Selecion of Major Connectors
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CLASSIC ARTICLE Selection of a major connector for the extension-base removable partial denture Arthur M. LaVere, DDS, a and Arthur J. Krol, DDS b University of the Pacific, School of Dentistry, San Francisco, Calif The selection of a major connector is not a difficult procedure if the dentist considers two important factors. The first is the degree to which the removable partial denture must be supported by structures other than the natural teeth. The second is the degree of rigidity required of the major connector to adequately distrib- ute functional stresses from one side of the arch to the other. PRIMARY FACTORS Support. Support for the maxillary major connector is partly dependent upon the hard palate. The greater the coverage of the hard palate, the greater the support re- ceived from the palate. Thus, the ‘‘snowshoe’’ principle is in effect in that the stress load is distributed over a large area, and the force per unit area is reduced. Unfortunately, support similar to that derived from the palate cannot be obtained from the mandibular re- movable partial denture. Rigidity. Rigidity of a maxillary major connector is enhanced by the joining of the anterior and posterior bars to form a circle. This union makes the major con- nector more than twice as rigid as each bar would be in- dividually. Additional rigidity is obtained by use of the ‘‘L’’ beam effect, i.e., metal lying in two different planes. For the mandibular major connector, encirclement can- not be accomplished. However, acceptable rigidity is obtained by thickening the inferior border of the lingual bar or plate. When considering support and rigidity, Table I will act as a guide for the selection of maxillary and mandib- ular major connectors. SELECTING A MAJOR CONNECTOR A mouth in which the teeth and supporting struc- tures are periodontally diseased might serve as a typical example for the selection of a maxillary major connector. The periodontally diseased mouth requires a rigid major connector that permits optimum palatal support. Therefore, the major connector should be modified so as to distribute the stress over as broad a palatal surface as practicable. Other considerations for selecting a major connector might be whether the removable partial denture is op- posed by an artificial denture, whether the residual ridge tissues are firm or removable, whether the remaining natural occlusion is heavy or weak, whether tori are pre- sent, whether the residual ridges are resorbed, and whether the tissues of the floor of the mouth are at- tached high or low. Preferred maxillary major connectors* Posterior palatal strap. This is a preferred connector because it may be used for most designs, distributes mas- ticatory stress over a wide area, and may be made wide or narrow depending upon the desired stress distribution. A narrow strap (minimum of 8 mm) may be used for all tooth-supported removable partial dentures. The width of the strap should be increased for distal exten- sion bases (Fig. 1). Anteroposterior palatal strap (closed horseshoe). This strap may be used for most maxillary partial denture de- signs and especially when a torus is present. It has the ef- fect of a circle, and the ‘‘L’’ beam effect is present. Anterior and posterior bars (straps) should be at least 8 mm in width (Fig. 2). Complete palatal plate. This connector may be used for bilateral distal extension partial dentures of a long span and may be used in combination with plastic resin (Fig. 3). Table I. Characteristics of major connectors 1 Connector Support Rigidity Posterior palatal strap Good-excellent Good-excellent Anteroposterior palatal strap (closed horseshoe) Good Excellent Complete palatal plate Excellent Excellent Anteroposterior palatal bar Poor Good Posterior palatal bar Poor Poor Anterior palatal strap (horseshoe) Poor Poor Lingual bar None Good Lingual plate None Good-excellent a Associate Professor, Removable Prosthodontics Department b Professor and Chairman, Removable Prosthodontics Department Reprinted with permission from J Prosthet Dent 1973;30:102-5. J Prosthet Dent 2005;94:207-8. *Superior borders are placed a minimum of 6 mm from the gingival margins. SEPTEMBER 2005 THE JOURNAL OF PROSTHETIC DENTISTRY 207
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Transcript of Selecion of Major Connectors
CLASSIC ARTICLE
Selection of amajor connector for the extension-base removable partial denture
Arthur M. LaVere, DDS,a and Arthur J. Krol, DDSb
University of the Pacific, School of Dentistry, San Francisco, Calif
The selection of a major connector is not a difficultprocedure if the dentist considers two important factors.The first is the degree to which the removable partialdenture must be supported by structures other thanthe natural teeth. The second is the degree of rigidityrequired of the major connector to adequately distrib-ute functional stresses from one side of the arch to theother.
PRIMARY FACTORS
Support. Support for the maxillary major connector ispartly dependent upon the hard palate. The greater thecoverage of the hard palate, the greater the support re-ceived from the palate. Thus, the ‘‘snowshoe’’ principleis in effect in that the stress load is distributed over alarge area, and the force per unit area is reduced.Unfortunately, support similar to that derived fromthe palate cannot be obtained from the mandibular re-movable partial denture.
Rigidity. Rigidity of a maxillary major connector isenhanced by the joining of the anterior and posteriorbars to form a circle. This union makes the major con-nector more than twice as rigid as each bar would be in-dividually. Additional rigidity is obtained by use of the‘‘L’’ beam effect, i.e., metal lying in two different planes.For the mandibular major connector, encirclement can-not be accomplished. However, acceptable rigidity isobtained by thickening the inferior border of the lingualbar or plate.
