Evidence of Nasal Cooling and Sensory Impairments Driving Patient Symptoms With Septal Deviation.

OBJECTIVES/HYPOTHESIS: About 260,000 septoplasties are performed annually in the US to address nasal septal deviation (NSD). Yet, we do not consistently understand what aspects of NSD result in symptoms. STUDY DESIGN: Blinded cohort study. METHODS: Two fellowship-trained surgeons blindly reviewed computerized tomography (CTs) of 10 confirmed NSD patients mixed with 36 healthy controls. All patients were correctly identified, however, 24/36 controls were falsely identified by both surgeons as patients (33.3% specificity), which were grouped as asymptomatic NSD (aNSD), while the remaining controls as non-NSD (healthy). Acoustic rhinometry, rhinomanometry, individual CT-based computational fluid dynamics and nasal sensory testing were applied to address the puzzling questions of why these aNSD had no symptoms and, more fundamentally, what caused symptoms in sNSD patients. RESULTS: aNSD reported no nasal symptoms - Nasal Obstruction Symptom Evaluation score (sNSD: 60.50 ± 13.00; aNSD: 5.20 ± 5.41; non-NSD: 6.66 ± 7.17, P < .05); 22-item Sino-Nasal Outcome Test score (sNSD: 32.60 ± 14.13; aNSD: 10.04 ± 10.10; non-NSD: 9.08 ± 12.42, P < .001). No significant differences in measured nasal resistance, minimum cross-sectional area (MCA), degree of septal deviation, and nasal airflow distributions were found between sNSD and aNSD groups. Only three variables differentiate sNSD versus aNSD: anterior averaged heat flux on deviated side, inferior turbinate peak heat flux on non-deviated side, and nasal cool sensitivity measured by menthol lateralization threshold, with no significant differences among these variables found between the two healthy groups (aNSD vs. non-NSD). These variables by themselves or combined can differentiate sNSD from controls with higher specificity than the physicians (ROC area under the curve = 0.84 with 70% sensitivity and 91.6% specificity). CONCLUSIONS: This study sheds light on the potential mechanisms of NSD symptomatology: distorted nasal cooling due to NSD exacerbated by poorer nasal mucosal sensitivity. It further supports our previous hypothesis that nasal obstruction complaints do not result directly from obstruction, rather from the capacity of our nose to subjectively sense airflow cooling. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:509-517, 2022.

The Effect of Nasal Septal Deviation on the Postoperative Hearing Results of Patients With Tympanosclerosis.

OBJECTIVE: The main aim is to discuss the effect of nasal septal deviation on the postoperative hearing results of patients with tympanosclerosis. MATERIAL AND METHODS: We analyzed the hearing results of patients with tympanosclerosis who were operated on in a tertiary center. Pure tone audiometric results were compared according to the existence of nasal septal deviation. RESULTS: This study included 48 patients with unilateral tympanosclerosis disease. Moderate or severe septal deviation had no significant effect on postoperative hearing results. CONCLUSION: The nasal septal deviation as the only pathologic factor in patients with tympanosclerosis did not have a deteriorating effect after surgery.

Impact of Varying Types of Nasal Septal Deviation on Nasal Airflow Pattern and Warming Function: A Computational Fluid Dynamics Analysis.

Nasal septal deviations (NSD) have been categorized into 7 types. The effect of these different deviations on airflow pattern and warming function has not been fully investigated. The purpose of this study was to utilize a computational fluid dynamics approach to assess the impact of NSD of varying types on nasal airflow and warming function. Patients with each type of NSD were enrolled in the study, and a normal participant as the control. Using a computational fluid dynamics approach, modeling of nasal function was performed. Indices of nasal function including airflow redistribution, total nasal resistance, airflow velocity, and airflow temperature were determined. Among all types of NSD, the maximal velocity and total nasal resistance were markedly higher in type 4 and 7 deviations. The flow partition and velocity distribution were also altered in type 4 and 7 as well as type 2 and 6 deviations. Airflow in all categories of NSD was fully warmed to a similar degree. From a computational aerodynamics perspective, the type of septal deviation may contribute to altered airflow characteristics. However, warming function was similar between septal deviation types. Future studies will help to ascertain the functional importance of septal deviation types and the applicability of these computational studies.

