The Application and Efficacy of Hyaluronic Acid Fillers for Chin Enhancement and Retrusion Correction: A Systematic Review of Patient-Reported Outcomes

A frequent facial abnormality called chin retrusion, also known as retrognathia, can be detrimental to a person's self-esteem and overall face aesthetics. Hyaluronic acid (HA) injections are one non-surgical approach to this problem that may provide individuals seeking chin augmentation with a relatively less invasive and potentially more affordable alternative. The present literature does not provide enough in-depth systematic reviews of the use of HA in chin augmentation. By completing a complete examination of the information that is currently available, this study intends to fill this knowledge gap, supporting physicians and researchers in better comprehending the efficacy and implications of HA in chin augmentation. The safety and success of any esthetic procedure should be made based on the results reported by the patients, including satisfaction and quality of life. Patients need to receive comprehensive surgical instructions from a medical professional to optimize the results of the HA injections for chin enhancement surgery. Regardless of the reported safety of using HA injections, some unwanted side effects have also been recorded. Indeed, healthcare professionals can make more informed decisions and give a patient comprehensive information about the procedure's risks and benefits to the patients. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. EMBASE, OVID, and Google Scholar databases were searched up to June 2023. We concentrated on adult patients treated with HA for chin enhancement, and our research was limited to studies conducted in English. A total of 2,738 patients from 24 articles were studied, with 2,259 receiving HA injections for chin augmentation. When applicable, aesthetic outcomes were assessed using scales such as the Global Aesthetic Improvement Scale (GAIS)/FACE-Q and the Galderma Chin Retrusion Scale. Patient satisfaction increased noticeably. Among the studies, some reported complications following HA injection. While three studies found no significant negative effects, one highlighted a major necrotic complication. HA has proven to be an effective and safe alternative to chin augmentation surgery, with the majority of patients showing high satisfaction rates. However, large-scale randomized controlled trials are needed to obtain meaningful results, which will contribute to the further development of non-surgical cosmetic procedures. These studies may facilitate further innovation and refinement of these techniques and potentially expand the application of HA fillers in facial aesthetics.


Introduction And Background
A significant viewpoint that worries many people is that of facial cosmetic operations [1].The chin aesthetics procedure is one of the crucial facial features because the lower half of the face has an alluring appearance [2].A variety of factors, including genetics, skeletal deformities, and dental issues can cause chin retractions.Chin retraction is a disorder that affects a person's appearance and functionality.The course of treatment, which may involve a chin implant, an orthodontic procedure, orthognathic surgery, and the use of dermal fillers containing hyaluronic acid (HA), depends on how severe the condition is.Because it gives us the appearance of beauty and youth, a well-contoured jawline with a distinct contour from the mandibular angle to the chin is desired in both men and women.Chin retrusion is an undesirable facial feature that might cause an unpleasant facial look.HA is a natural element in the body that helps preserve the hydration and flexibility of the skin.Recently, using HA fillers has grown in popularity as a proficient way to repair the chin and fix retrusion [3].HA fillers, when injected into the chin region, can enhance volume while also enhancing the chin's contour and symmetry, giving the face a more harmonious and attractive appearance.The effectiveness of HA fillers for chin enhancement and retrusion correction has not been the subject of a comprehensive review.The goal of this study was to present a thorough analysis of the effectiveness and significance of employing HA for chin augmentation.

Review Materials and methods
The Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42023452008) was used to register this systematic review, and it was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [4].A comprehensive electronic search of the Embase, OVID, and Google Scholar databases was conducted for studies published between the earliest available date and June 2023.The search strategy following the traditional PICOS method of searching electronic databases was developed independently by one of the authors (Mustafa Al-Khafaji), and it was approved by the study team members prior to implementation.Using the medical subject heading (MeSH), a combination of the following keywords was used ("Hyaluronic Acid Fillers" or "Hyaluronic Acid" or "Dermal Fillers" or "Facial Fillers") and ("Chin Enhancement" or "Chin Augmentation") and ("Retrusion Correction" or "Retruded Chin Correction").

