Odontogenic keratocyst: Review of 256 cases for recurrence and clinicopathologic parameters

Treatment of benign maxillomandibular osteolytic lesions larger than 4 cm: A systematic review

OBJECTIVE

This systematic review aimed to assess the different treatments of benign maxillo-mandibular radiolucent bone lesions over 4 cm to propose a management algorithm.

STUDY DESIGN

A literature search was conducted using MEDLINE/PubMed, Scopus, Google Scholar, Virtual Health Library databases, and gray literature. Randomized or non-randomized clinical trials and case series with 10 or more patients with a minimum follow up of 1 year, published in French or English until August 2023, were included. The risk of bias was assessed for all papers included.

RESULTS

Of 1433 records identified, 22 were included in this review, reporting data from 1364 lesions. Ameloblastoma was the most common lesion (51.22%) and mandible was the most common site (81.21%). Initial conservative treatment was prevalent (71.04%). Recurrence was higher after conservative (13.8%) than after radical treatments (6.5%). Multilocularity, cortical perforation, dental element preservation were linked to a higher recurrence risk.

CONCLUSION

This study has shown importance of understanding specific characteristics and recurrence risk in benign maxillomandibular osteolytic lesions. Multidisciplinary team approval, personalized approach based on lesion type and patient are crucial. The presence of at least one risk factor could lead to therapeutic decision. Despite limitations, the study informed lesion management and provided precise recommendations.

A review of oral pathology in orthodontics. Part 2: Pathology of the jaw bones

For many patients, their first full jaw imagining will be requested and reported by an orthodontist. This may lead to the discovery of unexpected pathology in the jaws. In this review article, we discuss the clinical and radiological appearance as well as the pathologic features and treatment of the more common entities of the jaws. In addition, we will discuss the less common lesions which carry important consequences for the patient. Through the identification of these lesions, appropriate referral and management can be pursued.

Odontogenic keratocysts: A retrospective histopathological study

Introduction

Odontogenic keratocyst (OKC) is an aggressive recurrent cyst with intriguing features. Various factors such as the surgical procedure are involved, and certain histological features contribute to its recurrence. We assessed the clinical, radiographic, and histopathological data of OKCs to better comprehend the true nature of this cyst.

Material and Methods

A total of 58 lesions including four cases in association with nevoid basal cell carcinoma syndrome (NBCCS) were assessed. Radiographic features and histopathological features within the epithelium and capsule were assessed.

Results

72% of cases were seen in males and 28% in females. 43% of cases were seen in the mandibular ramus, and 65% exhibited unilocular radiolucency. 95% showed true parakeratinization. Cuboidal basal cell morphology was seen in 41.3% of cases and reversal of polarity in 60%. Basal budding, rete pegs, and mitosis were also observed within the epithelium. The epithelium showed separation at the subbasal level and suprabasal levels in 55 (94.9%) cases.

Conclusion

Features such as basal cell budding, suprabasal mitotic activity, suprabasal split, localized inflammation, subepithelial hyalinization, and satellite cysts were commonly associated with recurrent cysts. Many newer genetic and molecular hypotheses have generated path-breaking contributions to the understanding of the biology of OKC. With the guidance and help of such factors, improved post-surgery results can be anticipated.

Assessing Conservative Treatment Options for Odontogenic Keratocyst in a 12-Year-Old Patient, with 1-Year Follow-up

The odontogenic keratocyst (OKC) is a frequently developing odontogenic cyst that accounts for 10%-14% of all jaw cysts. Due to the high recurrence rate, aggressive therapeutic techniques such as jaw resection and marsupialization are indicated. Following a conservative marsupialization procedure in which Carnoy's solution and an iodoform packing were used, the clinical, radiological, and histological evaluation of OKC in a 12-year-old female patient revealed no evidence of recurrence over the subsequent year of follow-up.

Sociodemographic and clinical characterization of cases of 1,103 non-syndromic and 66 syndromic odontogenic keratocyst: a Brazilian multicenter study

OBJECTIVES

This multicenter study aimed to evaluate cases of non-syndrome and syndromic odontogenic keratocyst, as well as cases of recurrence within these two groups.

METHODS

This descriptive, analytical, retrospective cross-sectional study evaluated the sex, age and presence of multiple lesions in 1,169 individuals seen at 10 Brazilian oral and maxillofacial pathology centers. Of these, 1,341 odontogenic keratocysts were analyzed regarding clinical diagnosis, size, site, imaging appearance, signs and symptoms, type of biopsy, treatment, and recurrence.

