62 - bridge restoration classification. Types of connection between retainer and pontic -

sections

• what is bridge?

• classification based on mode of retention

• Describe simple FPDs

• classifications based on site

• types of connectors between retainer and pontics

• what is bridge?

• fixed partial denture (FPD). They are used to replace missing teeth when there are sufficient number of adjacent teeth sitting next to the missing ones.

• Bridge restoration are used when the need for replacing missing teeth is obvious to the patient. This happens when the edentulous space is in both anterior and posterior regions.

• classification based on mode of retention

According to the mode of retention:

1. Simple FPDs

2. Compound FPDs

Fixed Fixed

• rigid connectors are present at both ends of pontics

• maximum retention and strength

• long span bridges

• All retainers are major retainers and require extensive preparation reduction of the abutment

• one path of insertion, with preparation of both abutments being parallel

• entire occlusal surface of both abutements should be covered with the retainer to distribute occlusal forces evenly

• All retainers should have approx same degree of retention to minimise risk of dislodging a weak retainer

• More tooth structure reduction leads to more destruction and trauma to pulp

• Abutement teeth are splinted together which is beneficial for mobile teeth

• This type of bridge is cemented as one piece

Fixed free bridges

• has rigid connector (major) at distal end of pontic and a mobile connector (minor) mesially

• more conservative to tooth structure compared to fixed-fixed because the minor retainer requires less reduction

• allows for minor tooth movement, both laterally and vertically

• limited to one missing tooth and has span length (distance between abutment teeth) limitation

• parts of bridge can be cemented separately, so lab construction is complex and difficult

• preparation of abutement does not need to be parallel

• Fixed-free is indicated for use in cases of divergent abutment teeth (unparallel), when pier abutment is present (complex bridge) and for aesthetic considerations (such as a class III inlay on distal of canine)

Simple cantilever

• this design provides support for the pontic at only one end

• pontic can be attached to one or two retainers

• abutment tooth is either mesial or distal to the span

• most conservative design when only one abutment tooth is available

• It’s a successful design for replacing a lateral incisor using the canine as an abutment, especially when the occlusion is favourable

• The design can also be used to replace upper or lower first premolars and second molars

Spring cantilever

• abutement tooth is usually posterior and should be a tooth that needs restoration

• pontic is connected to retainer by long flexible metal bar

• design is contraindicated is cases of a V-shaped or narrow palate and is not recommended for the lower arch

• Indicated for replacing a missing upper incisor when adjacent teeth are healthy, in cases of midline diastema (gap between the two upper front teeth (maxillary central incisors)) or when posterior teeth need crowns

• Not advised for the lower arch due to the stability of the sub-mucosal tissue and potential for plaque and calculus deposition

• classifications based on site

• Anterior:

  • uni-lateral

  • bi-lateral

• Posterior

• Complex

• types of connectors between retainer and pontics

• Rigid connector — a cast soldered or fused union between the pontic and retainer.

• Non-rigid connector — any connector that permits limited movement between otherwise, independent members of the FPD. Basically, non-rigid fixed partial dentures transfers shear stress to supporting bone rather than concentrating it in the connectors, while permitting the abutments to move.