Eligibility Criteria
Chin enhancement and retrusion correction studies for adult patients that used only HA fillers and were published in the English language were included.Studies were required to report patient outcomes, case series, or original articles, including randomized controlled trials (RCTs), prospective cohort studies, retrospective cohort studies, and non-randomized non-comparative studies.The primary outcome of interest is patient-reported outcomes, which include satisfaction, aesthetic improvement, and adverse events related to HA filler treatment.Studies that did not report patient-reported outcomes were excluded.Exclusion criteria included studies that investigated other types of fillers or surgical interventions, studies that did not stratify results based on aesthetic procedure, studies including patients below the age of 18, improper methods (reported a meta-analysis/systematic review, economic analysis, animal study, cadaver study, narrative review, or editorial), and studies that reported no outcomes of interest.

Selection of Articles and Data Extraction
Six reviewers independently assessed the titles and abstracts obtained from the search strategy using "Rayyan" software (Rayyan Systems Inc., Cambridge, MA), following the study's eligibility requirements [5].Following that, the full texts of the selected abstracts were individually evaluated by all authors to determine the final eligibility.When there was disagreement, the reviewers worked together to reach a consensus.This process ensured that only relevant and appropriate studies were included in the final analysis of this research, improving the accuracy and reliability of the study selection.The first author, title, year of publication, journal, study design, country, number of patients, main complaint, treatment sites, age range, mean age, total of HA filler injected, total number of syringes used, brand of filler, touch up injections, follow-up period, complications, patient improvement rate (GAIS) for investigators and subjects, and overall conclusions were extracted from each study.Risk-of-bias assessment tools were used to independently assess the quality of the included studies.Depending on the study's design, various bias tools were used.The revised Cochrane risk-of-bias tool was used for randomized trials, the MINORS tool was used to assess the quality of non-randomized studies or prospective cohort studies, and the Newcastle Ottawa Scale was used for retrospective cohort studies [6,7].

Evaluation of the Statistical Data
In spite of our attempt at a rudimentary descriptive statistical analysis, the heterogeneity of the included articles and the absence of data in a format conducive to meta-analysis made it unfeasible to conduct a meta-analysis.

Overview of the Literature
At the beginning of the study, the authors found 382 publications, 344 from Ovid (which included Embase and research papers from the Cochrane Library), and 38 from Google Scholar.After duplicate papers were discarded, the titles and abstracts of 214 different research were examined.After reviewing the entire texts of 68 publications, we found that 24 satisfied the requirements for inclusion or exclusion.Several factors led to the exclusion of a significant number of articles, including the absence of HA information in two, the use of non-HA materials such as botulinum toxin type A and poly-l-lactic acid (PLLA), alongside HA in 15, the absence of specific patient-reported outcomes in 16, the focus on HA injection complications in three, and the failure of the remaining eight articles to specifically address chin enhancement.Between the beginning of time and June 2023, all of the studies that made up this review were published.
The summary of studies (Table 1) includes chin enhancement and chin retrusion correction using HA.Publication for American

Authors
VYC-20L  We looked into four randomized clinical trials, four non-randomized non-comparative studies, six prospective cohort studies, and 10 retrospective studies.There were no case reports or case series that were included.A total of five studies were carried out in Italy, three in the United States, two in the United Kingdom, one in Canada, two in France, two in China, one in Germany, one in Spain, one in Korea, one in Taiwan, one in Turkey, one in both nations of Japan and China, one in Brazil, and two throughout Europe (Germany, France, and the Netherlands), as shown in Figure 1.A synopsis of the PRISMA method is provided for our systematic review in Figure 2.

FIGURE 1: The global geographical representation of research papers regarding chin HA augmentation/retrusion correction
The retrieved studies are depicted in blue color.Throughout the entire study, an overall of 2,738 patients have been assessed.This includes 2,259 patients who received HA filler for chin augmentation or treatment of chin retrusion.An explanation of the clinical features of the studies incorporated is available in Table 2.The patients ranged in age from 18 to 80 years old, having a mean age of 42.37.In terms of gender, there were 283 males and 1,976 females (87.5%).The average (initial treatment mean total volume of HA filler injected was 2 mL/patient) ranged between 0.30 and 3.90 mL/patient.In terms of procedural setting, 11 studies were multi-center, four studies were conducted in a private clinic, seven studies took place in the department of plastic surgery in different hospitals, one study took place in a university hospital, and one study was conducted in a research institute.The duration of product efficacy was estimated to range from one to more than 18 months, with a mean of 13 months (12.84).In this review, only six studies reported on the technique of administering (HA).These included the tunneling technique (n=4) and the fanning injection technique (n=2).This review covered any research that utilized HA for chin augmentation and chin retrusion.There are eight research papers that used Restylane, six used Juvéderm Volux, five used Juvéderm Voluma, one used ART FILLER, one study used multiple fillers (such as Restylane, Biohyalux, Neuramis, Yvoire, Juvéderm), and three failed to indicate the kind of HA utilized.The amount of HA provided differed among the research studies examined.Fortunately, 10 studies reported the initially administered volume of HA filler injected, while nine reported the touch-up volumes injected.Meanwhile, 23 of the studies indicated the total amount of HA filler injected mL/patient (initial volume injected + touch-up volume administered).The quantities of injected HA are outlined in Table 2.The same amount for each product was injected to the subjects