Olfactory and Gustatory Function in Patients With Different Types of Maxillofacial Trauma.

OBJECTIVES/HYPOTHESIS: To investigate olfactory and gustatory function in patients with maxillofacial trauma and associated fractures. STUDY DESIGN: Retrospective cohort study. METHODS: Olfactory and gustatory function was assessed psychophysically in 124 patients who had sustained maxillofacial trauma with an associated fracture. Five groups were defined based on the fracture type: Le Fort, mandibular, nasal, orbital, and zygomatic. Olfaction was measured with Sniffin' Sticks (threshold, discrimination, identification [TDI] score) and gustation with the taste spray method. Patients self-rated olfactory and gustatory function on a visual analog scale prior to formal testing. RESULTS: Ten out of 124 patients were found to be anosmic (8%), with half of them found in the Le Fort (skull base) group. The Le Fort fracture group had significantly lower olfactory function than other fracture types (TDI score = 22.4 ± 10.7; P = .01; possible range = 1-48). The mean gustatory spray test score was 3.82 ± 0.4 (possible range = 0-4) without any intergroup differences. Self-rated olfactory function showed a correlation with the measured scores (r = 0.61, P < .001) across all groups. CONCLUSIONS: The present data show a significant effect of maxillofacial fracture type on the development of anosmia. Maxillofacial fractures involving the skull base, such as Le Fort fractures, are more likely to cause permanent smell loss, whereas the other fracture types are rarely associated with anosmia. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E331-E337, 2021.

The Impact of Septoplasty Operation on Odor Threshold Score and Symptom Severity According to the Nasal Septum Deviation Classifications.

OBJECTIVE: The authors aimed to determine the changes in the odor threshold and sinonasal outcome test-22 scores of the patients after septoplasty surgery in terms of nasal septum deviation classifications. METHODS: Forty-nine patients with nasal septum deviation, aged between 17 and 65, were included in our study. The sinonasal outcome test-22 scores questionnaire and the N-Butanol Threshold test were administered to the patients, 2 days before and 2 months after the septoplasty. RESULTS: The authors' study had 4 major findings: Odor threshold scores improved after septoplasty operation both for the narrower and the wider side of the nasal airway passage. The Vidigal classification for nasal septum deviation was best for predicting the changes for odor threshold scores after septoplasty operation. The nasal septum deviation in which the nasal septum was pushing the inferior turbinate to lateral nasal wall caused the most smell dysfunction according to the Vidigal classification. Unilateral vertical crest affecting the nasal valv area or the posterior part of the septum had the most negative effect on olfactory functions according to the Mladina classification. CONCLUSION: Septoplasty operation leads to improvement in odor threshold scores, and the Vidigal nasal septum deviation classification was best in predicting postoperative odor threshold changes.

Correlations between computational fluid dynamics and clinical evaluation of nasal airway obstruction due to septal deviation: An observational study.

OBJECTIVES: The primary objective of this study was to determine how computational fluid dynamics (CFD) could be correlated to clinical evaluation of nasal airway obstruction (NAO) in a population of patients with symptomatic septal deviation (SD). The secondary objective was to determine whether CFD could define which side was the more obstructed. DESIGN: This was an observational study. SETTINGS: Few publications have attempted to correlate CFD with clinical evaluation of NAO. This correlation would permit validation and improved interpretation. This study was performed in a university research laboratory specialised in fluid mechanics. PARTICIPANTS: We included patients referred for septal surgery at our centre. Age range was 19-58 years. Preoperative CT scans were performed. All patients with non-structural causes of NAO such as rhinitis, sinusitis or tumoral/autoimmune processes (ie, not due to anatomic obstruction) were excluded. MAIN OUTCOME MEASUREMENT: For each nasal fossa, we compared CFD data (total pressure, heat flux, wall shear stress, temperatures, velocity and nasal resistances) with both patient perception scores and rhinomanometry using the Spearman correlation test (rs ). Perception scores were graded from 0/4 to 4/4 on each side, based on the patient interview. We also compared CFD-derived nasal resistances with rhinomanometry-derived nasal resistances. RESULTS: Twenty-two patients complaining of NAO with SD were analysed, and 44 analyses were performed comparing each side with its CFD data. Regarding correlations with patient perception scores, the best values we found were heat flux measures (rs  = 0.86). Both rhinomanometry and CFD-calculated nasal resistances had strong correlations with subjective perception scores (rs  = 0.75, P < 0.001 and rs  = 0.6, P < 0.001, respectively). We found a statistically significant difference between RMM-NR and CFD-NR (P = 0.003). Heat flux analysis allowed us to distinguish the more obstructed side (MOS) and the less obstructed side (LOS) in 100% of patients. CONCLUSION: This study aimed to enhance our ability to interpret CFD-calculated data in the nasal airway. It highlights and confirms that heat flux measures are very closely correlated to patient perception in cases of SD. It also helps to distinguish the more obstructed side from the less obstructed side and could contribute to further CFD studies.

