NEET MDS Lessons
Pedodontics
Paralleling Technique in Dental Radiography
Overview of the Paralleling Technique
The paralleling technique is a method used in dental radiography to obtain accurate and high-quality images of teeth. This technique ensures that the film and the long axis of the tooth are parallel, which is essential for minimizing distortion and maximizing image clarity.
Principles of the Paralleling Technique
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Parallel Alignment:
- The fundamental principle of the paralleling technique is to maintain parallelism between the film (or sensor) and the long axis of the tooth in all dimensions. This alignment is crucial for accurate imaging.
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Film Placement:
- To achieve parallelism, the film packet is positioned farther away from the object, particularly in the maxillary region. This distance can lead to image magnification, which is an undesirable effect.
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Use of a Longer Cone:
- To counteract the magnification caused by increased film distance, a
longer cone (position-indicating device or PID) is employed. The longer
cone helps:
- Reduce Magnification: By increasing the distance from the source of radiation to the film, the image size is minimized.
- Enhance Image Sharpness: A longer cone decreases the penumbra (the blurred edge of the image), resulting in sharper images.
- To counteract the magnification caused by increased film distance, a
longer cone (position-indicating device or PID) is employed. The longer
cone helps:
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True Parallelism:
- Striving for true parallelism enhances image accuracy, allowing for better diagnostic quality.
Film Holder and Beam-Aligning Devices
- Film Holder:
- A film holder is necessary when using the paralleling technique, as it helps maintain the correct position of the film relative to the tooth.
- Some film holders are equipped with beam-aligning devices that assist in ensuring parallelism and reducing partial exposure of the film, thereby eliminating unwanted cone cuts.
Considerations for Pediatric Patients
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Size Adjustment:
- For smaller children, the film holder may need to be reduced in size to accommodate both the film and the child’s mouth comfortably.
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Operator Error Reduction:
- Proper use of film holders and beam-aligning devices can help minimize operator error and reduce the patient's exposure to radiation.
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Challenges with Film Placement:
- Due to the shallowness of a child's palate and floor of the mouth, film placement can be somewhat compromised. However, with careful technique, satisfactory films can still be obtained.
Pulpectomy
Primary tooth endodontics, commonly referred to as pulpectomy, is a dental procedure aimed at treating the pulp of primary (deciduous) teeth that have become necrotic or infected. The primary goal of this treatment is to maintain the integrity of the primary tooth, thereby preserving space for the permanent dentition and preventing complications associated with tooth loss.
Indications for Primary Tooth Endodontics
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Space Maintenance:
The foremost indication for performing a pulpectomy on a primary tooth is to maintain space in the dental arch. The natural primary tooth serves as the best space maintainer, preventing adjacent teeth from drifting into the space left by a lost tooth. This is particularly crucial when the second primary molars are lost before the eruption of the first permanent molars, as constructing a space maintainer in such cases can be challenging. -
Restorability:
The tooth must be restorable with a stainless steel crown. If the tooth is structurally sound enough to support a crown after the endodontic treatment, pulpectomy is indicated. -
Absence of Pathological Root Resorption:
There should be no significant pathological root resorption present. The integrity of the roots is essential for the success of the procedure and the longevity of the tooth. -
Healthy Bone Layer:
A layer of healthy bone must exist between the area of pathological bone resorption and the developing permanent tooth bud. Radiographic evaluation should confirm that this healthy bone layer is present, allowing for normal bone healing post-treatment. -
Presence of Suppuration:
The presence of pus or infection indicates that the pulp is necrotic, necessitating endodontic intervention. -
Pathological Periapical Radiolucency:
Radiographic evidence of periapical radiolucency suggests that there is an infection at the root apex, which can be treated effectively with pulpectomy.
Contraindications for Primary Tooth Endodontics
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Floor of the Pulp Opening into the Bifurcation:
If the floor of the pulp chamber opens into the bifurcation of the roots, it complicates the procedure and may lead to treatment failure. -
Extensive Internal Resorption:
Radiographic evidence of significant internal resorption indicates that the tooth structure has been compromised to the extent that it cannot support a stainless steel crown, making pulpectomy inappropriate. -
Severe Root Resorption:
If more than two-thirds of the roots have been resorbed, the tooth may not be viable for endodontic treatment. -
Inaccessible Canals:
Teeth that lack accessible canals, such as first primary molars, may not be suitable for pulpectomy due to the inability to adequately clean and fill the canals.
The Pulpectomy Procedure
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Accessing the Pulp Chamber:
The procedure begins with the use of a high-speed bur to create an access opening into the pulp chamber of the affected tooth. -
Canal Preparation:
Hedstrom files are employed to clean and shape the root canals. This step is crucial for removing necrotic tissue and debris from the canals. -
Irrigation:
The canals are irrigated with sodium hypochlorite (hypochlorite solution) to wash out any remaining tissue and loose dentin, ensuring a clean environment for filling. -
Filling the Canals:
After thorough cleaning and shaping, the canals and pulp chamber are filled with zinc oxide eugenol, which serves as a biocompatible filling material. -
Post-Operative Evaluation:
A post-operative radiograph is taken to evaluate the condensation of the filling material and ensure that the procedure was successful. -
Restoration:
Finally, the tooth is restored with a stainless steel crown to provide protection and restore function.
