Bilateral sagittal split osteotomies versus mandibular distraction osteogenesis: a prospective clinical trial comparing inferior alveolar nerve function and complications

The aim of this study was to conduct a prospective clinical trial comparing the neurosensory function of the inferior alveolar nerve (IAN) after mandibular advancement surgery with either bilateral sagittal split osteotomies (BSSO) or mandibular distraction ostoegenesis (MDO). 23 Class II mandibular hypoplasia patients requiring mandibular advancement were randomized into two groups for either BSSO or MDO. Subjective and objective neurosensory evaluations were performed preoperatively and at the following postoperative times: 2 weeks (TBD1), 6 weeks (TBD2), 12 weeks (TBD3), 6 months (TBD4) and 12 months (TBD5). Subjective evaluation included the use of a visual analogue scale (VAS). Objective evaluation included the use of light touch (LT), two-point discrimination (2PD) and pain detection threshold (PD) tests. Intra-operative or postoperative complications were recorded. Using a mixed model, no significant differences were reported in subjective VAS scores and objective LT, 2PD and PD scores between the BSSO and MDO groups over 12 months (p > 0.05). Common postoperative complications included localized wound infection (BSSO = 2, MDO = 6) and condylar resorption (BSSO = 1, MDO = 1).     

Neurosensory and functional evaluation in distraction osteogenesis of the anterior mandibular alveolar process

Neurosensory status and craniomandibular function of 19 patients (mean age 35.2 years, range 17.8–58.8 years) treated by combined surgical orthodontic treatment with distraction osteogenesis of the mandibular anterior alveolar process (DO group) was compared with that in 41 orthodontically treated patients (mean age 22.9 years, range 15.1–49.0 years; control group). Clinical examination took place on average 5.9 years (DO group) and 5.4 years (control group) after treatment ended. Neurosensory status was determined by two-point discrimination (2-pd) and the pointed and blunt test. Lateral cephalograms evaluated advancement of the mandibular alveolar process and possible relapse. There was no significant difference in craniomandibular function and neurosensory status between the groups. Age was significantly correlated with 2-pd at the lips (DO: p = 0.01, R = 0.575; control group: p = 0.039, R = 0.324) and chin (DO: p = 0.029, R = 0.501; control group: p = 0.008, R = 0.410). Younger patients had smaller 2-pd values. Gender, age, the amount of advancement, and relapse at point B or incision inferior show no correlation with craniomandibular function and neurosensory impairment. DO of the mandibular anterior alveolar process is a valuable and safe method with minor side effects regarding neurosensory impairment.     

Long-term neurosensory disturbances after modified sagittal split osteotomy

We have investigated the long-term incidence of neurosensory disturbances after modified bilateral sagittal split osteotomy, and identified associated risk factors. We prospectively studied 376 patients, and their self-reported neurosensory disturbances were evaluated six months, and one, two, and three years postoperatively. The correlations between the following risk factors and neurosensory disturbances were investigated using univariate analysis and stepwise multivariate analysis: age at operation, sex, type of movement (advancement, setback, or rotation), concurrent genioplasty, type of detachment, iliac crest bone graft, and use of dicalcium phosphate synthetic bone graft. Probabilities of less than 0.05 were accepted as significant. Three years postoperatively, 57 patients (15%) reported altered sensation of the lower lip or chin. Older age correlated significantly with neurosensory disturbances (p < 0.0001). Greater mandibular advancement correlated with postoperative “positive” neurosensory phenomena (right side p = 0.08; left side p = 0.03). Intraoperative surgical manipulation of the left inferior alveolar nerve was significantly associated with postoperative hypoaesthesia (p = 0.014). Older age at surgery, extensive mandibular advancement, and surgical manipulation of the left inferior alveolar nerve, were associated with long-term neurosensory disturbances after modified bilateral sagittal split osteotomy. The modified operation seems to safeguard the inferior alveolar nerve from transection, without causing damage to other nerves.     