RESULTS

There was a similar distribution by sex. The median age of non-syndromic and syndromic patients was 32 and 17.5 years, respectively. The posterior mandible was the site most affected by small and large lesions in both groups and in recurrent cases. Unilocular lesions were more frequent, also in recurrent cases. Mainly small lesions showed this imaging appearance. Signs and symptoms were absent in most cases. Conservative treatment was the most frequent modality in all age groups, regardless of the patient's condition and recurrence. Recurrences were uncommon.

CONCLUSION

This study showed a higher frequency of non-syndromic keratocysts in the population. Clinicopathological features related to the involvement of multiple sites, age, and recurrence may differ between syndromic and non-syndromic cases. Furthermore, we found an association between lesion size and some clinical features and between the time interval to recurrence and the syndromic spectrum.

CLINICAL RELEVANCE

To contribute to a better understanding of the distribution and association between clinical, imaging, and sociodemographic characteristics in each spectrum of the lesion.

Odontogenic Keratocysts: Presentation and Surgical Outcome in a Sample of Sudanese Patients

Background

Odontogenic keratocyst (OKC) is a benign intraosseous lesion relatively frequent in the oral cavity. It has a locally aggressive behavior and exhibits a high propensity to recur after treatment. The present study aimed to investigate the clinicoradiographic presentations and outcomes of surgical treatment of OKC at Khartoum Teaching Dental Hospital. Material and Methods. Fifty-five cases of OKC files at the Department of Oral and Maxillofacial Surgery in Khartoum Teaching Hospital between 2012 and 2022 were reviewed and studied using a descriptive prospective cross-sectional study. Data were analyzed using Statistical Package for the Social Sciences (SPSS) version 27.

Results

Out of 55 cases studied, the mean age at the time of diagnosis was 30 ± 17.6 years; of them, 28 (50.9%) were males and 27 (49.1%) were females. The most common clinical manifestation was swelling (34.9%), followed by pain (28.0%). Sixty-five percent of the OKCs were located in the posterior mandible, and multilocular radiolucency (73.6%) was the most prevalent radiological finding. Enucleation with Carnoy's solution (CS) (55.2%) was the most common surgical modality that was used in more than half the patients, and only six patients had a recurrence. Marsupialization and segmental resection had no recurrence, while marginal resection and curettage had the highest recurrence rate of 20%. Patients with consanguineous parents had a higher recurrence rate (15%) compared with patients who had nonconsanguineous parents (8.6%). None of the patients died or had a malignant transformation.

Conclusion

The most common location for the cyst was the mandible, and multilocular radiolucency was the most prevalent radiological finding. Enucleation with CS was the most commonly used surgical modality, used in more than half of the patients, with only six patients experiencing recurrence.

The Incidence of Devitalization of Vital Teeth Associated with Pathologies of the Jaws Following Surgical Intervention: A Mixed-case Study

AIM

The purpose of this mixed-case study is to explore the incidence of pulp necrosis of vital teeth after surgical treatment of adjacent lesions of the jaws.

MATERIALS AND METHODS

The records of 341 biopsies submitted to the institute's histopathology laboratory were reviewed to include cases that met the inclusion criteria. About 84 biopsies collected from patients during surgical enucleation of lesions in proximity to healthy vital teeth were included of which 22 patients were recalled. Adjacent teeth were examined clinically and radiographically to assess their pulpal and periapical status after at least 8 months of follow-up.

RESULTS

There were 7 different pathological lesions diagnosed histologically. The follow-up period ranged between 8 and 72 months; 12 cases (54.6%) have developed pulpal necrosis for at least one tooth after surgical enucleation of the lesion. The other 10 cases (45.4%) showed normal responses to sensibility testing for all the teeth adjacent to the lesion. Ten out of the 12 cases (83%) that underwent pulpal necrosis were associated with odontogenic cysts, whereas the remaining 2 were associated with periapical granuloma and fibrous dysplasia.

CONCLUSION

Pulp necrosis is high in vital teeth associated with lesions without pulpal involvement. These teeth may benefit from root canal treatment prior to surgical enucleation of the lesion, which may prevent impaired healing or recurrence of infection.

CLINICAL SIGNIFICANCE

Careful treatment planning and thorough discussion should take place between the surgeons, endodontists, and patients prior to executing the treatment. The patient should be aware that there is a possibility that they may need root canal treatment as a preventative measure to enhance the chances of healing following the surgical procedures and in case the patients opted not to perform root canal treatment beforehand, close follow-up in the future should take place to monitor the vitality of the teeth in the follow-up visits.

Appearance and recurrence of odontogenic keratocysts

OBJECTIVE

The purpose of this study was to evaluate the appearance, histopathological features, and recurrence of odontogenic keratocysts (OKCs) from a large single institute registry over a 36-year period.

