Description of the different types of attachment

Ministry of Higher Education and Scientific Research Faculty of Medicine of BLIDA

Department of Dental Medicine

Academic Year 2023/2024

PLAN

Introduction I-Definition

2. Function of an attachment
3. Classification of attachments
   • Classification of attachments according to their mode of connection
   • Classification of attachments according to their manufacturing method
   • Classification of attachments according to their retention mode
   • Classification of attachments according to their topographical situation IV-Criteria for choosing an attachment

V-General contraindications

VII-Advantages and disadvantages of attachments VIII-Causes of failure

Conclusion Bibliography

Introduction :

Nowadays, patients are increasingly looking for aesthetics; this can be a hindrance, a limit to the classic hook- type attachment system ; hence the interest in precision attachment systems which replace hooks whose vestibular arm is sometimes unsightly.

These retention devices, which appeared at the beginning of the last century, are continually evolving according to

materials used for their manufacture, production techniques, knowledge of the viscoelastic behavior of soft tissues and the periodontal state of the supporting teeth or implants.

1. Definition :

An attachment is a mechanical device made of metal (castable or prefabricated in a laboratory), joining two prosthetic parts together. That is, it is a device connecting a removable prosthesis and a fixed prosthetic part (on natural teeth or artificial roots).

A precision fastening system consists of a male part , also called a patrice ; and a female part , also called a matrix .

• These two elements are the exact negative of one another.
• Their integration within a prosthetic restoration must in no way change the design principles of a PPAC frame.

2. Function of an attachment:

The essential function that an attachment must fulfill is the retention of a prosthesis in a lasting manner over time while allowing satisfactory aesthetics .

For some attachments such as a connection bar or slide, they can have a stabilizing function but to a much lesser extent.

On the other hand, in no case should an attachment have a supporting role . This will be the role of the milled contours, of the extent of the chassis plate.

3. Classification of attachments

The many possible scenarios encountered have led to the design of attachments with different operating modes. The evolution of materials and techniques has also allowed the development of new retention and manufacturing methods. A single classification cannot take all these factors into account.

1. Classification of attachments according to their connection mode (operation): The connection mode corresponds to the connection between the PPAC frame and the other components of the prosthesis, by mechanical elements. Its choice is essential to ensure a harmonious distribution of forces between the dental and mucosal supports.

• Rigid connection: which does not allow any movement of the PPAC, apart from insertion and disinsertion movements (fig. 01). The rigid connection is indicated in maxillary and mandibular embedded edentulism.
• Semi-rigid connection: It allows the prosthesis to move vertically (fig. 02) , thus allowing the masticatory forces to be distributed between the hard and soft tissues. It is indicated for large terminal edentulous areas.

fig. 01: Rigid Connection Attachment fig. 02: Semi-rigid Connection Attachment

2. Classification of attachments according to their manufacturing method

Several manufacturing methods can be used, from the fully prefabricated attachment brazed to the fixed prosthesis or included in a casting, to the attachment manufactured in the laboratory from calcinable preforms and cast at the same time as the fixed prosthesis.

• Fully prefabricated attachments

The prefabricated part is secured to the metal screeds by a connection casting or brazing (fig. 03). This technique is more precise (of the order of 5µm) but more expensive, moreover if there is a failure in the connection casting or in the brazing, everything must be

start again.

• Fully burnable attachments

The calcinable part preforming the attachment is positioned very precisely using a parallelizer on the wax copings of the fixed prostheses (fig. 04) . Then, the laboratory production will be done using the lost wax technique and a direct casting can be carried out. On the other hand, the control of the positioning of the attachment is imperfect due to errors caused by casting and polishing.

fig. 03: Prefabricated alloy attachment

fig. 04: Castable plastic attachment

3. Classification of attachments according to their mode of retention

The essential function of the attachment is the retention of the removable prosthesis, this can be achieved in different ways:

• Friction retention: It is the high precision of adaptation between the male and female part which conditions the friction retention.

exists:

• a metal-metal friction retention which can mainly be activated by moving the male part more or less apart (fig. 05)
• metal-plastic friction retention provided by plastic sheaths of different retentive values. When wear is observed, simply change the plastic sheath of the female part. (fig. 06)
• Retention by passing a line of undercut : These are friction retention supplements. There are two types:

• Locking retention : which is obtained in the maximum insertion position by the engagement of a “clip” in a groove or depression. (fig. 07)
• Retention by exploitation of an undercut area : represented by fins which come to tighten more or less on the lower half of a sphere. This can of course be activated to increase retention. (fig. 08)

4. Classification of attachments according to their topographical location:

This is the most commonly used classification. It consists of classifying precision fastening systems according to the location of the retentive element.

