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Images at SEM of different dental needles. Images A, B, C, and D illustrate all groups of new dental needles. Images A1, B1, C1, and D1 depict bevel deformation after one infiltration. Images A2, B2, C2, and D2 showed bevel deformation after two infiltrations.
Source publication
Objectives: To evaluate quantitatively deformation of the angle of the horizontal plane of the bevel tip in new dental needles and in dental needles used in clinical procedures. Material and Methods: A cross-sectional study was performed with 360 dental needles from four different manufacturers. The needles were divided into four groups (90 per gro...
Context in source publication
Citations
... This shared observation underscores the broader context of needle deformations in various local anesthesia methodologies [9]. The widespread occurrence of needle deformation, as described by various researchers, reaching up to 100% of cases in dental local anesthesia, highlights a common phenomenon across different studies and underscores the importance of understanding and addressing this issue in dental practice [9,10,22]. The primary source of needle tip deformation is likely the contact between the needle and bone during anesthesia procedures, a factor that is inherent in various techniques, including ILA. ...
Objectives
This in vivo study aimed to assess the impact of needle bevel design on puncture pain, anesthetic success, and mechanical deformations in intraligamentary injection (ILA) cases, comparing a short triple facet cut (STF) to a triple lancet cut (TL) after single or repetitive use.
Materials and methods
In a prospective single-blind trial, 200 ILA needles (STF, n = 100; TL, n = 100) were randomly assigned for dental procedures. Patients received ILA either with STF or TL needles, used once (group A; n = 50 each) or repeatedly (group B; n = 50). Puncture pain was assessed using a numerical rating scale (NRS). Anesthetic success was determined via cold spray (yes/no), and scanning electron microscopy (SEM) analyzed needle tip deformations.
Results
Puncture pain did not significantly differ between STF and TL, regardless of needle use or injection area. Success rates were comparable in single use (82% STF vs. 79% TL; p > 0.05). For repetitive use, STF exhibited a significantly higher success rate (80% vs. 69%; p = 0.012). Mechanical deformations were prevalent in 97.5% of needles, with TL showing greater deformations than STF after single and repeated uses. Barbs were more common in TL (90/100) than STF (84/100), with a higher relative risk for barbed-like deformation in TL (RR single use: 1.26; p < 0.001; multiple use: 7.87, p < 0.001).
Conclusions
The short triple facet-designed bevel demonstrated significantly less mechanical deformation, suggesting potential advantages in maintaining needle lumen patency.
Clinical relevance
The intraligamentary needle bevel design is linked to mechanical deformation and anesthetic success after repetitive use, but not to puncture pain.
... This work focuses on geometric bent defects of needle tips, because the defect identification of bent needles is important for the application in that the IVF needles under study are thick gauge needles so sharpness is critical to ensure the best outcomes for patients. Bend angle is a common variable to evaluate the deformation of bevelled needle tips [27,28]. The other defective feature variable, bending length, , is identified through quality control inspection in the production line, because the location where a tip bend starts affects the quality control inspection outcome as the closer to the tip end the weaker the bevel strength and the higher the chance for the needle tip to fail. ...
The manufacture of In Vitro Fertilization (IVF) needles is subject to the most stringent quality demands. This makes automated inspection challenging due to difficulty in reliably classifying conforming and non-conforming (defective) products due to factors including multidimensional variation of their tip geometry and the lack of an explicit quality standard. In addition, developing an IVF needle image dataset, which broadly contains the visual characteristics of qualified and defective products, is difficult without commissioning large and costly production runs. The most important original contribution of this work is a new solution to investigate and quantify the uncertainty in the quality standard of IVF needles by integrating inter-disciplinary techniques. This work utilizes a low-cost, virtual dataset of synthetic images, generated by the automated photo-realistic rendering of a three-dimensional (3D) parametric model to simulate manufacturing variation. Then, the unknown numerical (critical) quality thresholds are obtained by estimating the relationship between quality response and measurement predictors using an Ordinal Logistic Regression (OLR) algorithm on the synthetic images. The fitted models exhibited increased overall predictive accuracy of up to 11.02% than the machine learning models (available in MATLAB) and could provide objective guidance on classifying specific quality aspects of a product.