Severe deviated nose treatment: importance of preserving the dorsal septal remnant.

PURPOSE: To compare the surgical outcomes of modified extracorporeal septoplasty and anterior septal reconstruction for the management of the severe deviated nose. METHODS: In a prospective cohort study, we selected 86 patients referred for septorhinoplasty to a tertiary center in May 2015-April 2017 with a primary complaint of nasal obstruction and deformity. They had moderate-to-severe septal deviation and severely deviated noses, particularly in the dorsum. Forty-three patients underwent each procedure. The cohorts were age- and sex-matched, and were operated at a similar time point. Surgical outcome was assessed and compared using anthropometric measurement of photographs, acoustic rhinometry, and The Nasal Obstruction Septoplasty Effectiveness questionnaire (including a visual analog scale). RESULTS: In all patients, MCA1 (initial minimum cross-sectional area) and MCA2 (minimum cross-sectional area after topical decongestion of the nasal mucosa), anthropometric angles (nasolabial, nasofacial and tip projection), and The Nasal Obstruction Septoplasty Effectiveness questionnaire significantly improved after surgery in both groups (p = 0001), with no significant difference in improvement between two groups. However, anthropometric angles and minimal cross-sectional area were better in anterior septal reconstruction group. CONCLUSION: Both methods are effective in patients with a severely deviated nose for correction of deviation and obstruction. Anterior septal reconstruction is the preferable method in patients with more deviation.

Long-term results after restoring nasal tip support using auricular cartilage as an intercrural columellar strut graft: the "I-Beam" technique.

BACKGROUND: The lack of nasal tip support resulting in poor protection and projection of the nose is a common cause of nasal obstruction and cosmetic impairment. Although septal cartilage is preferred for restoration of nasal tip support, there is often not enough septal cartilage available. We describe an intercrural columellar strut graft in a circumferential soft tissue pocket: the I-Beam technique. METHODOLOGY: In this cohort study over an 8-year period the clinical and biometrical long-term results after restoration of nasal tip support with an autologous auricular cartilage graft, the I-Beam technique, is evaluated. RESULTS: Out of the 72 consecutive septorhinoplasties with the I-Beam technique, we studied 66 patients in the median long-term follow-up of 89 months. In all patients a significant improvement in nasal tip projection was found. A functional improvement in nasal breathing was achieved in 86%. The overall satisfaction with the I-Beam graft was of 83%. No deterioration in smell perception was found after surgery. CONCLUSIONS: The I-Beam technique using back-to-back sutured autologous auricular cartilage is a safe and effective technique and gives long-term structural support and enhances tip projection.

[The morphological and clinical aspects of the curvature of the nasal septum]. / Morfologicheskie i klinicheskie aspekty iskrivleniia peregorodki nosa.

The curvature of the nasal septum (NS) is one of the most widespread deformations of the facial skeleton. The objective of the present study was to substantiate the principles of and develop the rationale for the surgical correction and conservative treatment of this condition based on the morphological features of various types of deflection of the nasal septum. We have undertaken the morphological analysis of the osseous and cartilaginous structures determining the type and the shape of the curvature of the nasal septum together with the clinical analysis of different morphological variants of the deflection of the nasal septum making use of the R. Mladina classification. Type I-IV vertical deflections are regarded as the acquired deformities whereas type II deviations can just as well be congenital malformations. Types V and VI deflections can be a consequence of the birth injury resulting in the displacement of the nasal structures and leading to the curvature of the nasal septum. The authors describe the defects in the anatomical structures adjoining the nasal cavity associated with various types of the deflection of the nasal septum that the surgeons should take into account when planning and performing septoplasty.

