outcome: If caregivers provide reliable care and affection, the infant develops a sense of trust, leading to feelings of safety and hope.
   • Negative Outcome: Inconsistent or neglectful care can result in mistrust, leading to anxiety and insecurity.

2. Autonomy versus Shame and Doubt (Will):

   • Age: Toddlers (1-2 years)
   • Description: As toddlers begin to explore their environment and assert their independence, they face the challenge of developing autonomy.
   • Positive Outcome: Encouragement and support from caregivers foster a sense of autonomy and confidence in their abilities.
   • Negative Outcome: Overly critical or controlling caregivers can lead to feelings of shame and doubt about their abilities.

3. Initiative versus Guilt (Purpose):

   • Age: Early Childhood (2-6 years)
   • Description: Children begin to initiate activities, assert control over their environment, and develop a sense of purpose.
   • Positive Outcome: When children are encouraged to take initiative, they develop a sense of purpose and leadership.
   • Negative Outcome: If their initiatives are met with criticism or discouragement, they may develop feelings of guilt and inhibition.

4. Industry versus Inferiority (Competence):

   • Age: Elementary and Middle School (6-12 years)
   • Description: Children learn to work with others and develop skills and competencies. They begin to compare themselves to peers.
   • Positive Outcome: Success in school and social interactions fosters a sense of competence and achievement.
   • Negative Outcome: Failure to succeed or negative comparisons can lead to feelings of inferiority and a lack of self-worth.

5. Identity versus Role Confusion (Fidelity):

   • Age: Adolescence (12-18 years)
   • Description: Adolescents explore their personal identity, values, and beliefs, seeking to establish a sense of self.
   • Positive Outcome: Successful exploration leads to a strong sense of identity and fidelity to one's beliefs and values.
   • Negative Outcome: Failure to establish a clear identity can result in role confusion and uncertainty about one's place in the world.

6. Intimacy versus Isolation (Love):

   • Age: Young Adulthood (19-40 years)
   • Description: Young adults seek to form intimate relationships and connections with others.
   • Positive Outcome: Successful relationships lead to deep connections and a sense of love and belonging.
   • Negative Outcome: Fear of intimacy or failure to form meaningful relationships can result in feelings of isolation and loneliness.

7. Generativity versus Stagnation (Care):

   • Age: Middle Adulthood (40-65 years)
   • Description: Adults strive to contribute to society and support the next generation, often through parenting, work, or community involvement.
   • Positive Outcome: A sense of generativity leads to feelings of productivity and fulfillment.
   • Negative Outcome: Failure to contribute can result in stagnation and a sense of unfulfillment.

8. Integrity versus Despair (Wisdom):

   • Age: Late Adulthood (65 years to death)
   • Description: Older adults reflect on their lives and evaluate their experiences.
   • Positive Outcome: A sense of integrity arises from a life well-lived, leading to feelings of wisdom and acceptance.
   • Negative Outcome: Regret over missed opportunities or unresolved conflicts can lead to despair and dissatisfaction with life.

Composition of Stainless Steel Crowns

Stainless steel crowns (SSCs) are primarily made from a specific type of stainless steel alloy, which provides the necessary strength, durability, and resistance to corrosion. Here’s a breakdown of the composition of the commonly used stainless steel crowns:

1. Stainless Steel (18-8) Austenitic Alloy:

• Common Brands: Rocky Mountain, Unitek
• Composition:
  • Iron: 67%
  • Chromium: 17%
  • Nickel: 12%
  • Carbon: 0.08 - 0.15%

This composition provides the crowns with excellent mechanical properties and resistance to corrosion, making them suitable for use in pediatric dentistry.

2. Nickel-Based Crowns:

• Examples: Inconel 600, 3M crowns
• Composition:
  • Iron: 10%
  • Chromium: 16%
  • Nickel: 72%
  • Others: 2%

Nickel-based crowns are also used in some cases, offering different properties and benefits, particularly in terms of strength and biocompatibility.

