JOVD 2015 #3: Assessment of 68 Prosthodontic Crowns in 41 Pet and Working Dogs (2000-2012)

Question 1

Authors?

Answer 1

Lisa Fink, DVM;

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet.

Question 2

Which of the following statement is false:

A) 27% of dogs present one or more fracture teeth.

B) 70% of working dogs have fractured canine teeth

C) Occurs in pet dogs due to cage-biting and hard treats and toys

D) Mean biting forces in human is 109 to 500 N, while in dog the mean is 256 N but can be as high as 937 N depending on chewing enthusiasm.

Answer 2

​B) is False

• Fracture teeth:
  
  • reported in 27% of dogs.
  • 25% of working dogs have fractured canine teeth due to abrasive/aggressive nature of their work.
  • Occurs in pet dogs due to cage-biting and hard treats and toys (nylon bones, deer/elk antlers, and cow hooves)
  • Canine teeth subjected to combination of compression, shear, and tensile forces; long and slender shape makes them vulnerable to fracture
  • can lead to endodontic and periapical disease, secondary periodontal disease, tooth resorption, draining sinus tracts, facial swelling, and tooth loss.
• Bite forces:
  
  • Human: as high as 740 N (mean 109 to 500 N)
  • Dog: as high as 937 N (mean of 256 N); depend on chewing enthusiasm rather than size of dog.

Question 3

What are the 2 main indications for prosthodontic crown?

Answer 3

• Prosthodontic crown:
  
  • Indications: injured teeth treated with root canal therapy (continued desiccation of dentin after root canal therapy makes the affected tooth brittle and more susceptible to fracture) or excessive abrasion at the distal aspects of vital canine teeth

Question 4

What are the advantages to add an prosthodontic crown on an endodonticaly treated tooth to have ?

Answer 4

Advantages:

• allow for occlusal forces to be distributed more evenly on the remaining tooth structure, protect injured tooth, prevent marginal leakage at underlying restoration.
• In previous human study, teeth without prosthodontic crowns were lost at a 6-times greater rate than teeth with prosthodontic crowns

Question 5

What are the materials of choice for prosthodontic crown?

What material was most oftenly used to frabric the prosthodontic crown in this study?

Answer 5

• Materials of choice (strength, flexibility): Base metals such as titanium, nickel, copper, silver, and zinc.
• In this study, the materials used for the prostho crown were
  
  • semi-precious nickel-free alloy (n=37; 54.4%);
  • non-precious nickel-free alloy (n=12; 17.6%);
  • base metal nickel-free alloy (n=9; 13.2%);
  • stainless steel (n=8; 11.8%);
  • and zirconium (n=2; 2.9%)

Question 6

What are the inconvenients of prosthodonctic crown?

Answer 6

• Inconvenient to prostho crown:
  
  • 2 anesthetic episodes needed,
  • costs
  • time “off work’’ for working dog
  • prostho crown alone will not completely eliminate risk of tooth fx, behavior modification is an integral part of success in cage-biting or aggressive dog,
  • tooth preparation can be irritating to vital pulp which could lead to irreversible pulpitis and pulp necrosis (be precautious on vital tooth with severe wear lesion)

Question 7

What was the aim of this study?

Answer 7

To evaluate the effectiveness of partial and full prosthodontic crowns in pet and working dogs.

Question 8

What was the study design?

Answer 8

• Retrospective study at Un Penn of dogs received full or partial prosthodontic crowns over a 13-year period (2000-2012).
• Inclusion criteria: complete medical and dental records; information of procedures performed, and current follow-up

Question 9

How many dogs and teeth were included in this study and what breeds were mostly represented?

Answer 9

• 41 dogs; 68 prosthodontic crowns (new prosthodontic crown on lost previously crown was counted as 2 cases)
  
  • 32 were male (78%) (23 intact, 9 castrated); 9 female (22%) (2 intact, 7 spayed).
  • 10 breeds: German shepherd (n = 22; 53.7%), Belgian Malinois (n = 10; 24.4%), mixed breed dog (n = 2; 4.9%)
  • Mean age 52.2-months (17 to 94-months SD, 22.9
  • Mean weight 34.6-kg (8.6 to 62-kg
  • 29 (70.7%) working dogs (police); 12 (29.3%) pet dogs
  • average chewing activity score of the 41 dogs was 2.7

Question 10

What % of the teeth included in this study were fracture teeth versus severe wear teeth?

Answer 10

• Indications for prostho. Crown:
  
  • tooth fracture (n=48; 70.6%) or tooth wear (n=20; 29.4%).

Question 11

In this study, what % of teeth and type of teeth were treated with full-crown versus partial-crown?

Answer 11

• Type of teeth and prostho. Crowns:
  
  • 56 full-crowns (82.4%): 63 (92.6%) on canine teeth; 5 (7.4%) on Mx PM4
    
    • 27 (48.2%) SRCT, 2 (3.6%) SRCT + post-core; 4 (7.1 %) SRCT + type I crown lengthening (gingivectomy/gingivOplasty); 17 (30.4%) SRCT + type II crown lengthening (apically positioned flap after alveolectomy/alveoloplasty), 1 (1.8%) SRCT+ post-core + type II crown lengthening; 1 (1.8%) type II crown lengthening; 4 cases (7 .1 %) no endo or perio tx.
  • 12 partial (3/4) crowns (17.6%): All canine teeth
    
    • 1 SRCT; 2 type I crown lengthening (gingivectomy/gingivoplasty); 9 no endo or perio tx

Question 12

How was crown preparation done and what type of impressions made?