Authors
The amount of product injected varied according to the deficit to be corrected, but a maximum of 1.2 ml was authorized to be injected for the midface, 1.2 ml for the temples, 1.2 ml for the jawline, and 1.0 ml for the chin via one single supra-periosteal bolus injection with a 27G1/2 (13 mm) TSK® needle or a 25G/55 mm cannula (SoftFil®).Towards the end of the procedure, a massage is applied.
Voluma gently spreads through every single one of the tunnels, leading to in a harmonious, natural-looking appearance.The aesthetic effects of HA fillers were collected by a particular survey utilizing several scales and instruments, such as the global aesthetic improvement scale (GAIS) / FACE-Q questions or Galderma chin retrusion scale if present for SUBJECTS.Seventeen research investigations found a statistically significant improvement and enhancement in the scale utilised and the overall satisfaction among patients.The overall patient satisfaction using the scales is outlined in Table 3.In 40 patients only 20 had complications; soft-tissue edema (12), hematoma (6)  Seventeen of the studies encountered complications resulting from HA chin injections.Three studies found no significant treatment-related adverse events, while a single study reported one major complication of necrosis using Juvéderm.In regard to minor complications, 17 studies reported cases of bruising and hematoma, 14 studies experienced swelling and edema, 11 had pain and tenderness at the injection site, eight studies reported erythema and and redness, and five reported nodules with lumps/bumps that were resolved with hyaluronidase.Three studies reported scars and asymmetry, two studies reported pruritus and itching, two studies reported hypersensitivity, one experienced local mobility of the implant, one study experienced overcorrection, and one reported vascular occlusion.The reported duration of follow-up in every study varied from two days to a period of 24 months.

Quality Assessment and Risk of Bias
Two members of the review team (WA and ZA) independently assessed the risk of bias in each study, using the Cochrane Collaboration's tool for risk of bias assessment in RCTs, three of the included RCTs were considered low risk of bias, and only one was considered high risk (Table 4).Four of the non-randomized non-comparative studies were assessed by MINORS tools, and the total score ranged from nine to 15, with a mean score of 11.9 (Table 5).The Newcastle Ottawa Scale was used to assess bias in 16 of the retrospective, along with prospective cohort research studies, and scored seven out of nine, indicating a high level of quality (Table 6).

Quantitative Data Analysis
Since there were differences in techniques, treatments, inadequate extracted data, and outcomes assessed, quantitative meta-analyses were not possible.

Discussion
The primary objective of our systematic review was to gather application and safety data for HA fillers in patients seeking to correct volume deficit and retrusion in the chin.The findings of our review suggest that HA injectable fillers have an acceptable safety profile and are effective for restoring and creating facial volume in contouring the chin and projecting and sculpting it.In addition, the repeated treatment of several facial indications showed a satisfactory safety profile.The chin is a crucial facial feature for overall attractiveness, impacting facial symmetry and balance [32,33].A rather frequent disorder, chin retraction, can be brought on by heredity, bone anomalies, habitual posture, and dental issues.A common facial abnormality called chin retrusion can make the face appear imbalanced and less attractive [31].In recent years, using HA fillers to augment the chin and correct retrusion has been popular and effective [34].A naturally occurring substance in the body called HA helps keep the skin supple and hydrated [35].When injected there, HA fillers can add volume and improve the symmetry and contour of the chin, giving the face a more beautiful and harmonious appearance.Through reviewing the included studies, most of the patients in all studies' satisfaction rates were exceptionally high, as well as experienced minor and tolerated complications compared to the perfect results of HA filler injection.Reported complications included the following: bruising and hematoma, swelling and edema, erythema and redness, pain, and tenderness in the injected area.All reported complications did not affect the process of injection.Necrosis was reported in one study where an individual used Juvéderm [14].Contrary to alternative surgical treatments for chin augmentation, the low rate of problems demonstrates that HA injectable fillers are an excellent choice for assuring patient happiness and comfort.These results emphasize the need to use specialized methods to increase the security and effectiveness of HA filler injections.According to GAIS, patients were significantly improved in 13 of the studies under consideration.Several restrictions should be taken into account when evaluating the results of this systematic review.There is a chance of linguistic bias because the inclusion criteria only apply to papers written in English.The exclusion of other papers published in any other language may have compromised the thoroughness of this evaluation.