Olfactory Bulb Volume Changes in Patients With Nasal Septal Deviation.

OBJECTIVES: The olfactory bulb (OB) plays a pivotal role in the processing of olfactory information. The aim of this study was to investigate the OB volume changes and its possible associations with nasal septal deviation. STUDY DESIGN: Cross-sectional study. SETTING: Otolaryngology Department of Bozok University School of Medicine and Neurology Department of Yozgat State Hospital. SUBJECTS AND METHODS: Ninety patient's cranial magnetic resonance imaging (MRI) studies (46 males and 44 females, mean age 36 ±â€Š13.4 years; range 18-56 years) with isolated nasal septal deviations were recruited for the study. Olfactory bulb volumes in all study subjects were evaluated in T2-weighted coronal MRI images by planimetric manual contouring. RESULTS: Nasal septal deviation angles were found to range between 5° and 23.21° (mean 13.6°â€Š±â€Š3.58°). The right-sided deviations included 17 mild (<9°, Group I), 20 moderate (9°-15°, Group II), and 16 severe (15° and up, Group III) patients. The left-sided deviations included 14 mild (<9°, Group I), 13 moderate (9°-15°, Group II), and 10 severe (15° and up, Group III) subjects. Olfactory bulb volumes were calculated in both right- and left-sided deviation groups. In the patients with left-sided septal deviations of Groups I, II, and III, the left OB volumes of Groups I, II, and III were 46.49 ±â€Š3.87, 47.46 ±â€Š3.36, and 60.68 ±â€Š5.65 mm and the right OB volumes were 53.37 ±â€Š3.76, 56.47 ±â€Š4.43, and 76.69 ±â€Š6.84 mm, respectively. The statistical evaluation of the right OB volumes did not produce significant difference between Groups I and II (P = 0.73). The authors demonstrated statistically significant differences in comparison of Groups I to III and Groups II to III (P = 0.002 and P = 0.016, respectively). In the right septal deviation group for Groups I, II, and III, mean volumes of right OB volumes were 45.59 ±â€Š4.46, 48.63 ±â€Š3.78, and 61.35 ±â€Š5.84 mm, respectively, and the left OB volumes were 54.67 ±â€Š4.73, 57.65 ±â€Š4.53, and 75.84 ±â€Š7.67 mm, respectively. There was no statistically significant difference between Groups I and II (P = 0.95) left OB volumes in the right-sided deviation group, but statistically significant difference was demonstrated in Groups I to III and Groups II to III compartments (P = 0.002 and P = 0.003). CONCLUSION: In our study, while mild and moderate septal deviations lacked any significant affect on OB volumes, severe deviations were found to have significant impact on these parameter. Additionally the contralateral OB volumes in the severe septum deviation group were significantly bigger when compared to the ipsilateral OB volumes. Further multidisciplinary studies are required to evaluate the clinical significance of OB volume changes in diagnosis and follow-up of several otolaryngologic or nonotolaryngologic diseases.

Evaluation of Sleep Quality in Patients With Nasal Septal Deviation via the Pittsburgh Sleep Quality Index.

OBJECTIVE: To investigate the effect of nasal septum deviation, without obstructive sleep apnea, on sleep quality. METHODS: The present case-controlled study enrolled patients older than 16 years with nasal septum deviation who attended the Otorhinolaryngology Clinic between December 2013 and July 2014. The control group was selected from patients attending the clinic for another complaint. Sleep quality was evaluated via the Pittsburgh Sleep Quality Index, and differences between the groups were compared using the Mann-Whitney U test. RESULTS: During the study period, 55 patients with nasal septum deviation were included in the study group, and the control group consisted of 51 patients with no complaints of nasal obstruction. Compared with the control group, patients with nasal septum deviation were found to be significantly higher (P <0.05) in all parameters of Pittsburgh Sleep Quality Index. CONCLUSION: The presence of nasal septum deviation with nasal obstruction should be investigated in patients with sleep disorders. If any pathology is present, opening the nasal passages should be ensured and sleep disorders reevaluated.

Effect of Deviated Nasal Septum Type on Nasal Mucociliary Clearance, Olfactory Function, Quality of Life, and Efficiency of Nasal Surgery.

