1. mouth preparations

what are the mouth preparations referred to in this lecture?

• surgical prep

• periodontal prep (SRP)

• restorative prep

• abutment prep

• surveyed crowns

define mouth preparations

any prep to make mouth/condition more ideal to receive framework

how long after extraction can final impression be taken for healing purposes?

2 months

what type of teeth are extracted?

• periodontally hopeless teeth

• residual roots

• detrimental to RPD design

• impacted teeth

what type of RPD is more forgiving: cast metal or resin and interim?

resin and interim 

what surgical preparations can be done for severely malposed or extruded teeth?

• extraction

• orthodontic correction

• dentoalveolar segment osteomy 

what is the goal of the surgical preparations of malposed teeth?

to normalize the occlusal plane ie no tilting and create space to set up the opposing teeth; ring clasps, enameloplasty 1-1.5 mm, ortho treatment

can you increase vertical dimension of occlusion with removable partial dentures?

no because teeth need to maintain good occlusal contacts

can you increase vertical dimension of occlusion with complete dentures?

yes need at least one edentulous arch 

what is dentoalveolar segment osteomy?

surgery to cut and realign bone, full mouth usually so fairly expensive; severely malposed or extruded teeth can involve the alveolar bone

what surgical preparation can be done for enlarged tuberosity?

not so surgical but if tuberosities touch or something you can add metal base of 1mm (can control thickness and you don’t need a lot for strength) or include metal overlay of dental teeth

what are some issues with bony exostoses or tori?

• thin and friable (easily crumbled) mucosa

• interference w path of insertion

• compromise the extension of denture components

what displaceable soft tissue are surgically prepared?

• soft flabby ridges (excessive, mobile, fibrous tissue on an edentulous ridge)

• folds of redundant tissue

• surgical stent: guide used during surgical procedures (such as implant placement or alveoloplasty) to ensure optimal bone and tissue contours for future RPD support

can muscle attachments and freni be surgically prepared for rpds?

yes

can bony spines and knife-edge ridges be surgically prepared for rpds?

yes, rounded and vestibular deepening

can ridges be augmented for rpds?

yes

what can be done for patients who have lots of missing teeth but are attached to the few remaining?

implant overdenture abutments 

what is an overdenture?

a removable dental prosthesis that rests on a few remaining natural teeth or dental implants

what is the flow of perio treatment, endodontic treatment, and prosthodontic treatment before rpd placement?

phase II perio prosth endo

what restorative prep can be done for occlusal plane modifications and correction of malposed teeth or unacceptable?

diagnostic wax-up to provide info on how much to reduce occlusally w/o potential root canal treatment

for malposed or unacceptable contour you can do enameloplasty and surveyed crowns

describe when to splint abutment teeth

50% bone loss on said abutment you can extract or splint. if it is for a interim or resin you can place splint with wrought wire as it won’t cause too much stress. if it is cast metal do not be conservative with questionable teeth bc you cant add you’s have to change entire design

what are the four points discussed on lecture slides about splinting restorative prep?

• fixed splinting w surveyed crowns 

• cast restoration

• indicated only when tooth’s bony support has not significantly compromised

• RPD like swing lock rpd or w multiple rests 

(occlusal F more evenly distributed)

common mistakes of restorative preps?

too conservative and too aggressive

what are the two issues of exposure of dentin during abutment prep?

• sensitivity 

• caries susceptibility 

what are the objectives of abutment prep?

• acceptable path of insertion (adjust guide planes as needed to optimize parallelism)

• esthetics

• comfort

• retention (undercuts)

• stability

• support 

T or F: max retention is the goal

false: 0.1 or 0.2 is the goal as to not cause perio issues 

what is the general sequence of abutment prep?

• guiding plane 

• HOC adjustment (either at guiding plate area or facial/lingual)

• retentive grooves or depressions

• rest seats 

which abutment prep?

• tooth surfaces where minor connectors or (blank) will be places; don’t want to tip bur as to not create more undercut nor over taper teeth 

• cylindrical diamond burs

guiding plane

which abutment prep?

