The purpose of this split-mouth study was to compare the efficacy of using Bio-active cement versus Packable glass ionomer for cementation of posterior zirconia pediatric crowns.

Restoration of pulp treated or badly broken down deciduous teeth with full coverage restoration have shown superior success rate to all other restorative materials.

Restoration of deciduous teeth with esthetic full coverage restoration has been a challenging aim especially for the more functionally loaded posterior teeth. Due to the continuous increase in socio-economic standards; restoring posterior teeth with esthetic restoration is on high demand nowadays.

The recently introduced zirconia pediatric crowns have been very promising in terms of strength and toughness. Clinical trials on maxillary incisors have shown very high success rates in terms of retention and gingival health.

The problem of restoring posterior deciduous teeth with pre-fabricated zirconia crowns is that its retention is only and totally dependent on luting cement, in addition to the problem of the deteriorated gingival condition around crowns in general.

Being recently introduced to the market; there have not been any clinical trials studying retention of zirconia posterior pediatric crowns published yet.

Recently introduced bio-active cement [NuSmile® BioCem™] is claimed by the manufacturer to be the solution of this problem due to the shock absorbing effect, bioactive components, and antimicrobial effect making it tougher than traditional cements and more gingival friendly.

Also, experienced clinicians have found that packable glass ionomer gives very acceptable results for retention of zirconia pediatric crowns. This may be due to the fact that, pre-fabricated pediatric crown is not well adapted to the prepared tooth creating a greater gap between the prepared tooth and the crown, resulting in a greater film thickness of luting cement, which may benefit from the stronger, tougher and less soluble packable glass ionomer rather than the conventional glass ionomer cement for cementation of zirconia crowns.

There is no clear evidence whether it's better to cement zirconia based crowns with conventional or adhesive cement; and to the investigator's knowledge, there is no data available for the best clinical practice in cementation of zirconia pediatric crowns; and so, this study was carried out to compare the effectiveness of bio-active cement with packable glass ionomer when used for cementation of zirconia pediatric crowns.

Inclusion Criteria:

1. 4-7 years old patients having two contra-lateral mandibular first primary molars indicated for restoration with crowns.
2. Presence of sound tooth structure at the cervical margins of the teeth.
3. Presence of opposing functioning teeth.
4. Included teeth should be assessed clinically as free from active pulpal or periodontal conditions.
5. Patient must be in general good health, with no medical contraindication to dental treatment.
6. Patient must be available for required recalls as outlined in the protocol.

Exclusion Criteria:

1. Teeth with defects like hypoplasia or hypocalcification.
2. Patients with untreated periodontal disease.
3. Patients with any pathological or systemic problems that would not allow the dental procedures in this study to take place.
4. Teeth that exhibit mobility.
5. Patients that show signs of severe bruxism or teeth clenching.
6. Subjects with deleterious oral habits like pencil/pen chewing.
7. Uncooperative patients.