Analysis of the packing density of Hunter-Schreger bands (HSB): a systematic review and meta-analysis

This review examines the different configuration of Hunter-Schreger bands (HSBs), focusing on the packing density of HSBs in various regions of the tooth crown, while also considering the clinical implications. This was achieved through a systematic analysis of the literature and by performing a meta-analysis and TSA (Trial Sequential Analysis).The systematic review was conducted following the PRISMA guidelines using electronic databases such as PubMed, Scopus, Cochrane Central Register of Controlled Trials, and ScienceDirect, with the use of combinations of keywords such as 'Hunter-Schreger bands' AND 'packing densities'. The meta-analysis was performed using RevMan 5.4 software.

During the selection process, 190 records were identified, of which only 2 studies fully met the inclusion criteria, one of which presented data on packing densities in different areas of the tooth crown. The extracted data were included in the meta-analysis and TSA. The meta-analysis reported a mean difference (MD) of 4.95 [4.96, 5.22] for HSB packing density between the middle third and the cervical third of the enamel. In conclusion, HSB packing density is significantly higher in the middle region of the tooth crown, where greater occlusal forces occur. In contrast, the cervical regions, which have lower HSB density, are more susceptible to erosive and abrasive forces. These findings suggest that the spatial distribution of HSBs influences enamel resistance to mechanical stress and plays a role in the development of NCCLs.