Growth Theories

Understanding the growth of craniofacial structures is crucial in pedodontics, as it directly influences dental development, occlusion, and treatment planning. Various growth theories have been proposed to explain the mechanisms behind craniofacial growth, each with its own assumptions and clinical implications.

Growth Theories Overview

1. Genetic Theory (Brodle, 1941)

• Assumption: Genes control all aspects of growth.
• Application: While genetic factors play a role, external factors significantly modify growth, reducing the sole impact of genetics. Inheritance is polygenic, influencing predispositions such as Class III malocclusion.

2. Scott’s Hypothesis (1953)

• Assumption: Cartilage has innate growth potential, which is later replaced by bone.
• Application:
  • Mandibular growth is likened to long bone growth, with the condyles acting as diaphysis.
  • Recent studies suggest that condylar growth is primarily reactive rather than innate.
  • Maxillary growth is attributed to the translation of the nasomaxillary complex.

3. Sutural Dominance Theory (Sicher, 1955)

• Assumption: Sutural connective tissue proliferation leads to appositional growth.
• Application:
  • Maxillary growth is explained by pressure from sutural growth.
  • Limitations include inability to explain:
    • Lack of growth in suture transplantation.
    • Growth in cleft palate cases.
    • Sutural responses to external influences.

4. Moss’s Functional Theory (1962)

• Assumption: Functional matrices (capsular and periosteal) control craniofacial growth, with bone responding passively.
• Application:
  • Examples include excessive cranial vault growth in hydrocephalus cases, illustrating the influence of functional matrices on bone growth.

5. Van Limborgh’s Theory (1970)

• Assumption: Skeletal morphogenesis is influenced by:
  1. Intrinsic genetic factors
  2. Local epigenetic factors
  3. General epigenetic factors
  4. Local environmental factors
  5. General environmental factors
• Application:
  • Highlights the interaction between genetic and environmental factors, emphasizing that muscle and soft tissue growth also has a genetic component.
  • Predicting facial dimensions based on parental studies is limited due to the polygenic and multifactorial nature of growth.

6. Petrovic’s Hypothesis (1974, Cybernetics)

• Assumption: Primary cartilage growth is influenced by differentiation of chondroblasts, while secondary cartilage has both direct and indirect effects on growth.
• Application:
  • Explains the action of functional appliances on the condyle.
  • The upper arch serves as a mold for the lower arch, facilitating optimal occlusion.

7. Neurotropism (Behrents, 1976)

• Assumption: Nerve impulses, through axoplasmic transport, have direct growth potential and influence soft tissue growth indirectly.
• Application:
  • The effect of neurotropism on growth is reported to be negligible, suggesting limited clinical implications.

Clinical Implications

Understanding these growth theories is essential for pediatric dentists in several ways:

• Diagnosis and Treatment Planning: Knowledge of growth patterns aids in diagnosing malocclusions and planning orthodontic interventions.
• Timing of Interventions: Recognizing the stages of growth can help in timing treatments such as extractions, space maintainers, and orthodontic appliances.
• Predicting Growth Outcomes: Awareness of genetic and environmental influences can assist in predicting treatment outcomes and managing patient expectations.

Distal Shoe Space Maintainer

The distal shoe space maintainer is a fixed appliance used in pediatric dentistry to maintain space in the dental arch following the early loss or removal of a primary molar, particularly the second primary molar, before the eruption of the first permanent molar. This appliance helps to guide the eruption of the permanent molar into the correct position.

Indications

• Early Loss of Second Primary Molar:
  • The primary indication for a distal shoe space maintainer is the early loss or removal of the second primary molar prior to the eruption of the first permanent molar.
  • It is particularly useful in the maxillary arch, where bilateral space loss may necessitate the use of two appliances to maintain proper arch form and space.