Density of the mandibular ramus (cancellous:cortical bone volume ratio) as a predictor of the lingual fracture pattern in bilateral sagittal split osteotomy

The aim of this retrospective cohort study was to evaluate the relative amount of cancellous bone in the mandibular ramus as a predictor of lingual fracture patterns after bilateral sagittal split osteotomy (BSSO). The study including 78 consecutive patients (156 osteotomy sites). In preoperative cone-beam computed tomographic (CT) scans, the volumes of cancellous and cortical bone in the BSSO surgical field were estimated. Patients were divided into two groups based on the cancellous:cortical bone ratio. We studied postoperative cone-beam CT scans for lingual fracture lines and subcategorised them according to the lingual split scale (LSS). Generalised linear mixed models (GLMM) were estimated to evaluate the association between the cancellous:cortical bone ratio and the lingual fracture pattern. There was a significant association between the cancellous:cortical bone ratio of the mandibular angle and the lingual fracture pattern after BSSO. Mandibular angles with a relatively small amount of cancellous bone showed significantly more LSS3 fracture lines (OR = 1.990, 95%CI 1.043 to 3.796, p = 0.043). These mandibular angles also showed more unfavourable fractures (LSS4), although this was not significant (OR = 2.352, 95%CI 0.748 to 7.392, p = 0.143). The relative amount of cancellous bone in the mandibular angle is significantly associated with the lingual fracture line after BSSO.     

Bilateral sagittal split osteotomy training on mandibular 3-dimensional printed models for maxillofacial surgical residents

Complications with bilateral sagittal split osteotomy (BSSO) can sometimes result from surgical inexperience. Our aim was to present a 3-dimensional printed mandibular model for BSSO training in a maxillofacial surgical education programme. A polymethacrylate mandibular model obtained from mandibular cone-beam computed tomographic (CT) images was designed and printed for use in training. Twenty-four residents were each asked to do a BSSO according to the Epker/Dal-Pont technique. The session was conducted as a simulation course with a final debriefing. A questionnaire before and after the test was filled in using a 10-point Likert scale to assess the participants’ knowledge. The mandibular model provided a realistic way of handling the trabecular bone after cortical osteotomy, as well as in the splitting phase. Significant increases in knowledge and surgical skills were noted for all steps of the BSSO, particularly regarding the use of the piezoelectric device for osteotomy, and for management of wisdom teeth in the splitting zone (3.00 ±2.16 to 6.95 ±2.06 and 2.73 ±1.91 to 5.75 ±2.63, respectively; p₁ = 0.0002 and p₂ = 0.0003). We think that this is a valuable printed mandibular model for the development of surgical skills for BSSO in maxillofacial surgical residents.     

Clinical outcomes of lingual nerve repair

Lingual nerve injury, a well-described complication of third molar removal, may result in permanent lingual sensory deficit leading to symptoms including lost or altered sensation, inadvertent tongue biting, and the development of unpleasant neuropathic pain, with consequent impaired quality of life. We analysed outcomes of a prospective case series to determine whether direct anastomosis of the lingual nerve results in improved sensory recovery and reduced neuropathic pain, and whether delayed surgery is worthwhile. In 114 patients who underwent nerve repair at our nerve injury clinic following damage sustained during mandibular third molar removal, sensory deficit was assessed before and after surgery using a questionnaire and visual analogue scales (VAS) to assess pain, tingling, and discomfort. Neurosensory tests were utilised to evaluate light touch, pin-prick, and two-point discrimination thresholds. Subjectively, 94% patients felt their sensation had improved following nerve repair, with significant reductions in the incidence of tongue biting (p < 0.0001), impaired speech (p < 0.0001), and neuropathic pain (p = 0.0017). Quantitative neurosensory data showed highly significant improvements in light touch, pin-prick, and two-point discrimination (all p < 0.0001), and VAS scores for pain (p = 0.0145), tingling (p < 0.0025), and discomfort (p < 0.0001) were significantly reduced. Patients with high levels of pain preoperatively (VAS > 40) showed highly significant reductions in pain (p < 0.0001). No correlation was found between surgical outcome and patient’s age or delay until surgery. Lingual nerve repair results in good sensory outcomes and significant improvements in the incidence and degree of neuropathic pain, even when delayed.     

