Prevalence and patterns of dental needle tip deformation during maxillary buccal and palatal infiltration anesthesia

Needle tip deformation is a recognized occurrence during dental local anesthesia that may affect injection safety and efficacy. This study aimed to assess the prevalence, extent, and direction of needle tip deformation and its association with operator level, bone contact sensation, and injection approach in maxillary infiltration.

This cross-sectional study analyzed 180 dental needle samples, including 90 experimental and 90 control samples. The experimental group was subdivided into three injection approaches: buccal infiltration only, palatal infiltration only, and sequential buccal-then-palatal infiltration performed using the same needle. Needle tip deformation was examined using a field-emission scanning electron microscope (FE-SEM), and the extent of deformation was quantified with ImageJ software. Statistical analyses compared the prevalence, extent, and direction of deformation across practitioner levels and injection approaches.

Needle tip deformation occurred more frequently in the experimental group (55.6%) compared with controls (1.1%) (χ ² = 65.691, p < .001). No significant differences in the prevalence of deformation were observed across injection approaches (χ ² = 2.520, p = .284). Fourth-year dental students and interns demonstrated comparable rates of deformation (53.3% vs. 57.8%) (χ ² = 0.180, p = .671) and non-different extent of deformation (t = 0.588, p = .588). The direction of deformation (inward 52.2% vs. outward 47.8%) showed no significant association with operator level (χ ² = 6.523, p = .163) and no significant difference in the extent of deformation (t = -1.275, p = .209). Although the sensation of bone contact varied significantly by injection type (χ ² = 13.289, p = .004), it was not associated with actual needle tip deformation (ρ = 0.140, p = 0.189).

Needle tip deformation occurred in more than half of maxillary infiltration procedures. The prevalence and extent of deformation were not influenced by operator level, bone contact, or the infiltration approach in buccal, palatal, and sequential buccal-palatal injections. Future studies should assess patient-centered and anesthetic outcomes to determine its clinical relevance.