... All of the selected commercial needles are intended for single use only. Reports have shown that a needle tip can deteriorate after multiple insertions, which might lead to an increase in the maximum insertion force [23,24]. We tested this but did not observe an increase of insertion force during 100 insertions in tongue tissue. ...
This study reports on the effects of insertion velocity, needle tip geometry and needle diameter on tissue deformation and maximum insertion force. Moreover, the effect of multiple insertions with the same needle on the maximum insertion force is reported. The tissue deformation and maximum insertion force strongly depend on the insertion velocity and the tip geometry. No correlation was found between the outer diameter and the maximum insertion force for small needles (30G – 32G). The endurance experiments showed no remarkable difference in the maximum insertion force during 100 insertions.
... The IANB is the most frequently used technique in endodontics for anaesthetising mandibular molar teeth (2) and is associated with a broad spectrum of reported failure rates from low teens to as high as 81% (2). These failures have been attributed to many factors including anatomic variability, treatment type, pathological and psychological causes (3). As a result of anaesthetic inadequacy or failure, subsequent IANB injections are often given without replacement of the needle (3,4), and following unpublished investigation by the authors, this practice is widely and consistently propagated by the majority of the 9 universities teaching dentistry in Australia. ...
... These failures have been attributed to many factors including anatomic variability, treatment type, pathological and psychological causes (3). As a result of anaesthetic inadequacy or failure, subsequent IANB injections are often given without replacement of the needle (3,4), and following unpublished investigation by the authors, this practice is widely and consistently propagated by the majority of the 9 universities teaching dentistry in Australia. ...
... Previous clinical human studies have consistently confirmed the presence of needle tip deformation following the use for dental local anaesthesia (3,4,6). There is a sparsity of information, however, relating to the influence of bevel orientation on this deformation during standard IANB administration where bone is contacted. ...
The study aimed to investigate whether any correlation existed between bevel orientation and needle tip deformation following the administration of a standard inferior alveolar nerve block (IANB) technique during patient treatment. Ninety‐three needles of a single brand were collected from a group of eleven similarly trained Australian dentists’ following either single or dual insertion and bone contact. Specimens were examined under scanning electron microscopy at 500x, and both the direction of deformation (either towards or away from lumen) and the extent of deformation were calculated using image processing software. Results showed no correlation between bevel orientation and either the direction (P = 0.8787) or degree (P = 0.0752) of deformation. Significance was demonstrated, regardless of bevel orientation, following multiple needle use with respect to extent of needle tip deformation (P < 0.0001). A clinical recommendation can be made that the dental needle should be routinely replaced when subsequent injections are required during the delivery of a typical IANB.
Introduction
The aim of this in vitro study was to investigate the mechanical deformation rate of dental cannula tips after injection simulation in a new developed animal model.
Materials and methods
A new mechanical device was designed to define forces (100g for 60 seconds) to impact a pigs jaw bone with different cannulas (25-Gauge/27-Gauge) from dental local anaestesia syringes. 8 different products (100 cannulas each) were evaluated. Cannula tips were examined for deformation under the digital microscope VHX-100 (500-fold magnification).
Results
27G and 27G free flow showed a significantly lower likelihood of bending (OR 0.05; p = 0.0001). Comparing 27G cannulas of the same outer diameter but different inner diameter, large inner diameter produced a significantly higher deformation rate than those of cannulas with a standard inner diameter. 12–38% of the cannulas showed manufacturing defects and production-related deformation.
Conclusions
Cannula deformation seems to depend on the inner diameter, bevel and cutting profile. Multiple use of the same cannula could result in more pronounced deformation, increasing the risk of complications during local anesthesia.