Conclusions
In conclusion, research findings suggest that HA injections could serve as a suitable and effective treatment to enhance the overall appearance of an individual's chin.Through this endeavor of performing a systematic review, we intend to demonstrate through our analysis greater patient satisfaction, long-term aesthetic effects, and product efficacy for up to 18 months post-treatment.Apart from one serious event that was not directly associated with HA injection administration, the problems reported seemed to be mostly minor.
Injectable chin HA offers a special therapeutic and cosmetic potential for treating patients unable to have surgery, thus providing a viable and beneficial option that has the potential to be used to address a range of chin aesthetic and functional challenges as part of the plastic surgeon's reconstructive and aesthetic choice.HA is clearly influential, and we consider it a safe and great alternative to surgical treatments, with the degree of retrusion determining the treatment option.Larger research, however, is required to get more definitive findings.

FIGURE 2 :
FIGURE 2: The summary concerning the research studies considered for the purpose of this systematic review according to PRISMA per normal practice and the CAF was completed posttreatment.Key data collected from the injectors via the CAF comprised type of anesthesia used, site of injection(s) and volume injected, ease of injection, ease of sculpting/massaging, overall cosmetic effect (including smoothness), aesthetic effect versus previous Restylane and preference, probability of recommending Voluma, and details of any adverse events.inserted within both of the lines connecting the prejowl sulcus and the oral commissures, into the chin and the region inferior to the lower part of the lip.The chin-filling injection technique used by the authors, which involves six to eight injection sites, is an effective technique with a low rate of complications and high patient satisfaction.The pogonion and the menton.If necessary, an extra entry point was set at the midpoint between the pogonion and menton.A 27G was used for midline chin injections, inserted perpendicular to the skin at each injection site until it reached the periosteum.Although the midline of the chin away from the lower lip area is a vascularized area, it is recommended to inject HA slowly with low pressure after aspiration.The mental ligament was used to achieve local lifting.A blunt-tipped 23G cannula was inserted via this entry point to modify the lower mandibular margin.For male patients, the lateral mental (LM) point (the midpoint of the line between the ML and the gnathion) could be added for chin injection to improve the jaw width

