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Maxillary Major Connectorslec:3

Dr.Omar S.M.J.Ali
B.D.S , M.Sc. , Ph.D

Basic requirements of maxillary major connectors.

The same of Basic requirements of mandibular major connectors.

Functions of major connector

Unification of the major parts of prosthesis.
Distribution of applied force throughout the arch to selected teeth and tissue.
Minimization of torque to the teeth.
Provides cross arch-stability to help resist displacement by functional stresses.


Failure of major connector to provide rigidity may be manifest by
traumatic damage to periodontal support of abutment teeth,
injury to residual ridges, or
impingement of underlying tissue.

It is the dentist’s responsibility to ensure that the appropriate design and fabrication of the major connector are accomplished.

Special structural requirements of Maxillary Major Connectors :

1- Intimate contact between the tissue side of the connector and the palatal tissues is required to enhance support, retention and stability of the partial denture. For this reason :

a- Relief is avoided under maxillary major connectors.

b- The tissue side of the connector should not be highly polished during the final finishing and polishing procedures.
c- Little relief may be only required in the presence of palatal tori or prominent median palatine raphe.

d- An effective specially prepared seal is required along all borders of maxillary major connectors that are in contact with soft tissues. This seal ensures intimate contact with the palatal tissues and prevents food debris from collecting under the connector. Beading of the maxillary cast is essential to develop this peripheral seal. This beading is prepared on the master cast by scrapping a shallow groove (0.5 mm in width and depth) along the borders of the connector.

2- All borders should be tapered slightly (beveled) towards the tissues so that they are less perceptible by the tongue. Borders should also be smoothly curved and should never be irregular.
3- The thickness of palatal plates should be uniform

TYPES OF MAXILLARY MAJOR CONNECTORS

Single palatal strap
Combination anterior and posterior palatal strap-type connector
Palatal plate-type connector
U-shaped palatal connector
Single palatal bar
Anterior-posterior palatal bars

SINGLE PALATAL STRAP

Single Palatal Strap

Used to connect bilateral tooth-supported prosthesis, even those with short edentulous spaces, particularly when the edentulous areas are located posteriorly.
It can be made rigid without objectionable bulk and interference with the tongue provided the cast framework material is distributed in three planes.







A
B
A, this single palatal strap type major connector is better suited for the restoration of short span tooth supported bilateral edentulous areas.
B, sagittal section. Midportion of major connector demonstrates slight elevation to provide rigidity. Such thickness of major connector does not appreciably alter palatal contours.

For reasons of torque and leverage, it should not be used to connect anterior replacements with distal extension bases.
To be rigid enough to resist torque and provide adequate vertical support and horizontal stabilization, a single palatal strap would have to be objectionably bulky. When placed anteriorly, the bulk would become even more objectionable to the patient interfering with speech.
More frequently used in class III situations.

Disadvantages

• 1- Pt. complaint from
• excessive palatal
• coverage:
• a) Anterior border:
• Posterior to palatal
• ruga or at the posterior
• slope of prominent
• ruga.
• b) Posterior border:.
• Anterior to junction of
• The Hard & The Soft
• palate.
• 2- ↑ Soft tissue coverage
• ↓
• (Papillary hyperplasia)
• a) Denture wearing 24
• hour daily.
• b) Poor oral hygiene.
• c) Inadequate Pt.instru.
• instructions.


COMBINATION ANTERIOR AND POSTERIOR PALATAL STRAP-TYPE CONNECTOR

Combination Anterior and Posterior Palatal Strap-type Connector

Structurally a rigid major connector.
May be used in any maxillary partial denture design.
Posterior palatal strap :
Design- flat and minimum 8 mm wide.
Location- as far posteriorly as possible to avoid interference with tongue but anterior to line of flexure formed by the junction of hard and soft palates.




Anterior component is a flat strap located as far posteriorly as possible to avoid rugae coverage and tongue interference. Anterior border of this strap should be located just posterior to a rugae crest or in the valley between two crests. Posterior strap is thin, a minimum of 8 mm wide, and Is located as far posteriorly as possible, yet entirely on hard palate. It should be located at right angles to midline rather than diagonally.

Contraindication: inoperable maxillary torus that extends posteriorly to soft palate (a broad U-shaped major connector is used).



Strength: lies in the fact that anterior and posterior components are joined together by longitudinal connectors on either side, forming a square or rectangular frame. Each component braces the others against possible torque and flexure.
Use: used most frequently in classes II and IV.
All maxillary major connectors should cross the midline at a right angle rather than on a diagonal.

PALATAL PLATE-TYPE CONNECTOR

Palatal Plate-type Connector

Thin, broad, contoured palatal coverage, covering one half or more of the hard palate.






Palatal major connector covering one half or more of the hard palate. Anterior border follows valleys between rugae and does not extend anterior to indirect retainers on first premolars. Posterior border is located at junction of hard and soft palates but does not extend onto soft palate.

Horseshoe connector

• - Thin band of metal
• running along the lingual
• surfaces of the remaining
• teeth& extended onto the
• palatal tissues for 6-8 mm.
• - Rigidity can increased by
• extending the borders
• slightly onto the horizontal
• surfaces of the hard palate.
• - Should display symmetry
• - Should extend to the
• same height on both sides.
• - All borders should be
• gently curved& smooth.

disadvantages

1- Tendency for the
connector to flex or
deform.
↓
(Stress concentration)
↓
(Abutment damage)
2- To avoid flexing, It
should be thicker than
other major connectors.
(↑ bulk)
↓
(Pt. discomfort&
affecting Phonetics)

Review of Indications of Maxillary Major Connectors:

1- If the periodontal support of the remaining teeth is weak → more of the palate should be covered → A wide palatal strap or a complete palate is indicated.
2- If the remaining teeth have adequate periodontal support and little additional support is needed → a palatal strap or antero-posterior palatal bar may be used.
3- For long-span distal extension bases where rigidity is critical → an antero-posterior palatal strap or complete palate is indicated.

4- When anterior teeth must be replaced → an antero-posterior palatal strap, complete palate, or horseshoe major connector may be used. The final selection must be based on modifying factors such as:
a- number and location of missing posterior teeth. b- periodontal support of remaining teeth.

c- type of opposing occlusion.

5- If a torus is present and is not to be removed → an anteroposterior palatal strap, antero-posterior palatal bar, or horseshoe major connector may be used.

6- A horseshoe connector should be used very sparingly
7- A palatal bar is rarely indicated.



Special structural requirements of Mandibular Major Connectors :
1- Rigidity without produce excessive bulk.
2- Must not impinge upon the movable floor of the mouth, frenum or tori.
3- Require relief between metal and tissues for these factors:
a- For tooth supported edentulous areas: little or no relief is needed → denture doesn't tend to move in function.
b- For distal extension edentulous areas: moderate amount of relief → denture tends to rotate during function.

c- Slope of anterior ridge: if soft tissues slopes towards the tongue → greater amount of relief → prevent laceration on movement.
d- Undercut of anterior ridge: it should be blocked-out.
4- Beading lines not used with the friable mucosa of the mandibular arch.

Review for indications for mandibular major connector:

1- For tooth supported RPD → Lingual bar.
2- Insufficient room between floor of the mouth and gingival margins or large tori → Lingual plate.
3- Low periodontal support for anterior teeth → Lingual plate.

4- Low periodontal support for anterior teeth with wide embrasures → Interrupted Lingual Plate, or double lingual bar.
5- Replacement of all posterior teeth → Lingual plate.
6- Labial bar is rarely indicated.