They reported that the loss of DSPP protein in DSP-PP null mice led to periodontal disease in mice.48 To further probe whether the DSP transgene in DSPP null mice could restore defective periodontium, Gibson et al. reported that overexpressing the NH2-terminal fragment (i.e., DSP protein) of DSP-PP aggravated periodontal defects in DSP-PP knockout mice.49 Thus, these authors concluded that DSP was not able to restore defective periodontium. This evidence concerns the gene DSPP and periodontal disorder.