1. Coronary-peripheral attachments

These attachments are arranged either inside a cap or on a proximal face.

• Extra-coronary attachments The attachment is located outside the prosthetic crown in a tangential position. (fig. 09) This creates a significant lever arm which will be compensated by the solidarity of the abutment teeth.

fig. 09

Benefits	Disadvantages
They are aesthetic because the attachment is located under the removable prosthesis; therefore completely invisible. They do not cause interference if the prosthetically usable space “EPU” is favorable. They facilitate hygiene. Dental vitality is more easily preserved because they are more economical in dental tissue (they do not require any special preparation).	They require the abutment teeth to be secured due to the lever arm they create. They require sufficient UPE to accommodate the attachment and the prosthetic tooth. They require perfect hygiene to be sustainable over time.

• Intracoronary attachments:

• These attachments are placed inside a fixed prosthesis element and require special preparation within the abutment tooth to accommodate the attachment (fig. 10), therefore devitalization is almost obligatory.
• Almost all of these systems are rigid. They are generally represented by slides.
• This type of attachment imposes the axis of insertion of the removable prosthesis and remains visible in occlusal view.

(fig. 10)

2. Axial attachments

Axial attachments are based on the principle of a snap button which ensures a connection between a root, natural or artificial, and a PPAC saddle.

They are mainly used on implants and on isolated roots with weak anchorage that cannot support a conventional crown . They can be divided into two groups

• The supra-radiculars: (fig. 11)

• The patrice is at the root level
• The matrix at the PPAC level.

(fig. 11)

• Intra-radicular: inverted supra-radicular attachments (fig. 12)

• The patrice is at the level of the PPAC
• The matrix at the root level.

They require a sufficiently large cameral chamber to accommodate the male part; therefore rather reserved for molars or even premolars.

3. Anchor bars (conjunction or connection bars) (fig. 1 3)

These are bars that hold several teeth or several implants together.

The male part is represented by the bar and the female part is represented by riders or a gutter located in the intrados of the PPAC

(fig. 1 3)

4. Criteria for choosing an attachment:

• Volume : The attachment must provide the necessary space for a sufficiently thick and aesthetic tooth on the PPA
• Possibility of replacement : The attachment must be durable and yet have easily accessible replacement parts.
• Location on the arch : The shape of the edentulous arch, in “U” or “V”, gives prevalence to a type of attachment depending on its mode of action.

5. General contraindications

• Unmotivated patient: Unsatisfied motivation for patient hygiene, or difficulty accessing brushes for the elderly or disabled person.
• Insufficient available space: Insufficient available space and significant undercuts at the level of the vestibular bone tables limit the indications for prefabricated attachments
• Periodontal diseases: A tooth with an uncertain periodontal prognosis may call into question the indication for an attachment
• Financial impossibility.

6. Advantages and disadvantages of attachments

• Benefits :
  • Aesthetic and non-harmful because they are integrated invisibly inside the prosthesis.
  • Ensure good retention of the prosthesis.
• Disadvantages:
  • Very high cost price.
  • The abutment teeth (cast crown or root post cap) must be prepared for this purpose to allow the attachment to be fixed.

7. Causes of failure

• The choice of inappropriate systems, contraindication of attachments or poor biomechanical design of the removable partial prosthesis are major sources of failure.
• Failure to comply with the basic principles of design of the fixed prosthesis-removable prosthesis assembly is punished by root fractures of the supporting teeth, bone resorption, periodontal problems, or fractures of the attachments.

Conclusion

The need to carefully analyze the clinical situation, to evaluate the patient ‘s motivation , cooperation and availability , allows us to guide our therapeutic choice and offer the best solution adapted to their case.

As each case is different, each practitioner’s clinical approach is different, the therapeutic possibilities are multiple. There is no “standard” therapeutic solution; the best solution remains the one that meets the expectations of both the patient and the practitioner and that will remain sustainable.

Bibliography

1. M.Begin –fouilloux Isabelle: Attachments in prosthetics – quintessence international. 2011
2. I.Fouilloux, J.-M. Cheylan: Attachments and removable metallic partial prostheses – EMC – Oral medicine 2019
3. Marcel Begin: Attachments: roles, indications, respective contributions – Paris Odontological Society – SOP
4. Jean Schittly – Estelle Schittly. Removable partial prosthesis, clinical and laboratory: CDP edition

Description of the different types of attachment

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Description of the different types of attachment