Prediction of neurosensory alterations after sagittal split ramus osteotomy

Prediction of neurosensory deficit in the lower lip and chin after sagittal split ramus osteotomy (SSRO) is challenging. This study aimed to elucidate factors related to the development and improvement of neurosensory disturbance (NSD) after SSRO with respect to surgical procedure and the anatomical and structural characteristics of the craniomaxillofacial skeleton. Subjects comprised 50 patients treated by a single experienced surgeon. Anatomical data and landmarks were obtained by computed tomography (CT) imaging. There was a significant difference between patients with or without NSD for the surgical space on the medial side of mandibular ramus 1 week after SSRO (P = 0.006). Less than 15.0 mm between the lingula and mandibular notch (relative risk, 6.7; 95% CI, 1.7–33.8) and 195.0 mm² or more space on the medial side of the mandibular ramus (relative risk, 17.2; 95% CI, 3.9–100.4) indicated a significant risk of NSD development at 6 months postoperatively. These results suggested that the development of NSD is related to the surgical space on the medial side of the mandibular ramus and subsequent manipulation of the inferior alveolar nerve (IAN) in that region. Limited periosteal degloving prevents excessive stretching of the IAN during SSRO, thus lowering NSD incidence.     

In vitro enamel erosion and abrasion-inhibiting effect of different fluoride varnishes

ObjectiveTo investigate the erosion and abrasion inhibiting effect of CPP-ACP/NaF and xylitol/NaF varnishes.MethodsBovine enamel samples (n = 40) were exposed to the following treatments (n = 10): NaF varnish (Duraphat^®, positive control); CPP-ACP/NaF varnish (MI varnishTM); xylitol/NaF (Profluorid^®) or distilled and deionized water (MilliQ^®, negative control). The samples were submitted for 3 days to 4 cycles/day of erosion (5 min in Sprite Zero) and 2 cycles of abrasion/day after the first and last erosive challenge, with a toothbrush machine and slurries of a placebo toothpaste for 15 s (50 strokes/s). Among the cycles and after the last daily cycle, the specimens remained in artificial saliva. The change in the enamel surface was evaluated by using 3D non-contact optical profilometry with surface roughness (Ra and Sa values) and tooth structure loss (TSL) measurements. Scanning electron microscopy (SEM) assessed the enamel topographic characteristics. Differences in the Ra, Sa and TSL among treatments were tested using one-way ANOVA followed by the Tukey test.ResultsAll varnishes promoted better results for Ra and Sa values than the negative control (p = 0.0001), without difference among them (p > 0.05). However, CPP-ACP/NaF varnish stimulated fewer TSL (7.09 ± 0.70 μm) compared to NaF varnish (10.33 ± 1.36 μm, p = 0.002), xylitol/NaF varnish (9.96 ± 0.41 μm, p = 0.007) and the negative control (18.38 ± 3.32 μm, p = 0.0001).ConclusionA single-application of fluoride topical varnishes was effective in reducing enamel wear. The CPP-ACP/NaF varnish had the best effect against enamel loss from an erosion-abrasion challenge.     

Probiotic consumption decreases the number of osteoclasts during orthodontic movement in mice

AimsThe aim of the present study was to investigate the effect of probiotic (Bacillus Subtilis) supplementation on bone remodelling induced by mechanical loading.MethodsC57BL/6 mice were divided in two groups: (1) Probiotic and (2) Vehicle (water). The probiotic (1.5 × 10⁸ CFU/mL) was administered orally for 14 days, starting two days before the induction of orthodontic tooth movement (OTM). OTM was determined by histomorphometric analysis by comparing the right to the left side of the maxilla. The number of osteoclasts was determined by counting TRAP-positive cells. Osteoblasts were counted on Masson’s trichrome-stained slides.ResultsOTM was similar between groups (with and without probiotic supplementation) (p = 0.46). The number of TRAP-positive cells increased (p < 0.01) on the experimental side (where the spring coil was installed) in comparison to the control side in both groups. However, the number of osteoclasts decreased (p ˂ 0.01) in the probiotic group, in comparison to the vehicle group. There was an increase in the number of osteoblasts (p ˂ 0.05) in both the Vehicle and Probiotic groups on the side under OTM, independent of probiotic supplementation.ConclusionOral Supplementation with a probiotic influenced the number of osteoclasts adjacent to the tooth root during orthodontic movement in mice.     

