CHAPTER 5: MAXILLARY MAJOR CONNECTORS

6 basic types of maxillary major connectors

single palatal bar

single palatal strap

palatal plate-type connector

u-shaped palatal connector

anterior-posterior palatal bars

combination A/P palatal strap–type connector

definite tooth support

must be provided whenever it is necessary for the palatal connector to make contact with the teeth for reasons of support

accomplished by establishing definite rest seats on the predetermined abutment teeth

located far enough above the gingival attachment

to provide for bridging of the gingival crevice with blockout

located low enough on the tooth

to avoid unfavorable leverage

located low enough on the mx incisors and canine

to avoid incisal interference of the opposing dentition

results when MC components resting on unprepared inclined tooth surfaces

slippage of the denture

orthodontic movement of the tooth

ways to prevent sequelae due to gingival third trauma

provide adequate gingival relief

one should support the major connector with definite rests on the teeth

locate the connector far enough away from the gingival margin

• to avoid entrapment of food debris

• to avoid any possible restriction of blood supply

sharp & angular form

should be avoided in any portion of a palatal connector

—all borders should be tapered toward the tissue

—all gingival crossings should be abrupt and at right angles to the major connector

single palatal strap

22-gauge matte plastic pattern suitable for rigidity

bulk can interfere with speech when placed anteriorly

should not be used with anterior replacements due to torque and leverage issues

can be rigid without bulk and tongue interference if cast framework material is distributed in three planes

suitable for short-span tooth-supported bilateral edentulous areas and tooth-supported unilateral edentulous situations

combination A/P palatal strap–type connector / CAPPS

symmetrically placed components are more likely to accept by the tongue

rigid palatal major connector suitable for almost any maxillary partial denture design

maxillary major connectors should cross the midline at a right angle; not on a diagonal

strength lies in longitudinal connectors on either side, forming a square or rectangular frame

posterior connectors should be flat and 8mm wide, located posteriorly to avoid tongue interference

8mm wide

measurement for anterior & posterior part of A/P palatal strap–type connector

[ 9mm for uniformity ]

7-9mm

measurement for each side part of A/P palatal strap–type connector

[ 8mm for uniformity ]

classes II and IV

what class does combination anterior-posterior connector design mostly used

class III

what class does single wide palatal strap mostly used

class I

what class does palatal plate–type or complete coverage connector mostly used

A/P palatal strap–type major connector

anterior component — flat strap located posteriorly to avoid rugae coverage and tongue interference

posterior component — strap is thin, 8mm wide, located posteriorly on hard palate

positioned at right angles to midline, not diagonally

palatal plate–type connector

used for 7-8 remaining teeth

covers 2/3 or half of the hard palate

anterior border follows valleys between rugae

defined as thin, broad, contoured palatal coverage

posterior border located at hard and soft palates junction

in bilateral distal extension, indirect retainers are essential

anatomic replica palatal castings maintain uniform thickness and strength

provisions for a butt-type joint pass through the pterygomaxillary notch

palatal plate

the term used to designate any thin, broad, contoured palatal coverage

used as a maxillary major connector and covering one half or more of the hard palate

advantages of anatomic contours of the palate

corrugation adds strength for thinner casting

retention depends on denture base's retention

interfacial surface tension enhances prosthesis retention

allows creation of thin metal plate replicating patient's palate

surface irregularities require electrolytic polishing for uniform thickness

retention resistance is proportional to denture base contact area

forces that retention must be adequate to resist

forces of gravity

pull of sticky foods

violent forces of coughing and sneezing

action of moving border tissue against the denture

3 ways the palatal plate may be used

as a plate that covers two or more edentulous areas

as complete or partial cast plate extending posterior to hard and soft palates junction

provides anterior palatal connector with posterior acrylic resin denture base extension

complete coverage palatal major connector

terminates at the junction of the hard and soft palates

alteration of natural palatal contours can affect speech

portion contacting teeth must have positive support from rest seats

the anterior portion is supported by positive lingual rest seats on canines

crucial location of finishing lines parallel to ridge crest center and lingual to missing natural teeth

recommended for last remaining abutment tooth on class I arch side is canine or 1st premolar, especially when residual ridges have undergone vertical resorption

acrylic-resin palate

may be used when relining is expected or cost is a factor

however, cast palate is still preferable due to its advantages over acrylic-resin palate despite higher costs