MATERIALS AND METHODS

A total of 226 cases of OKC were identified in 174 patients over a 36-year period in a single institute in Southwestern Finland. Histological specimens were re-evaluated. The patient's age, sex, location, recurrence, and histopathological features of the OKC were the study variables.

RESULTS

OKCs occurred more frequently in men, the mean age was 46 years, and the most frequent site was the lower jaw. Recurrence rate was 21%. Histopathologically, inflammation was present in 95% and satellite cysts in 10% of cases. In patients diagnosed with satellite cysts, OKC recurred in 50% of cases, while the corresponding figure for patients without satellite cysts was 17%.

CONCLUSIONS

Compared with the literature, patients were older and inflamed cysts were found more frequently. Satellite cysts occurred only in association with chronic inflammation. Based on the results, regular radiographic evaluation is important among patients aged 10-29 years to detect OKCs and to treat them before enlargement, infection, and inflammation. Satellite cysts should be reported and may be a sign of increased risk of OKC recurrence.

Volumetric reduction in large cystic jaw lesions postoperative enucleation: a longitudinal clinical study

BACKGROUND

Enucleation, a surgical procedure, is commonly used to treat large jaw cysts, unicystic ameloblastomas and keratocysts. However, it remains unclear to what extent the jaw bone regenerates after enucleation. We aimed to evaluate the percentage and the survival analysis of jaw bone regeneration, in terms of cavity volume residual (CVR), in patients who underwent enucleation of large jaw cysts, unicystic ameloblastomas and keratocysts.

METHODS

We collected data longitudinally from 75 patients who underwent jaw cystic lesions enucleation at the Stomatological Hospital of Xi'an Jiaotong University, between January 2015 and June 2021. All patients had both preoperative and postoperative cone-beam computed tomography (CBCT) imaging data. CBCT images were analyzed using Image J. Changes in the CVR were assessed at various follow-up time points, and the Kaplan-Meier method was utilized to evaluate the CVR over time.

RESULTS

The patients had a mean age of 31.7 years (range: 5.5-72 years) with 58.66% of them being male. The postoperative CVR was 32.20% at three months, 21.10% at six months, 15.90% at 12 months, and 5.60% at 24 months. The percentage of CVR during follow-up periods for the initial size Quartile (Q)1 (212.54-1569.60 mm3) was substantially lower than those of Q2 and Q3 at and after seven months of follow-up and became statistically significant at the 12-month mark.

CONCLUSION

This study demonstrates that spontaneous bone regeneration can occur after enucleation of large jaw cysts, unicystic ameloblastomas and keratocysts, even without the use of filler materials. The initial size of the lesion had a significant impact on the outcome of cystic lesion enucleation over time. To minimize the risks associated with radiation exposure and expenses, we recommend reducing the frequency of CT imaging follow-ups for patients with small initial cavity sizes (ranging from 212.54 to 1569.60 mm3).

The Role of 5-Fluorouracil in Preventing Recurrence After Enucleation of Odontogenic Keratocyst: A Case Report

The odontogenic keratocyst (OKC) is known for its high recurrence rate and disputed treatment modalities. In this report, we review the literature elucidating the efficacy of 5-fluorouracil (5-FU) topical application for recurrent OKC, and discuss the management of an OKC with 5-FU after enucleation and a 12-month follow-up. A 38-year-old female patient with an aggressive OKC in the right mandible underwent surgical curettage followed by topical application of 5-FU. Regular follow-up examinations for 12 months (radiological evaluation at three, six, and 12-month intervals) showed no signs of recurrence, with complete resolution of the cystic lesion and gradual bone regeneration. New bone formation was identified in the radiographic follow-up.  This case demonstrates the potential efficacy of topical 5-FU as a promising treatment modality for OKC, warranting further research and validation. A novel and successful therapy for OKC is the topical application of 5-FU. After enucleation, topical application of 5-FU efficiently treats OKC, leading to normal bone healing and regeneration without any adverse local or systemic effects.