First, they started
by removing make-up, followed by thoroughly washing off their face.Appliance on topical anaesthetic cream.At the time of the injection, those receiving treatment were in a semirecumbent position.An antiseptic solution for sterilization purposes was used.The chin and surrounding areas were sterilised on three separate occasions using ethanol.A sharp needle was used to inject HA into the subperiosteal plane to increase bone volume and improve chin projection and width.A cannula was used to perform subcutaneous plane fanning and threading injections to smooth the surrounding skin, soothe the pre-jowl sulcus, and decrease the labio-mandibular groove on both sides of the face.Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.usinga topical antiseptic with 2% phenoloxyethanol and 0.1% octenidine hydrochloride.The next step is to find the menton, the chin's most inferior projecting point.A 23G punching needle is inserted through the skin and SC tissues perpendicularly and then removed.This single midline point of entry was used to insert a 25G 50 mm injection cannula, and 20 mg/mL cross-linked HA with 0.3% Lidocaine was added to the suggested augmentation area.Cannula from a single entry point in the middle.A multilayered, retrograde, lateral-to-medial form of tunnelling technique was used to augment the chin both supra-periostally and subcutaneously.patient was positioned upright in the Frankfurt plane before marking to determine the areas to be treated.(Juvederm Voluma) HA was injected above the periosteum and the deep dermal plane using a 25-27 gauge needle.The planned amount of injected filler was 1 mL.
choice of the injection technique, injection depth (into the supraperiostic zone or subcutis), and injected volume were at the discretion of the investigator.amount of filler used varied depending on the size of the face and the deficit.HA filler was injected into the supraperiosteal plane.Aspiration was done prior to injection.for the pre-auricular area, mandibular body, lower prejowl, lower anterior chin, labiomental angle, and lateral chin & a 27 Gauge 18 months The standardised MD CodesTM served as the basis for injection points which employed the Volux®.Utilising a linear approach, 0. 5-1 mL of VYC-25 for each side was injected SC into the lower pre-jowl and lower anterior chin in the jaw line.Utilising a fanning technique, labiomental angle was injected SC with 0. 5-1 mL per side.The chin's apex was injected in the middle line, SC, or supraperiosteally with 0. 2-0.4 mL on each side.0.2-0.4mL per side were injected into the anterior chin in the supraperiosteal plane, being careful not to get too lateral because of the mental artery.0.2-0.4mL was utilised to inject the anterior NA 3 centers Italy 2023 Al-Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.chin/pogonionSC in the middle line, 0. 2-0.4 mL was utilised to inject the lateral lower chin supraperiostally, and 0. 1-0.5 mL of VYC-25 per side was utilised to inject the lateral chin in the subcutaneous plane using a fanning technique.Due to the high viscosity of VYC-25, the injection regions were lightly massaged using fusidic acid cream for disinfection and to avoid the formation of pseudo-nodules. of horizontal and vertical lines was used to systematize the process of treatment planning and performance.Lines were traced onto individual patients' faces with skin pencils to allow precise recording of defects and to generate reproducible injection points that could be precisely quantified.specific injection points were designated for female patients and male patients.Other points were used to further redefine the jawline.Using Equivalent MD Codes standardized approach to of the chin and jaw were focused on the pogonion, submental crease, mentum, pre-jowl sulci, jawline, and/or and/or subcutaneous injections into the pogonion, menton, and pre-jowl sulci, cannulas were permitted for supra periosteal and/or subcutaneous injections in the menton and prejowl sulci.An appropriate injection volume for the chin and chin area.anaesthesia, dermal incision.Transdermal insertion of the blunt-tipped cannula for the administration of Restylane sSubQ into SC or Supra periosteal tissue.massage the treatment area to conform to the contour of the surrounding tissue.if necessary.NA 4 centers in Canada Canada 2023 Al-Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.mg/mLsmooth and cohesive hyaluronic acid (HA) filler was injected using a 21G cannula to minimize the risk of embolization.The cannula was inserted just above the periosteum, and the filler was slowly injected while withdrawing the cannula through the muscle layer to the subcutaneous plane.The volume of the injection was determined by the patient's condition.After the procedure, a cold compress was applied to reduce swelling and soreness, and dressings were generally not required.transdermal insertion of a blunt-tipped 16G cannula for administration of HA into SC or supra-periosteal tissue.The NASHA gel was injected in small aliquots throughout the area requiring augmentation by manipulating the cannula into a different tract after each injection, using a tunnelling technique.prevent harming deep facial elements, the piston inside the Voluma syringe was continuously pushed throughout the entire procedure, resulting in the formation of multiple tunnels.The little viscous HA bolus is thick and always comes before the needle tip, acting just like a cushion that helps dissect the tissue prior to the needle.The most effective way to administer Voluma treatment is to cross the various tunnels across various planes in order for the product to spread into and under the fat pads.Any large boluses should be avoided.
injection of a 27G needle was used for the administration of Volux into the chin.A maximum volume of 4.0 mL was allowed for the initial and touch-up treatments combined, and up to 4.0 mL could be injected for repeat treatment.No more than 2.into any single treatment area.Treatment areas included the pogonion, mentum, pre-jowl sulci (left and right), and sublabial (mental) crease.

