cement is not only the retention factor of the fixed prosthesis, there are other more important factors:

-over tapered preparations, short clinical crown, leakage or open margin, recurrent caries and technique of cementation.

for example, In case of resin cement, contamination with PVS impression material or temporary cement might affect the polymerization which lead to cementation failure.

Hi,

Failure in cementation may b classified in to 2 types such as cohesive and adhesive failure. cohesive failure occurs with in cementing agent itself and whers as adhesive failure could occur at the cement-natural tooth interface and/or cement and the prosthesis.

The success rate of cementation depends on the skills of the operator to chose a suitable cementing agent and also depends on design of the tooth preparation.

Cementation failure in fixed partial denture is not due to type of cement used but there are several factors which govern the selection should be considered before its selection. Occlusion, chewing habits, type of food, crown height, remaining tooth structure after preparation, resistance and retention form, sharp line angles and point angles in preparation also effect the longevity of cementation.........

Film thickness, forces at the interphase , forces in the cement layer play an important role apart from the above sited reasons by others

there are many factors play a role in cementation failure in fixed partial denture. As reported in on retrospective analysis involving 638 patients, failure in cementation was found higher in men than in women, eledery patients higher than in younger patients, maxillary failure higher than in mandible, failure in bridge was lower than in single crown, and as load increase the failure increase, so the failure in posterior teeth is higher than anterior. also is high in cantilever FPD... the technique of restoring the teeth before crowning is also important, as with post and core restored teeth.

Well, there are many factors.  The selection of a suitable cement would be the most important aspect. Use of manufacturer's recommendations are to be followed. Other factors would include the resistance to salivary and acid dissolution of the cement. The preparation height, taper and width. Use of boxes and grooves could help in retention and resistance of a FPD.

Can you share some reference supporting main causes of cementation failure? thanks in advance

Causation is the most difficult aspect to prove. There are no clinical studies that admitted a poor preparation, an ill-fitting restoration and/or an occlusal prematurity on insertion.

All too often, we hear that a certain cement will be beneficial in scenarios where an ideal preparation is not possible. Sorry, in the hands of a capable clinician this rarely ever happens. Is the cement an excuse for a poor preparation or poor laboratory work?

I agree with many of my colleagues who responded previously.

Cement is the least important factor in a de-cementation failure. That assumes correct utilization. Properly mixed (if necessary) and applied. Intaglio surface of the restoration cleaned and dried. Teeth dried and isolated. Cement allowed to set, etc. All clinician variables.

Those of us that practiced with zinc phosphate cement and did not have clinical problems when correctly utilized will attest to this fact. Gravity is a great clinical guide. If you are fitting a maxillary full coverage restoration and it falls out without a lining to hold it in place, it will eventually fail. If you anesthetized the patient at the try in session there is little chance that you will have all of the occlusal issues resolved at that session.

PS – electric toothbrushes cause vibration. Ask if the patient uses one, especially if they have implants.