Answer 12

• Crown prep.:
  
  • Horizontal margin supragingival (1-2 mm) with a chamfer configuration.
  • Vertical margin for ¾ crown with knife or feathered edge configuration (bevel 70” or greater)
  • coarse diamond-coated crown preparation bur used.
• Impressions: all 68 cases
  
  • vinyl polysiloxane putty” plus
  • full-mouth impressions with alginate; models with type IV dental stone
  • bite registration with baseplate beeswax were obtained and study.

Question 13

Is temporary crown mandatory?

Answer 13

• Temporary crowns
  
  • not necessarily required but help protect crown prep.
  • made of bis-acryl composite resin
  • put on 65 cases (95.6%);
  • endodontic access sites covered by thin layer of petroleum jelly to avoid undesired contact with temporary crown;

Question 14

To which of the 3 cement categories belong the following cement products:

Cement categories: Water-based cements, Oil-based cements; Resin-based cements

Cement products:

• ​glass ionomer,
• zinc polyacrylate,
• zinc phosphate,
• zinc oxide eugenol (ZOE),
• resin matrix with inorganic fillers

Answer 14

• Water-based cements:
  
  • contain glass ionomer, zinc polyacrylate, and zinc phosphate.
  • Have low bond to tooth structure and no anticariogenic properties.
• Oil-based cements:
  
  • Most common contain zinc oxide eugenol (ZOE) (more used as endo sealer)
  • Used for luting of temporary restorations,
• Resin-based cements
  
  • resin matrix with inorganic fillers bonded to the matrix via an organosilane coupling agent
  • are stronger (high compressive and tensile strengths) than water and oil-based cements due to their insolubility in oral fluids and molecular potential to effectively bond to dentin.
  • Used for conventional prosthodontic, inlays, bridges, veneers, and retention of orthodontic brackets
  • shows substantially less microleakage at the crown than zinc phosphate cement.
  • All 68 prostho crowns in this study were cemented with resin-based cements

Question 15

According to this study which of the following increase prosthodontic crown retention?

A) Crown preparation with a lower convergence angle and higher height/diameter ratio

B) Sandblasting inside of crown with aluminum oxide

C) Crown prep. done with coarse diamond coated bur

D) Used of resin-based cement

Answer 15

All except A) present study did not incorporate tapers, convergence angles, or height/diameter ratios into the calculations, as this information was unable to be obtained retrospectively.

• Irregularities in internal surface of prostho crown and/or outer surface of prepared crowns increased retentive strengths (mostly studied for glass ionomer); so, sandblasting inside of crown with aluminum oxide to create more retentive, roughened surface; crown prep. done with coarse diamond coated bur leaves many small horizontal grooves on the crown surface aiding retention.
• This study had low bond failure rate (4.4%) suggesting use of a resin-based luting cement in both pet and working dogs is effective under high bite forces for sustained periods of time

Question 16

When comparing this study to previous study on dogs prosthodontic crown, which of the following is true?

A) Both studies included a majority of working dog and a minority of pet dogs

B) Both studies included only canine teeth

C) Both studies included prosthodotic full-crown and partial-crown

D) Both studies included approximatly 66% of fracture tooth and 33% of wear tooth

E) Both studies had a similar successful rate

Answer 16

E) is true succes rate of 85.3% in this study and 87.8% in previous study.

Present study

Previous study

41 dogs: 29 working dogs; 12 pet dogs;

18 working dogs

68 prostho crowns: 56 full-crowns canine and PM4; 12 partial (3/4) crowns canine

41 full-crowns on canine teeth only

66% fx tooth; 33% severe wear tooth tx

33% fx tooth; 66% severe wear tooth tx

Endo and/or perio tx done in all teeth except 7.1%

63.4% had no endo nore crown lengthening

Bond failure: 3 cases (4.4%); 1 full-crown Mx Pm4; 2 partial crown on C

1 bond failure;

Fracture of tooth: 7 cases (10.3%); 6 full-crowns (1 had a post-core); 1partial crown

4 fx tooth

Successful rate of 58 cases (85.3%).

success rate of 87.8%.

Question 17

What is the conclusion of this study?

Answer 17

• Results confirm a mostly positive outcome of prosthodontic crowns, making them a practical and durable treatment option for pet and working dogs.
• More studies indicated to fully evaluate other factors associated with success/failure of prostho crowns in pet and working dogs.
• More long-term studies on the prevalence of fracture of endo treated teeth indicated to determine if placement of prostho crowns is indeed justified to reduce further structure injury of teeth in dogs

Question 18

In a retrospective study of 68 prosthodontic crowns in 41 pet and working dogs, Fink et al. found that:

A) prosthodontics crown therapy in dogs was about 85% successful

B) the rate of bond failure was highly dependant on the type of cement used

C) the likelihood of tooth fracture with after crown placement was related to the crown material used

D) Crowns are practical for working dogs, however the expense, need for a second anethesia and impracticality make them less than ideal for pets.

E) A negative aspect of prosthodontic crowns is that they do not distribute the forces experience by a tooth when biting and pull

Answer 18

A: prosthodontics crown therapy in dogs was about 85% successful

Similar to a previous study, Fink found crown to be generally successful, durable, and a practical option for previously injured teeth in working dogs and pets. All of the dogs in this retrospective study had their crowns adhered with resin based cement. Variables such as crown height:diameter and convergence angle were not taken into account, as this was a retrospective study and that information was not available.

K9 bite forces are measured up to 937N with a mean of 256N compared to human bite forced up to 740N with a mean from 100-500N

Fracture teeth are reported in about 27% of all dogs.