Antibiotic prophylaxis for bilateral sagittal split osteotomies: a randomized,double-blind clinical study

The goal of this study was to determine the efficacy of one dose and a short course (3 doses) of amoxycillin therapy for the prevention of infection following bilateral sagittal split osteotomy (BSSO). Patients who qualified for the trial were randomly divided into two groups: group I patients were given a single injection of amoxycillin 1.0 g administered preoperatively followed by two postoperative doses of saline four hourly (single dose group); group II patients were given single injection amoxycillin 1.0 g administered preoperatively followed by two postoperative doses of amoxycillin 0.5 g four hourly. The 60 patients included in this study were divided into two groups of 30. The patients were evaluated for 2 months for postoperative infections. In the postoperative period, six patients required rescue antibiotics in the single dose group and one in the short course group (P = 0.04). There was a statistical difference in the rates of infection between the two groups (P = 0.04). The findings indicate that a short postoperative course of antibiotics is more effective than a single preoperative dose for the prevention of infection following BSSO.     

Investigation into the validity of WearCompare,a purpose-built software to quantify erosive tooth wear progression

ObjectivesThe use of surface matching software with intraoral scanners is developing rapidly which increases the need for accessible, accurate and validated measurement software. This investigation compared the current gold-standard Geomagic Control software to a purpose-built software “WearCompare”.MethodsArtificially created occlusal defects of a known size were created on 10 natural molar teeth scanned with a structured-light model-scanner (Rexcan DS2, Europac 3D, Crewe). The volume change, maximum profilometric loss and mean profilometric loss were obtained from both Geomagic Control (3D Systems, Darmstadt, Germany) and WearCompare (leedsdigitaldentistry.com). Duplicated datasets were randomly repositioned and re-alignment performed. The effect of the re-alignment was calculated by analysing differences between the known defect size and defect size after re-alignment using the same measurement metrics. Lastly, clinical wear measurements were compared on natural molar surfaces (n = 60) over 6 months using study models collected from a previous longitudinal trial. Data analysis was performed in SPSS v25 (paired t-tests, Pearson correlations, p < 0.05).ResultsMeasurement correlation between the softwares was greater than 0.97 (p < 0.001) for all measurement metrics. The volume change error (SD) after alignment was −0.67 mm³(1.14) for Geomagic and −0.06 mm³(0.93) for WearCompare (p = 0.140 and r = 0.065, p = 0.86). Measurement errors were observed after alignment in both softwares and no statistical differences were observed between softwares. The volume change on the clinical dataset over 6 months was +0.29 mm³(3.97) in Geomagic and −0.30 mm³(1.82) for WearCompare (p = 0.19 and r = 0.61, p < 0.001). The mean profile gain was 42.86 μm(40.19) for Geomagic and 32.17 μm(23.72) for WearCompare (p = 0.048). Correlations between the softwares were greater than 0.6 for all measurement metrics except for mean profile gain.SignificanceWearCompare is a comparable tool to Geomagic for quantifying erosive tooth wear. WearCompare reported statistically less profile gain indicating less error but further research is needed to reduce the human errors in both softwares.     

Does the habitual mastication side impact jaw muscle activity?

ObjectiveTo compare electrical activity in the anterior temporal and masseter muscles on the habitual (HMS) and non-habitual mastication side (NHMS), during mastication and in the mandibular postural position. In addition, the increase in electrical activity during mastication was assessed for the HMS and NHMS, analysing both working (WSM) and non-working side during mastication (NWSM).MethodsA total of 28 healthy women (18–32 years) participated in the study. They were submitted to Kazazoglu’s test to identify the HMS. Bioresearch ‘Bio EMG’ software and bipolar surface electrodes were used in the exams. The exams were conducted in the postural position and during the unilateral mastication of raisins, on both the HMS and NHMS. The working and non-working side on HMS and NHMS were assessed separately. The obtained data were then statistically analysed with SPSS 20.0, using the Paired Samples Test at a significance level of 95%.ResultsThe differences in the average EMG values between HMS and NHMS were not statistically significant in the postural position (Temporal p = 0.2; Masseter p = 0.4) or during mastication (Temporal WSM p = 0.8; Temporal NWSM p = 0.8; Masseter WSM p = 0.6; Masseter NWSM p = 0.2). Differences in the increase in electrical activity between the masseter and temporal muscles occurred on the working side, on the HMS and NHMS (p = 0.0), but not on the non-working side: HMS (p = 0.9) and NHMS (p = 0.3). The increase in electrical activity was about 35% higher in the masseter than in the temporal muscle.ConclusionsMastication side preference does not significantly impact electrical activity of the anterior temporal and masseter muscles during mastication or in postural position.     

Combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine

ObjectiveThis study evaluated the combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine.DesignSixty slabs of bovine root dentine (2 × 2 × 2 mm) were eroded with citric acid 0.3% (pH 3.2) during 2 h and then kept in artificial saliva during 24 h. Specimens were randomly assigned in 6 groups (n = 10), to receive the following treatments: fluoride varnish; fluoride varnish + Er:YAG laser; fluoride varnish + Nd:YAG laser; non-fluoride varnish; non-fluoride varnish + Er:YAG laser; non-fluoride varnish + Nd:YAG laser. The Er:YAG (100 mJ, 3 Hz) and Nd:YAG (70 mJ, 15 Hz) were applied for 10 s. Specimens were subjected to further erosive challenges with citric acid 0.3% 4×/day, during 1 min, for 5 days, remaining in artificial saliva between cycles. Dentin permeability was then assessed. Two-way ANOVA demonstrated no significant interaction between laser and varnish (p = 0.858).ResultsNo effect was also detected for the main factor varnish (p = 0.768), while permeability of eroded root dentin was significantly lower when such substrate was laser-irradiated, no matter the laser source (p < 0.001).ConclusionsThis study concluded that Er:YAG and Nd:YAG lasers can be employed to control the permeability of eroded root dentin, regardless of fluoride varnish application.     

Effect of fixation method on intergonial width stability after mandibular setback via bilateral sagittal split osteotomy

Q4: Horizontal changes occur following bilateral sagittal split osteotomy (BSSO) in skeletal class III patients. The aim of this study was to assess the ostoperative changes in intergonial (IG) width and compare them between the positional screw and miniplate fixation methods in BSSO. This study evaluated patients who had mandibular prognathism and underwent BSSO for mandibular setback. Internal fixation was performed bilaterally, either with positional screws in the lateral ramus or with a miniplate. Postero-anterior cephalograms were obtained preoperatively (T1), at 1 month postoperative (T2), and at 6 months postoperative (T3). The IG widths and the alterations in IG width postoperative (T2 − T1, T3 − T2) were measured. No correlations were observed between the amount of setback and changes at T2  − T1 or T3 − T2. The IG width values decreased after mandibular setback and internal fixation with both methods. Statistical analyses showed a significant difference between T3 and T1 in the miniplate group (P = 0.045). No significant difference in the postoperative change in IG width (T2 − T1 and T3 − T2) was found between the two fixation groups. The magnitude of this change was smaller for positional screws when compared to miniplates for fixation. The amount of mandibular setback showed no correlation with postoperative changes in IG width..     

Treatment outcome of the two-part semi-rigid oral appliance in obstructive sleep apnea

AimThe aim of this study was to assess the effectiveness of the two-part semi-rigid oral appliance, Silensor^® (Erkodent, Tuttlingen, Germany) which prevents the mandible from retracting during mouth opening.Materials and methodsTen patients with mild or moderate obstructive sleep apnea (2 males and 8 females; mean age = 62.5 ± 10.0 years) were recruited and lateral cephalometric radiographs were taken. The patients underwent polysomnography before and after 3 months of receiving treatment with the Silensor^®. The relationship between the improvement in the polysomnographic variables after the therapy and the cephalometric features was analyzed.ResultsA significant difference was observed in the apnea–hypopnea index after 3 months of Silensor^® therapy (1st (baseline), 17.1 ± 5.5; 2nd (therapy of Silensor^®), 11.0 ± 7.2, p = 0.011). Furthermore there was a significant positive correlation between the improvement in the degree of slow wave sleep (%) and the mandibular plane angle (R = 0.662, p = 0.037), as well as between the improvement in degree of slow wave sleep (%) and the lower face height (R = 0.845, p = 0.002). A significant negative correlation was observed between the improvement in degree of sleep efficiency (%) and the soft palate area (R = ?0.809, p = 0.005).ConclusionThese results suggested that keeping the nasopharyngeal airway space during mouth opening improves apnea–hypopnea index of some patients with mild or moderate obstructive sleep apnea and quality of sleep in obstructive sleep apnea patients with a long lower face height and a small soft palate.     