1
lasted up to 48 weeks, indicating the long-lasting correction of chin retraction in most subjects.In comparison to the notreatment control group (35.1) on the 12th week, the FACE-Q Satisfaction with Chin scale, which The majority of adverse events were mild, with the exception of one moderate event that involved implant-site pain, and their median duration was 4 days.Implant-site bruising (2%), implant-site swelling (2%), and pain (5% of subjects) were the most frequent events.Two instances of implant-site nodules were observed: one that appeared 53 days after treatment and was described as "irregular resorption for the product leading to a 6-mm nodule."It cleared up after 74 days with hyaluronidase treatment, and the other that appeared on the day of treatment and was called a "filler nodule on the chin" resolved following 112 days without any Conducted over 48 weeks 2023 Al-Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.6).At baseline, the mean scores for both groups were similar: 34.6 for the control group and 37.4 for Restylane Defyne.Between week 12 and baseline, there was a statistically significant treatment difference.further action.The study did not find any significant adverse events related to treatment.Patients reported events during the four weeks following injection; these were deemed tolerable and resolved for the most part in 14 days.Following initial treatment, the most frequently reported symptoms in the diaries had been tenderness (90%), discomfort and pain (), as well as asymmetry in eight individuals (2.5%).Additional risks that include infection, nodule, necrosis, or a witch's chin were not present.Every individual felt satisfied with the outcome of the HA injections.GAIS, nine patients (18%) showed improvement, 28 patients (56%) seemed much improved, and 13 patients (26%) seemed very much improved.Throughout the surgical procedure, none of the patients experienced any discomfort.Slightly mild to moderate erythema and swelling were reported by 48 out of 50 individuals (96%) and went away in a few days.The procedure caused ecchymosis in four (8%) of the patients.Fortunately, skin necrosis had not affected any of the patients.GAIS score: Day GAIS score: Day 21 post-operation: 92 Side effects were associated with patients either injected with Juvéderm® Voluma or ART FILLER® across this study; 2023 Al-Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.ofsubjects with improvement GACS: The best success was observed on the chin with 73% of subjects for whom a decrease of one grade in the initial (GACS) The Global Aesthetic Clinical Score was still present at Day 540 (18 months).Erythema (24) with both fillers, Ecchymosis (4) with both fillers, Hematoma (10) with both fillers, -operation: 63% of patients Very much Improved.33.3% of patients Much improved.3.7% of patients Improved.18 months postoperation: 7.4% of patients Very much Improved.55.6% of patients Much improved.25.9% of patients Improved.Only 1 subject (1.6%) experienced 6 bruises limited to the injection site at injections and resolved without treatment before the next visit 3 weeks later.There were no severe AE or AEs leading to study discontinuation.Throughout the next 3 weeks post-injections; 50% of subjects experienced swelling, and 25% experienced bruising.no erythema or pruritus was experienced.The pain worst score was jawline raised substantially throughout all FACE-Q questions as well as time points.Two patients (6.7%) experienced device-related TRAEs, two patients (6.7%) experienced six severe complications unrelated to the device or procedure, and 16 patients (53.3%) experienced 27 treatment-related adverse events (TRAEs).Tenderness to touch (21 patients; 70%), firmness (18 patients; 60%), and lumps/bumps (15 patients; 50%) were the most commonly reported injectionrelated events.Of the three subjects who reported serious injection-related events, two of them had bruises, and one of them had redness.The majority of injection-related side effects subsided after seven days, but two individuals had lumps or bumps that persisted for more than thirty days.At the final 12-month visit, only one patient reported being bothered by the scars, and only four patients reported being bothered by parts of their face that were not smooth.Khafaji et al.Cureus 15(11): e48807.DOI 10.7759/cureus.thescores found before and 90 days after the treatment, we can observe that posttreatment scores were significantly lower than pre-treatment scores (P < 0.05).This indicated improvements in esthetic and psychologic metrics perceived by the patient The overall rate of complications was 1.4%.Asymmetry (0.3%), Bruising (6%), and Mild pain (12%) disappeared in 1.5-2.5 hours.No cases of skin necrosis or skin loss were observed.None of our patients reported distress.
. Representativeness of the exposure cohort?Q2.Selection of the non-exposure cohort?Q3.Ascertainment of exposure?Q4.Demonstration that outcome of interest was not present at the start of the study?Comparability: Q5.Comparability of cohort on the basis of the design or analysis?Outcome: Q6.Assessment of outcome?Q7.Was follow-up long enough for outcomes to occur?Q8.Adequacy of follow-up of cohorts?

TABLE 2 : Quantities injected for each study
[9]oughout all the studies, the cannula sizes utilized for the study participants varied from 16 gauge to 27 gauge, 13 research studies used 27 gauge needles as their preferred option for administering HA.A total of 19 studies injected HA into the intended plane subcutaneously and/or supraperiostally.A total of 0.30-3.90mL of HA was injected per patient for optimum chin augmentation/retrusion correction, with a mean of 2 mL/patient.In one of studies, Marcus et al. injected 2.61 mL on each occasion until ideal outcomes for the whole chin were attained, and upon the four-week touch-up, he injected 1.35 mL[9].Moreover, 12 studies used lidocaine as a local anesthetic during HA chin augmentation, and 11 studies included in this review used postoperative antibiotics, anti-inflammatories, and hyaluronidase (if indicated).