OBJECTIVE: The aim of this study was to analyze the influence of deviated nasal septum (DNS) type on nasal mucociliary clearance, quality of life (QoL), olfactory function, and efficiency of nasal surgery (septoplasty with or without inferior turbinate reduction and partial middle turbinectomy). METHODS: Fifty patients (20 females and 30 males) with septal deviation were included in the study and were divided into 6 groups according to deviation type after examination by nasal endoscopy and paranasal computed tomography. The saccharin clearance test to evaluate the nasal mucociliary clearance time, Connecticut Chemosensory Clinical Research Center smell test for olfactory function, and sinonasal outcome test-22 (SNOT-22) for patient satisfaction were applied preoperatively and postoperatively at the sixth week after surgery. RESULT: Nasal mucociliary clearance, smell, and SNOT-22 scores were measured before surgery and at the sixth week following surgery. No significant difference was found in olfactory and SNOT-22 scores for any of the DNS types (both convex and concave sides) (P > 0.05). In addition, there was no difference in the saccharin clearance time (SCT) of the concave and convex sides (P > 0.05). According to the DNS type, the mean SCT of the convex sides showed no difference, but that of the concave sides showed a difference in types 3, 4, 5, and 6. These types had a prolonged SCT (P < 0.05). Olfactory scores revealed no difference postoperatively in types 5 and 6 but were decreased significantly in types 1 to 4 (P < 0.05). There was no significant difference in the healing of both the mucociliary clearance (MCC) and olfactory functions. SNOT-22 results showed a significant decrease in type 3. CONCLUSION: All DNS types disturb the QoL regarding nasal MCC and olfaction functions. MCC values, olfactory function, and QoL scores are similar among the DNS types. Both sides of the DNS types affect the MCC scores symmetrically. Septal surgery improves olfaction function and QoL at the sixth week following surgery but disturbs nasal MCC; thus, the sixth week is too early to assess nasal MCC.

Type and severity of septal deviation are not related with the degree of subjective nasal obstruction.

BACKGROUND: Septoplasty is a frequently performed operation by otolaryngologists to relieve nasal obstruction complaints. When objective measurements tools are not available, preoperative decision-making is based on careful clinical examination. Our aim was to evaluate the relationship between type and severity of septal deviation and patient-reported nasal obstruction. METHODOLOGY: 196 Patients of a general otolaryngology population were included. Patients indicated subjective nasal obstruction experienced during the past 1 month on a Visual Analog Scale (VAS). Patients underwent clinical examination to evaluate type and severity of septal deviation. We compared clinical examination findings with patients VAS. RESULTS: We did not find a statistical difference of VAS score between the different types and severities of septal deviation. In 33.9% of the cases without septal deviation, there was a corresponding VAS score of 0. In 26,8% of the cases with septal deviation, there was no complaint of nasal obstruction (VAS = 0). In 7,4% of the cases, there was moderate to severe nasal obstruction complaint (VAS over 4) though no septal deviation was found. CONCLUSIONS: These results demonstrate that patient-reported nasal obstruction varies greatly among patients with similar type of deviation and similar degree of deviation. Classification of septal deviation into type and severity cannot predict the degree of subjective nasal obstruction. Therefore, the decision to proceed to septoplasty has to be thoughtful, with as much as information, based on the combination of patients history, clinical examination, surgeons experience and cautious interpretation of objective measurement tools.

Reconstruction of nasal tip support in primary, open approach septorhinoplasty : A retrospective analysis between the tongue-in-groove technique and the columellar strut.

The reconstruction of the nasal tip support is one of the most essential issues in septorhinoplasty. A comparison of the results after using the tongue-in-groove technique and the columellar strut technique was the target of this study. Thirty-three patients who underwent a primary, open approach septorhinoplasty using the above-mentioned techniques were retrospectively analyzed. The gain in tip rotation postoperatively, the sensitivity and the rigidity of the nasal tip and the aesthetic outcome after surgery were examined and evaluated. Both techniques led to an increase in nasal tip rotation postoperatively. The gain in rotation was higher in patients, treated with the tongue-in-groove technique (p = 0.0052). The sensitivity of the tip region in the tongue-in-groove group of patients was significantly lower than that in the columellar strut group of patients (p = 0.0424). Both techniques led to high percentages of tip rigidity after surgery with satisfactory aesthetic results though. The tongue-in-groove technique and the columellar strut technique are both reliable techniques for reconstructing the nasal tip support and correcting a droopy tip. Although the tongue-in-groove technique might result in a more significant increase in tip rotation, it leads to less sensitivity in the tip region.