• occlusogingivally:

  • occlusal 1/3 - 2/3 (not near gingiva)

  • create any surface 2-4 mm tall parallel to axis of the teeth 

  • flat

• faciolingually:

  • proximal surface

  • rounded in harmony w existing tooth contour

guiding plane

where are guiding plane lingual surfaces for reciprocating arms located?

with a height of 2-4mm in the middle 1/3 of clinical crown 

why guiding planes of anterior teeth established?

• to re-establish normal width

• to reduce unsightly spaces btwn tipped tooth and rpd

which abutment prep?

• tapered diamonds or burs

• permits circumferential clasp location above (blank; may change wirth guiding plane modification)

HOC adjustment

reciprocal arm (above/below) HOC

above

goal of HOC adjustment of abutment prep?

eliminate sharp facioproximal and linguoproximal line angles (most typically adjusted areas)

most common HOC adjustments of upper molar

mesiobuccal

most common HOC adjustment of premolar

distobuccal

most common HOC adjustemnt of lower molars

mesiolingual

what is the restriction of the HOC adjustment for abutment prep

0.03” (biggest undercut possible, aka 0.7mm) as it is limited by enamel thickness

what can you do if you do not have an ideal undercut for the patient and design?

add a retentive groove or depression

which abutment prep?

• increase depth of undercut 

• proportional to retention requirde

• tapered diamonds

retentive groove or depression

which abustment prep?

• max 3mm occlusogingival height

• max 4mm in mesiodistal length 

• 0.01” undercut aka 0.25 mm deep

• gently sloping and contoured, not defined

• parallel to gingival margin

• line angle area

retentive or depression grooves

smooth contours of retentive grooves and depressions mean retentive clasps (can/not) flex into and out of these indentations

cannot

which abutment prep?

• 1-1.5mm at margincal ridge

• 0.5mm deeper at deepest portion (slope down to center of tooth)

• less than 90 degrees

• #4 or #6 carbide or diamond bur

• round line angle

• tapered diamond bur

rest seats

number 4 round bur for premolar or molar of rest seat

premolar

number 6 round bur for premolar or molar of rest seat

molar

how to check depth and inclination of abutment prep?

with wax

how to finish abutment preps?

finishing and polishing with fine diamond or green stone and rubber point

which occlusal rest seat?

• 1.5 - 2 mm deep

• 3 - 3.5 mm wide

• all contours gently rounded, no undercuts

embrasure 

which occlusal rest seat?

• # 37 inverted cone or bur

• round internal line angle

• one marginal ridge to the opposite

• MD width: 2.5- 3mm

• FL width: 1.5 m

• incisogingival depth: 1.5mm

cingulum - crescent or v-shaped

which occlusal rest seat?

• axial wall: parallel to path of insertion

• gingival floor: 1 -1.5mm wide

• 90 degrees

• flat end diamond bur or tapered fissure bar

cingulum - ledge

which occlusal rest seat?

• ~ small occlusal rest seat

• #4 or #6 round bur

• marginal ridge reduction 

• junction of middle 1/3 and gingival 1/3 

cingulum - ball or lug

if you survey and cannot find good guiding plane, undercuts, etc then certain teeth should be (blank)

crowned

which mouth prep?

• crowns that are used as abutments of rpd

• more ideal retentive contour

• definite guiding plane

• optimum occlusal rest

• effective reciprocation

surveyed crown

can rest seat and guiding planes in metal and additional reduction for rest seat i the crown prep be made for surveyed crowns?

yes; additional clearance and prep to lower occlusal plane more if you add an occlusal rest

how tall are survey crown rest seats

1 - 1.5mm high into the porcelain crown for the metal rest to fit

surveyed crowns located and what does that indicate?

• crown ledge or shoulder

• restores the lingual contour

• more effective reciprocation

what do you verify before try-in?

tripoded path of insertion, guiding plane, undercut, rest seat

what to adjust on survey crown?

undercuts 0.01”, recontouring, polishing,