Cherubism
Cherubism is a rare genetic disorder characterized by bilateral or asymmetric enlargement of the jaws, primarily affecting children. It is classified as a benign fibro-osseous condition and is often associated with distinctive radiographic and histological features.
Clinical Presentation
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Jaw Enlargement:
- Patients may present with symmetric or asymmetric enlargement of the mandible and/or maxilla, often noticeable at an early age.
- The enlargement can lead to facial deformities and may affect the child's appearance and dental alignment.
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Tooth Eruption and Loss:
- Teeth in the affected areas may exfoliate prematurely due to loss of support, root resorption, or interference with root development in permanent teeth.
- Spontaneous loss of teeth can occur, or children may extract teeth themselves from the soft tissue.
Radiographic Features
- Bone Destruction:
- Radiographs typically reveal numerous sharp, well-defined multilocular areas of bone destruction.
- There is often thinning of the cortical plate surrounding the affected areas.
- Cystic Involvement:
- The radiographic appearance is often described as "soap bubble" or "honeycomb" due to the multilocular nature of the lesions.
Case Report
- Example: McDonald and Shafer reported a case involving
a 5-year-old girl with symmetric enlargement of both the mandible and
maxilla.
- Radiographic Findings: Multilocular cystic involvement was observed in both the mandible and maxilla.
- Skeletal Survey: A complete skeletal survey did not reveal similar lesions in other bones, indicating the localized nature of cherubism.
Histological Features
- Microscopic Examination:
- A biopsy of the affected bone typically shows a large number of multinucleated giant cells scattered throughout a cellular stroma.
- The giant cells are large, irregularly shaped, and contain 30-40 nuclei, which is characteristic of cherubism.
Pathophysiology
- Genetic Basis: Cherubism is believed to have a genetic component, often inherited in an autosomal dominant pattern. Mutations in the SH3BP2 gene have been implicated in the condition.
- Bone Remodeling: The presence of giant cells suggests an active process of bone remodeling and resorption, contributing to the characteristic bone changes seen in cherubism.
Management
- Monitoring: Regular follow-up and monitoring of the condition are essential, especially during periods of growth.
- Surgical Intervention: In cases where the enlargement causes significant functional or aesthetic concerns, surgical intervention may be considered to remove the affected bone and restore normal contour.
- Dental Care: Management of dental issues, including premature tooth loss and alignment problems, is crucial for maintaining oral health.
Autism Spectrum Disorder
- Onset Timeline: Symptoms typically manifest before 2-3 years of age
- Early Recognition: Critical for intervention and improved outcomes
- Dental Implications: May affect cooperation during dental procedures, sensory sensitivities
Enuresis (Bedwetting)
- Primary Treatment: Bell alarm system (conditioning therapy)
- Mechanism: Moisture sensor triggers alarm when urination begins, conditioning child to wake
- Success Rate: Highly effective behavioral intervention with long-term results
- Plasma peak of fluoride: 180 min
- Fluoride in breast milk: 5 – 10 mg/L
- Earth’s crust fluoride: ~300 ppm
- Dry tea leaf fluoride: 100 – 400 ppm
- Renal clearance: 30 – 50 mL/min
- Plasma fluoride level: 19 – 38 ng/mL
- Plaque fluoride concentration: 15 – 64 ppm
- Sweat fluoride concentration: 0.067 – 0.05 ppm
- Reliable fluoride analysis method: Microdiffusion (Taves, 1983)
- Fluoride in pea-sized toothpaste: 250 mg
- Non-caloric sweeteners: Saccharin, Aspartame
- Most common transposition: Maxillary canine & 1st premolar
- Mandibular eruption sequence: 6, 1, 2, 3, 4, 5, 7
- Maxillary eruption sequence: 6, 1, 2, 4, 5, 3, 7
- Flush terminal plane outcome: First molars erupt end-to-end
- Critical age for occlusion supervision: 7 – 10 years
- Most Successful Injection Site: First primary molar region
- Anatomical Rationale:
- Mandibular foramen positioned lower in children compared to adults
- Location corresponds to occlusal plane of first primary molar
- Provides optimal access to inferior alveolar nerve
- Clinical Technique:
- Injection height: Level with occlusal surface of primary first molar
- Approach: From contralateral premolar/molar region
- Depth: Approximately 15-20mm in young children
- Success Factors:
- Accounts for anatomical differences in pediatric patients
- Reduces risk of trismus and soft tissue trauma
- Higher success rate compared to traditional adult technique