This study will be conducted to:
Evaluate and compare the clinical success, periodontal changes, and wear of antagonist teeth for three types of prefabricated crowns in primary molars: BioFlx crowns, Zirconia crowns, and Stainless Steel crowns.
Children who are free from any systemic disease.
Children with a carious lower primary molar indicated for crown restoration.
Teeth with an intact antagonist and neighboring primary molar.
Cooperative children with scores 1 and 2 (positive or definitely positive) according to Frankl's behavior rating scale.
Children with extremely poor oral hygiene.
Teeth showing radiographical furcation involvement or root resorption.
Children with para-functional habits, bruxism, or deep bite.
Teeth with inadequate non-restorable crown structure.
Parallel
Preformed stainless steel crown.
Other interventionA well-fitted preformed stainless-steel crown will be chosen by measuring the mesiodistal dimension of the tooth or its contralateral counterpart, using a graduated periodontal probe for guidance. (6) Tooth preparation will be carried out with #835 diamond fissure bur to reduce occlusal surface up to 1 to 1.5 mm. The interproximal reduction will be made mesially and distally using #169 L tapered diamond bur around 0.5 mm to clear the contact area creating a feather edge finish line. The selected crown size will be checked, and a trial fit will be done before cementation. The crown will be cemented using self-cured RMGI luting cement. The excess will be removed, and proper occlusion will be checked.
Preformed zirconia crown
Other interventionThe material for crown restoration for this group is the preformed zirconia crown. Tooth preparation will be started by occlusal reduction (1 to 1.5 mm) using #835 diamond fissure bur. The interproximal reduction will be done mesially and distally with #169 L tapered diamond bur in such a way that a straight probe passes freely through the contact area. Rounding of line angles will be done and a knife-edge finish margin of the proximal surface will be obtained avoiding any ledge formation. The selected crown will be placed and checked for a passive fit. Consistent firm finger pressure will be applied during cementation with self-cured RMGI luting cement. Finally, crown placement will be checked.
Preformed BioFlx crown
Other interventionThe prefabricated BioFlx crown will be used in this group. A similar-sized preformed crown will be selected. Tooth preparation will be carried out similarly to traditional SSCs with #835 diamond fissure bur for occlusal reduction by 1-1.5 mm including the central groove. The proximal preparation will be done mesially and distally with #169 L tapered diamond bur around 0.5 mm to clear the contact area creating a feather edge finish line. Placement of the crown will be achieved by a snug fit. Crown cementation will be carried out using self-cured RMGI luting cement and the excess cement will be removed using a floss or an explorer. (13) Finally, crown placement will be checked
Crown retention
The crown retention will be measured concerning the proper adaptation of the crown or the complete crown loss according to the following: 0 = present. 1 = absent.
Color stability
The color stability will be evaluated using one crown from the original kit as a standard that will be held up to each crown restoration for color comparison according to the following: 0= Unchanged. 1= Minor deviation from original. 2 = Unacceptable discoloration.
Secondary caries
Secondary caries will be measured according to USPHS by visual inspection with an explorer to inspect if there is evidence of caries with the margin of the crown restoration according to the following: 0 = no caries 1 = caries present
Gingival Index (Periodontal Changes)
The GI (Gingival index) will be measured by the William Gingival Probe; the values will be recorded according to the following: 0 = normal gingiva 1. = mild inflammation: a slight change in color, slight edema, no bleeding on probing 2. = moderate inflammation: redness, edema, glazing, or bleeding on probing 3. = severe inflammation: marked redness or edema, a tendency toward spontaneous bleeding, and ulceration.
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