When considering support and rigidity, Table I willact as a guide for the selection of maxillary and mandib-ular major connectors.
SELECTING A MAJOR CONNECTOR
A mouth in which the teeth and supporting struc-tures are periodontally diseased might serve as a typicalexample for the selection of amaxillarymajor connector.The periodontally diseased mouth requires a rigidmajor connector that permits optimum palatal support.Therefore, the major connector should be modified so
aAssociate Professor, Removable Prosthodontics DepartmentbProfessor and Chairman, Removable Prosthodontics DepartmentReprinted with permission from J Prosthet Dent 1973;30:102-5.J Prosthet Dent 2005;94:207-8.
SEPTEMBER 2005
as to distribute the stress over as broad a palatal surfaceas practicable.
Other considerations for selecting a major connectormight be whether the removable partial denture is op-posed by an artificial denture, whether the residual ridgetissues are firm or removable, whether the remainingnatural occlusion is heavy or weak, whether tori are pre-sent, whether the residual ridges are resorbed, andwhether the tissues of the floor of the mouth are at-tached high or low.
Preferred maxillary major connectors*
Posterior palatal strap. This is a preferred connectorbecause itmay be used formost designs, distributesmas-ticatory stress over a wide area, andmay bemade wide ornarrow depending upon the desired stress distribution.A narrow strap (minimum of 8 mm) may be used forall tooth-supported removable partial dentures. Thewidth of the strap should be increased for distal exten-sion bases (Fig. 1).
Anteroposterior palatal strap (closed horseshoe). Thisstrap may be used for most maxillary partial denture de-signs and especially when a torus is present. It has the ef-fect of a circle, and the ‘‘L’’ beam effect is present.Anterior and posterior bars (straps) should be at least8 mm in width (Fig. 2).
Complete palatal plate. This connector may be usedfor bilateral distal extension partial dentures of a longspan and may be used in combination with plastic resin(Fig. 3).
Table I. Characteristics of major connectors1
Connector Support Rigidity
Posterior palatal strap Good-excellent Good-excellent
Anteroposterior palatal
strap (closed horseshoe)
Good Excellent
Complete palatal plate Excellent Excellent
Anteroposterior palatal bar Poor Good
Posterior palatal bar Poor Poor
Anterior palatal strap
(horseshoe)
Poor Poor
Lingual bar None Good
Lingual plate None Good-excellent
*Superior borders are placed a minimum of 6 mm from the gingivalmargins.
THE JOURNAL OF PROSTHETIC DENTISTRY 207
THE JOURNAL OF PROSTHETIC DENTISTRY LAVERE AND KROL
Nonpreferred maxillary major connectors
Anteroposterior palatal bar. This connector may beused where support is not a major consideration; barsare too narrow for adequate support (usually less than8 mm in width).
Posterior palatal bar. This bar may be used for tooth-borne partial dentures only since it lacks rigidity and pro-vides minimum support.
Anterior palatal strap (horseshoe). This connector isvery poor, because it is flexible with buccolingual move-ment occurring at the open ends. However, it may beused where a midline suture or an inoperable palatal to-rus exists.
Mandibular major connectors
Lingual bar. It should be used whenever possible. Itpermits exposure of gingival tissues to normal stimula-
Fig. 3. A complete palatal plate. This major connector maybe used for long bilateral distal extension–base partialdentures, and may be used in combination with resin bases.
Fig. 1. A posterior palatal strap may be used as a majorconnector for long-span unilateral extension-base partialdentures where optimum support and rigidity are desirable.Superior borders are placed a minimum of 6 mm from thegingival margins.
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tion, and the superior margin is located at least 3 mmaway from the gingival margins (Fig. 4).
Linguoplate. The linguoplate must be used when ahigh lingual frenum or the floor of the mouth preventsthe use of a lingual bar. It may be used in combinationwith a labial bar for splinting. Terminal tooth restsshould be used to provide a vertical stop at each end ofthe linguoplate to prevent labial movement of the teeth.
REFERENCE
1. Krol AJ. Removable, partial denture design. Outline syllabus. San Fran-
cisco: University of the Pacific, School of Dentistry; 1972 Nov.
0022-3913/$30.00
Copyright � 2005 by The Editorial Council of The Journal of Prosthetic
Dentistry.
doi:10.1016/j.prosdent.2005.07.005
Fig. 2. An anteroposterior palatal strap (closed horseshoe)provides greater rigidity and support than a single posteriorpalatal strap and is more advantageously used in extension-base partial dentures. This major connector also may be usedvery effectively when anterior teeth are to be replaced.Anterior and posterior bars should be at least 8 mm in width.
Fig. 4. A lingual bar should be used whenever possible. Thesuperior margin should be located at least 3 mm from thegingival margins.
VOLUME 94 NUMBER 3