Hyaluronic acid on collagen membranes: An experimental study in rats

ObjectiveThe aim of this study was to evaluate the effect of hyaluronic acid (HA) in the structure and degradation patterns of BioGide^® and OsseoGuard™ collagen membranes. HA mediates inflammation and acts in cell migration, adhesion, and differentiation, benefitting tissue remodeling and vascularization. These are desirable effects in guided regeneration procedures, but it is still unknown whether HA alters the barrier properties of absorbable membranes.DesignBone defects were created in the calvaria of rats, which were treated with HA gel 1% (HA group) or simply filled with blood clot (control group), and covered with BioGide^® or OsseoGuard™. The animals were euthanized after 1, 30, and 60 days, and their calvarias were processed for histological analysis.ResultsBioGide^®, in both HA and control groups, showed vascularization, intense cell colonization, bone formation, and tissue integration at 30 and 60 days. In contrast, Osseoguard™ presented minimal cellular colonization, and inflammatory reaction associated to foreign body reaction in both time points and groups. The HA group of BioGide^® showed higher cell colonization (574.9 ± 137.6) than the control group (269.1 ± 70.83) at 60 days (p < 0.05). Despite this finding, the structure and degradation pattern were similar for BioGide^® and Osseoguard™ in the HA and control groups.ConclusionThe results suggest that HA did not interfere with tissue integration and structural degradation of BioGide^® and Osseoguard™ membranes.     

The effect of a hydroxyapatite impregnated PCL membrane in rat subcritical calvarial bone defects

ObjectiveThe present study evaluated the effect of polymeric-nanofibers membranes impregnated with microparticulate hydroxyapatite (HA) in the subcritical calvarial bone defects (SCBD) healing.DesignPCL membranes with and without HA were obtained by electrospinning. SCBD were perforated (3.3 mm) in left and right sides of 36 rat calvarias. The right-side SBCD of 18 animals was filled with HA mixed with blood clot and blood clot at the contralateral side. The remaining animals received PCL + HA membrane at the right-side SCBD and PCL membrane at the contralateral side. Animals were killed after 30, 60 and 90 days after surgery. Bone defect volume (in mm³) was measured by tomography (CBCT). Qualitative histological analysis and SBCD area (in mm²) were measured. Quantitative data were submitted to Kruskal-Wallis/Dunn tests.ResultsReduction of SBCD volume was observed in all treatments but PCL. Association with HA significantly improved bone healing induced by PCL and blood clot. PCL + HA induced the lowest SBCD volume at 60 and 90 days. Complete bone healing was not observed even at 90 days in SCBD treated with blood clot. In every period, more bone formation was observed for SCBD treated with membranes.ConclusionsWe concluded that both PCL membrane and HA were able to improve bone healing.     

Comparison of intraoperative outcomes with single and double puncture techniques of arthrocentesis of the temporomandibular joint

Evidence of differences in operator-related outcomes between single and double puncture arthrocentesis is limited. The purpose of this prospective study was to compare intraoperative outcomes with single puncture types 1 and 2, and double puncture, arthrocentesis. A total of 59 patients with 60 temporomandibular joints (TMJ) were treated sequentially by single puncture type 1 (n = 20), single puncture type 2 (n = 20), and double puncture arthrocentesis (n = 20). Total operating time, incidence of dislocation of the needle, preauricular swelling, and ease of operation were compared. Single puncture type 2 arthrocentesis took significantly less time than type 1 (p < 0.0001) or double puncture arthrocentesis (p < 0.0001), but there was no difference in operating time between single puncture type 1 and the double puncture technique (p = 0.25). There were significantly fewer dislocations of the needle with single puncture type 1 (p = 0.041) and single puncture type 2 (p = 0.033) than with double arthrocentesis. Single puncture type 2 arthrocentesis was easier than the single puncture type 1 (p = 0.001) or double puncture technique (p < 0.0001). Extravasation of fluid caused swelling in seven patients after double puncture, and in three patients each after single puncture types 1 and 2, arthrocentesis. Our results indicate that the single puncture type 2 technique is easiest and requires the least operating time. There was no difference between single puncture type 1 and double puncture arthrocentesis in terms of operating time or ease of the procedure. There were fewer operative dislocations of the needle with the single than with the double puncture technique.