Evaluation of nasal mucociliary transport rate according to nasal septum deviation type.

BACKGROUND: Nasal septum deviation (NSD) may affect mucociliary activity (MCA) to varying degrees, depending upon the severity of the deviation. We used rhinoscintigraphy to determine the impact of the various NSD types on MCA. METHODS: A recent classification describing 6 different forms of NSD was used to standardize the study. Forty-eight subjects were enrolled. Eight patients for each form of NSD were accrued for further study. Rhinoscintigraphy was performed using technetium 99m macroaggregated albumin ((99m) Tc-MAA) before and 3 months after surgery. Nasal mucociliary transport rate (NMTR), the half-time of (99m) Tc-MAA activity, and clearance rate over a 20-minute period were compared between groups. RESULTS: Preoperative NMTR and clearance rates were significantly lower and half-time was significantly longer in types 4 and 6 than in the other groups. Although the postoperative NMTR and clearance rates increased compared with preoperative values in all groups, the increase was significant only in types 2, 4, and 6. The postoperative half-time increased significantly compared with the preoperative values in types 2, 4, and 6. The postoperative rhinoscintigraphy evaluation revealed no significant differences among groups in NMTR, half-time, or clearance rate. CONCLUSION: NSD types 4 and 6 had lower preoperative NMTR and clearance rates and a longer half-time compared with the other groups. However, the postoperative values of these parameters were not significantly different among groups. Our results indicate that NSD types 4 and 6 had the greatest impact on MCA, suggesting that these patients may receive the maximum benefit from septoplasty.

Are temporomandibular disorders associated with habitual sleeping body posture or nasal septal deviation?

Numerous factors can be considered for the etiology of temporomandibular disorders (TMD). The aim of the present study was to investigate whether the presence of both nasal septal deviation (NSD) and habitual prone sleeping posture (HPSP) predisposes TMD. We evaluated 200 subjects in 4 groups. Group I (NSD-, HPSP-/control group), Group II (NSD+, HPSP-), Group III (NSD-, HPSP+), Group IV (NSD+, HPSP+). All patients were examined according to the research diagnostic criteria to determine the presence of TMD. Group IV had the highest value for TMD incidence (44 %). Thus, we found that the presence of both NSD and HPSP parameters increased TMD incidence in Group IV compared to the control group (p = 0.000). Additionally, Group IV showed significantly higher values than Group II (p = 0.012) and Group III (p = 0.039). For Group III (NSD-, HPSP+), TMD was determined higher compared to the control group (p = 0.009). A statistically higher value of presence of TMD was determined in Group II (NSD+, HPSP-) than control group (p = 0.029). The incidence of TMD was significantly higher in women than men (p = 0.020). We concluded that one having an unilateral obstructive nasal septal deviation in addition to a habit of sleeping in prone position must be alert for potential TMD.

A novel method for reconstruction of severe caudal nasal septal deviation: Marionette septoplasty.

We conducted a retrospective study to compare open and endonasal (closed) approaches to extracorporeal reconstruction of severe caudal septal deviations. From January 1, 2010, through December 31, 2013, 78 patients with severe caudal septal deviation underwent corrective surgery at our hospital. Of this group, 33 patients (mean age: 32 yr) underwent extracorporeal septoplasty via an open approach, and 45 patients (mean age: 35 yr) underwent treatment with a new procedure that we developed: subtotal extracorporeal septoplasty through a closed approach, which we call "marionette septoplasty." In addition to demographic data, we compiled information on surgical time, the duration of postoperative edema, the degree of postoperative pain, and differences between pre- and postoperative nasal function and tip support in both groups. We found that our marionette septoplasty procedure required significantly less surgical time and resulted in a significantly shorter duration of postoperative edema than did open septoplasty, while there was no statistically significant difference between the two procedures in the degree of pain. Following surgery, nasal function in both groups improved significantly, without any significant difference between the two. Finally, we documented improved tip support in all 78 patients. Our results show that marionette septoplasty produces the same functional results as does open septoplasty while requiring less surgical time and shortening the healing period.