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To reduce the radiation dose in dental computed tomography (CT), backprojection-filtration (BPF) algorithm is the preferred choice as it can reconstruct images from truncated data within limited scanning angle, thereby reducing radiation dose and avoiding irradiation to the brain. However, the integral interval of backprojection is variable for every PI-line which causes the calculation efficiency and parallel performance to be low. In this paper, the tent BPF method (T-BPF) was developed, which was performed by firstly rearranging the cone-beam data to tent-like parallel-beam data, and then applying the proposed BPF-type algorithm to reconstruct images from the rearranged data. T-BPF turns the variable integral interval of backprojection into fixed integral interval, which means the reconstruction efficiency and the parallel performance of T-BPF are improvements over those of the original BPF algorithm. The experiments of numerical simulation and real data reconstruction show that the reconstruction efficiency of T-BPF is faster than the original BPF algorithm and the FDK algorithm in the case of comparable reconstruction quality. The results demonstrate that the proposed T-BPF is good at achieving fast low-dose reconstruction from truncated projection data in dental CT.