Contraindications

1. Inadequate Abutments:

   • The presence of multiple tooth losses may result in inadequate abutments for the appliance, compromising its effectiveness.

2. Poor Patient/Parent Cooperation:

   • Lack of cooperation from the patient or parent can hinder the successful use and maintenance of the appliance.

3. Congenitally Missing First Molar:

   • If the first permanent molar is congenitally missing, the distal shoe may not be effective in maintaining space.

4. Medical Conditions:

   • Certain medical conditions, such as blood dyscrasias, congenital heart disease (CHD), rheumatic fever, diabetes, or generalized debilitation, may contraindicate the use of a distal shoe due to increased risk of complications.

Limitations/Disadvantages

1. Overextension Risks:

   • If the distal shoe is overextended, it can cause injury to the permanent tooth bud of the second premolar, potentially leading to developmental issues.

2. Underextension Risks:

   • If the appliance is underextended, it may allow the molar to tip into the space or over the band, compromising the intended space maintenance.

3. Epithelialization Prevention:

   • The presence of the distal shoe may prevent complete epithelialization of the extraction socket, which can affect healing.

4. Eruption Path Considerations:

   • Ronnermann and Thilander (1979) discussed the path of eruption, noting that drifting of teeth occurs only after eruption through the bone covering. The lower first molar typically erupts occlusally to contact the distal crown surface of the primary molar, using that contact for uprighting. Isolated cases of ectopic eruption should be considered when evaluating the eruption path.

Three Sub-Stages of Adolescence

Adolescence is a critical developmental period characterized by significant physical, emotional, and social changes. It is typically divided into three sub-stages: early adolescence, middle adolescence, and late adolescence. Each sub-stage has distinct characteristics that influence the development of identity, social relationships, and behavior.

Sub-Stages of Adolescence

1. Early Adolescence (Approximately Ages 10-13)

• Characteristics:
  • Casting Off of Childhood Role: This stage marks the transition from childhood to adolescence. Children begin to distance themselves from their childhood roles and start to explore their emerging identities.
  • Physical Changes: Early physical development occurs, including the onset of puberty, which brings about changes in body shape, size, and secondary sexual characteristics.
  • Cognitive Development: Adolescents begin to think more abstractly and critically, moving beyond concrete operational thinking.
  • Emotional Changes: Increased mood swings and emotional volatility are common as adolescents navigate their new feelings and experiences.
  • Social Changes: There is a growing interest in peer relationships, and friendships may begin to take on greater importance - Exploration of Interests: Early adolescents often start to explore new interests and hobbies, which can lead to the formation of new social groups.

2. Middle Adolescence (Approximately Ages 14-17)

• Characteristics:
  • Participation in Teenage Subculture: This stage is characterized by a deeper involvement in peer groups and the teenage subculture, where social acceptance and belonging become paramount.
  • Identity Formation: Adolescents actively explore different aspects of their identity, including personal values, beliefs, and future aspirations.
  • Increased Independence: There is a push for greater autonomy from parents, leading to more decision-making and responsibility.
  • Romantic Relationships: The exploration of romantic relationships becomes more prominent, influencing social dynamics and emotional experiences.
  • Risk-Taking Behavior: Middle adolescents may engage in risk-taking behaviors as they seek to assert their independence and test boundaries.

3. Late Adolescence (Approximately Ages 18-21)

• Characteristics:
  • Emergence of Adult Behavior: Late adolescence is marked by the transition into adulthood, where individuals begin to take on adult roles and responsibilities.
  • Refinement of Identity: Adolescents solidify their sense of self, integrating their experiences and values into a coherent identity.
  • Future Planning: There is a focus on future goals, including education, career choices, and long-term relationships.
  • Social Relationships: Relationships may become more mature and stable, with a shift from peer-focused interactions to deeper connections with family and romantic partners.
  • Cognitive Maturity: Cognitive abilities continue to develop, leading to improved problem-solving skills and critical thinking.