12. 後牙牙冠缺損僅侷限於部分的咬合面與鄰接面時,保守且合適的選項是下列何者?(A)嵌體 (inlay)(B)冠蓋體 (onlay)(C)全牙冠 (full crown)(D)陶瓷融合金屬牙冠 (porcelain-fused-to-metal crown)