BDS 11079 Overdenture and attahments.pdf

BDS11079 Over-denture and attachment Date : 2023 Advantages of Overdentures 1- Preservation of residual ridge . • Improved occlusal stress distribution. N.B: Mandibular bone is affected four times more than the maxillary bone. 2- Preservation of proprioceptive response: Enhance neuromascular...

BDS11079 Over-denture and attachment Date : 2023 Advantages of Overdentures 1- Preservation of residual ridge . • Improved occlusal stress distribution. N.B: Mandibular bone is affected four times more than the maxillary bone. 2- Preservation of proprioceptive response: Enhance neuromascular control , occlusal awareness and biting force. 3- Stability, Support. • Bone preservation by reducing trauma to soft tissues. 4- Retention. • Through Attachments 5-Patient acceptance and Psychological Benefits 6- Convertibility 7-Conventional dental procedures Disadvantages of Overdentures 1-Caries susceptibility. 2- Bony undercuts: Excessive bony undercut may limit the path of insertion of the overdenture. 3-Periodontal breakdown abutment teeth. of the – Gingivitis – Periodontitis – Hyperplasia 4- Inadequate reduction of the abutment teeth may increased vertical dimension. 5-Expense and Time consuming. 6-Bulkier 7- Removable Prosthesis Indications for Overdentures • Few remaining teeth are present, not suitable for fixed or RPD • Mobile teeth: Reduction of unhealthy remaining periodontal teeth, decrease the C/R ratio, decrease the hypermobility of teeth. • Severe attrition • Congenital defects • Alternative treatment to single dentures Contraindications for Overdentures • If any other prosthetic plan can give superior results • In cases with poor oral hygiene. • Inadequate interarch distance to accept the denture and abutments. • Abutments exhibiting mobility, which exceeds grade II. Classification of Overdentures Classification of tooth supported overdenture According to design and technique of abutment preparation 1- Simple tooth reduction of vital abutment. 2- Tooth reduction and cast coping of vital abutments (Thimble shape) 3- Endodontic therapy and amalgam plug 4- Endodontic therapy with post and coping 5- Endodontic therapy with cast coping and attachments 6- Telescopic Overdenture 1- Simple tooth reduction of vital abutment. • Indications: • Adequate interarch space • Attrition and abrasion 2- Tooth reduction and cast coping of vital abutments A- Thimble-shaped coping Indications: 1. Partial anodontia.. 2. Enough interarch space B- Tooth reduction and cast coping without endodontic treatment( in severe pulp recession) Abutment preparation 3- Endodontic therapy and amalgam plug Indications: 1. Normal interarch space. 2. Normal crown height 3. Good oral hygene. 4- Endodontic therapy with post and cast coping 5- Endodontic therapy with or without cast coping and attachments 6- Telescopic overdenture Criteria for abutment selection • Position of abutments. • Number of abutments. • Periodontal evaluation. • Endodontic evaluation. • Decay or previous restorations. 1. Position & Number of abutments ⚫ At least one tooth per quadrant. ⚫ Retained teeth should preferable not be adjacent ones. ⚫ There should be several millimeters of space between the reduced tooth forms. ⚫ Canines and premolars are the best overdenture abutments to reduce adverse forces at this site. 2. Periodontal and Mobility Status • Minimal mobility • At least 6mm of bone support (at least 1/3 of the root should be supported by bone) • Attached gingiva around the abutments • Good oral hygiene 3. Endodontic Potential and prosthetic status >Single rooted teeth are easer to treat. >Pulpal recession >Condition of RCT already done. >Potential for RCT. 4. Restorative Condition • The condition of the tooth to be used as an overenture abutment should be assesse regarding its restorability Treatment Planning • Patient Selection • • • • Medical History. Oral Hygiene. Compliance. Motivation. • Abutment selection. • • • • • Position. Number of abutments Periodontal evaluation. Endodontic evaluation. Decay or previous restorations. • Inter-arch space. Clinical Procedures 1-Abutment preparation: - Periodontal treatment. - Crown reduction and contouring with or without endodontic treatment depending on the type of overdenture to be fabricated. - Coping fabrication: impression- die preparation - wax pattern - casting cementation Clinical procedures 2-Primary impression: alginate impression in stock tray. 3- Special trays constructed on primary cast. 4- Secondary impression Clinical procedures 5- Jaw Relation Records: Mounting of upper cast on a semi-adjustable articulator by face-bow record of lower cast by centric occluding relation mounting setting up of teeth. 6- Try in • Fitting surface of the trial denture should be relieved over the abutments for proper denture settling • check for stability • check vertical dimension • check occlusion. 7- Denture processing 8- Denture insertion 9- Post-insertion care Clinical procedures Attachments • An attachment is defined as a mechanical device used for retention and stabilization of a prosthesis. •It falls in two categories: 1. PRECISION ATTACHMENTS Ready made attachment their component are machined in a especial alloys under precise tolerance. Less wear, Standard parts, easier to repair. 2- SEMI- PRECISION ATTACHMENTS semi- precision attachment is fabricated by the direct casting of plastic, wax or refractory patterns, subject to variables of fabrication, economy. •Rigid attachments: do not allow for movement of the denture base providing adequate retention. However, may induce more torque on the abutments. •Resilient attachments: allow some controlled vertical and lateral movement. They induce less torque on abutments. However, they are more complex in design and fabrication. Factors affecting Selection of Overdenture Attachments 1- Crown root ratio. 2- Type of coping. Attachment selection it based on: 3- Vertical space available. 4- Number of teeth present. 5- Amount of bone support. 6- Location of abutments. 7-Available inter-arch space 8- Location of the strongest abutments. 9- Whether the overdenture is to be a tooth-supported or tooth-tissue supported. 10- Type of the opposing dentition whether complete denture, overdenture, fixed appliances or natural dentition. 11- The maintenance problems 12- Clinical experience and individual preference 13- Cost Attachments could be classified according to : 1-Location 2-Function 3-Retention 1-Location 1-Intraradicular attachment. 2-Extraradicular attachment. 3-Intracoronal. 4- Extracoonal. 2-Function • it’s important to differentiate between resilient or non resilient type restoration. Abutment/tooth supported restorations are considered non-resilient or solid, while abutment and tissue-supported restorations are considered resilient. 3- Retention of attachments It can be obtained by: • frictional. • mechanical. • frictional and mechanical. • Magnets. Types of attachments 1. Stud attachments 2. Magnets 3. Bar attachments Stud attachment Magnets Keepers Magnets Bar attachments A bar attachment is in the form of a bar contoured to run parallel and overlie the residual ridge connecting the abutments together. The bar provides support and retention for the overdenture and splinting of abutment teeth. (or implants) Oral hygiene maintenance Maintenance •Oral Hygiene • Brushing • Denture kept in tap water when not use. • Frequent recalls For post insertion care and prophylactic care of abutments. (fluoride application) Summary • Definition of overdenture • Indications and contraindications for overdentures • Advantages and disadvantages of tooth supported overdenture • Patient examination • Classification of tooth supported overdentures • Criteria for selecting an overdenture abutment • Procedure for abutment preparation followed to fabricate an overdenture • Attachments used for both tooth and implant supported overdenture