2 methods used when complete coverage used for excessive vertical resorption of residual ridges

complete cast plate

acrylic-resin denture base attachment

u-shaped palatal connector

multiple tooth support can make this connector more rigid

used when large inoperable palatal torus prevents palatal coverage

less desirable from patient and mechanical standpoints due to flexibility

without support borders, gingival irritation and periodontal damage can occur

can cause movement and trauma in distal extension partial dentures without tooth support

wider coverage of this connector resembles palatal plate-type connector, but lacks necessary rigidity

common error in the design of a u-shaped connector

its proximity or actual contact with gingival tissue

principal objections to use of the u-shaped connector

bulk to enhance rigidity — increase tongue-hindrance areas

fails to provide good support — allowing tissue impingement during occlusal loading

lack of rigidity — allow lateral flexure, causing torque or direct force to abutment teeth under occlusal forces

single palatal bar

centrally located between denture halves

widely used but least logical palatal connector component

objectionable from patient comfort and alteration of palatal contours

partial dentures often too thin or bulky, objectionable to the patient's tongue

must have concentrated bulk for cross-arch stress distribution and rigidity for support and stabilization

the decision to use this bar instead of a strap:

• based on the size of the denture-bearing areas

• whether a single connector located between them would be rigid without objectionable bulk

bar

a palatal connector component less than 8 mm in width

disadvantages of combination A/P palatal bar-type connectors

exhibits similar disadvantages as single palatal bar

the anterior bar often interferes with the tongue due to its bulk and location

these connectors could be too bulky and could interfere with tongue function

beading

exclusive of rugae areas

accomplished using cleoid carver

slightly rounded groove is preferred than a v-shaped groove

care must be exercised to create a groove no larger than 0.5 mm in width or depth

used to denote the scribing of a shallow groove on the mx master cast outlining the palatal major connector

purposes of beading

to provide a visible finishing line for the casting

to transfer the major connector design to the investment cast

to ensure intimate tissue contact of the major connector with selected palatal tissue

5 basic steps of designing mx major connectors by Blatterfein

outline of primary bearing areas — those covered by denture base

outline of nonbearing areas — those lingual gingival tissue, hard areas of the medial palatal raphe, and palatal tissue posterior to the vibrating line

outline of connector areas — provides outline or designate areas for major connector components

selection of connector type — connectors should be of minimal bulk and positioned to avoid tongue interference during speech and mastication; must have a maximum of rigidity to distribute stress bilaterally

unification — after selection, denture base areas and connectors are joined

4 factors on selecting the type of connector

rigidity

mouth comfort

indirect retention

location of denture bases

double-strap type of major connector

provides the maximum rigidity without bulk and total tissue coverage

principles in designing mx major connectors

the need for indirect retention influences the outline of the major connector

location of edentulous ridge areas influences choice of major connector strap

provision must be made in the major connector so that indirect retainers may be attached

when edentulous areas are located anteriorly, the use of only a posterior strap is not recommended

when only posterior edentulous areas are present, the use of only an anterior strap is not recommended

single palatal strap [illustration]

anterior-posterior palatal strap [illustration]

palatal plate [illustration]

u-shaped [illustration]

single palatal bar [illustration]

anterior-posterior palatal bars [illustration]

single palatal strap [illustration]

anterior-posterior palatal strap of class I [illustration]

palatal major connector covering 2/3 of the palate [illustration]

palatal plate for a class I mod 1 [illustration]

complete coverage palatal [illustration]

linguoplate [illustration]

with provisions for attaching the full-coverage resin denture base

completed rpd with resin base [illustration]

u-shaped palatal [illustration]

combination anterior-posterior palatal bar [illustration]