"Vertical safety zone" as a clinical framework: Is temporarization necessary when increasing VDO within the VDR? A...

This systematic review synthesized clinical data to assess whether a temporarization phase improves outcomes compared to immediate definitive restorations when the vertical dimension of occlusion (VDO) is increased within or equal to the vertical dimension at rest (VDR). It aimed to clarify whether maintaining treatment within this physiologic range-a proposed "Vertical Safety Zone"-supports favorable restorative and functional outcomes. Following PRISMA 2020 guidelines, we searched PubMed, Scopus, Web of Science, and Embase for studies evaluating full-mouth or multi-unit rehabilitations with increased VDO ≤ VDR. Risk of bias was assessed using ROBINS-I, and certainty of evidence rated using GRADE. Meta-analysis was conducted using a random-effects model when applicable. Nine studies met inclusion criteria, with four contributing quantitative data (2,201 restorations, 3-5.5 years' follow-up). The pooled replacement-free survival rate was 97.8% (95% CI: 95.6-98.9%), and clinical success (including minor repairs) was 94.0% (95% CI: 90.5-96.5%). The annual failure rate averaged 1.28% (95% CI: 0.7-2.1%). No study reported temporomandibular or muscular complications when VDO remained within VDR limits. Temporarization protocols, when used, were typically short (< 48 h). When VDO increases are confined within the VDR, immediate definitive rehabilitation may be a viable alternative to temporarization. Although direct comparisons were limited, the findings suggest that staying within this "Vertical Safety Zone" preserves neuromuscular harmony and restoration longevity. The concept should be considered a useful framework for clinical planning, pending further controlled validation.