Clinical indications for radical resection of odontogenic keratocyst: A systematic review

The aim of this study was to identify clinico pathological indications for radical resection of odontogenic keratocysts (OKCs) in the literature and formulate clinical guidelines for the management of OKCs based on these findings. A systematic review of the literature was undertaken in September 2021 in PubMed/Medline, Scopus, Web of Science, Google Scholar, and Cochrane databases. The following MeSH Keywords terms were used in the search strategies: (odontogenic keratocyst) OR (keratocystic odontogenic tumor) OR (primordial cyst) AND (treatment) OR (Radical resection) OR (Resection of OKC) OR (Treatment methods). Eligibility criteria included publications of clinical studies on histologically confirmed OKCs which underwent radical resection. Studies with less than 5 OKCs, experimental studies, epidemiological studies, studies that included orthokeratinized odontogenic cyst, and review papers were excluded. Ten studies on OKCs reporting on segmental or marginal resections were identified and analyzed qualitatively. Of the total of 221 OKCs that underwent radical resection, 67 OKCs were primary, 30 were recurrent, and the remaining were unclear whether they were primary or recurrent. Segmental mandibulectomy was performed in 131 OKCs, marginal mandibulectomy in 87 OKCs, and 3 OKCs were treated by partial maxillectomy. The main indications for radical resection were multilocular appearance, large OKCs (> 5 cm), multiple recurrent OKCs with or without cortical perforation, and malignant transformation. In conclusion, radical resection has its place in the management of OKC. It is indicated when there is an aggressive lesion with bony perforation, involvement of the pterygoid musculature or skull base, and malignant transformation. The surgeon should aim to identify these features to manage OKC appropriately and to prevent multiple recurrences. Clinical guidelines for the management of OKCs are proposed.

Various Surgical Interventions in Treating Odontogenic Keratocyst: A Radiological Case Report

The odontogenic keratocyst (OKC) is among the most aggressive odontogenic cysts because of its high recurrent rate. This study's objective was to describe a 7-year radiological and clinical follow-up of an OKC with two recurrences and a combination of surgical treatments. The cyst contents were drained at the biopsy to allow decompression, and then marsupialization (Partsch I) was carried out with good results. In the following two years, the endodontic and radiological evaluation of the neighboring teeth indicated endodontic avoidance. The remaining OKC enucleation (Partsch II) with chemical curettage and suture was performed two years after the first presentation, and the multifocal recurrences developed were also treated by enucleation and chemical curettage. At the last radiological follow-up, no recurrence was evident. Based on our experience, we concluded that patients diagnosed with a OKC should be radiologically evaluated at least once a year for at least 7 years, the endodontic diagnosis and treatment of neighboring teeth should be performed as early as possible, and the combination of surgical treatment and the long follow-up period is challenging.

Frequency and Demographic Profile of Odontogenic Cysts in Riyadh, Saudi Arabia: Retrospective Multicenter Study

Odontogenic cysts (OCs) are etiologically diverse conditions with a shared origin in the jaws. Unfortunately, there is a scarcity of published data regarding OC frequency, treatment, and follow-up information in Saudi Arabia, especially from tertiary centers.

OBJECTIVES

The study aims to assess the relative frequency, clinicopathological features, treatment, and follow-up of OCs in three tertiary medical centers.

METHODS AND MATERIAL

OCs were identified from King Abdulaziz Medical City, King Fahad Medical City, and Prince Sultan Military Medical City from January 2010 to December 2021.

RESULTS

Three hundred and seventy-two cases of OCs were identified from the archive of three medical centers in Riyadh; one hundred and forty-nine (40%) cases were retrieved from Prince Sultan Military Medical City. The mean age of all OCs was 32 years (range 2-90), with 225 (60.4%) cases occurring in males. There was an almost equal distribution of OCs between the maxilla (47.0%) and the mandible (53.0%). The apical radicular cyst (ARC) accounted for half of the cases, followed by dentigerous cyst (DC) (29.3%) and odontogenic keratocyst (OKC) (14.2%). Enucleation was the most common treatment modality (52.8%), followed by excision (35.0%). Thirteen cases showed recurrence: one ARC, four DCs, and eight OKCs.

CONCLUSION

This is the first large multicenter study of OCs in Riyadh, Saudi Arabia. All three centers showed that ARC was the most common, followed by DC and OKC.

Management of multiple odontogenic keratocysts associated with nevoid basal cell carcinoma syndrome: a case report of 11-year follow-up

Multiple odontogenic keratocysts (OKC) are a distinguishing feature of nevoid basal cell carcinoma syndrome (NBCCS). Owing to the high recurrence rate of syndromes associated OKCs, complete surgical resection is generally recommended as a definitive treatment. Herein, we report the management of multiple OKCs with marsupialization followed by excision with peripheral ostectomy in an NBCCS patient. We then discuss lesion progression over 11 years of annual follow-ups.

Management of radicular cyst associated with primary teeth using decompression: a retrospective study

BACKGROUND

Radicular cysts arising from primary teeth are rare. Enucleation and marsupialization or decompression are treatment approach to odontogenic cysts. Decompression known to achieve good results in various cysts is widely used in clinic. This study aims to evaluate the efficiency of decompression in reducing radicular cysts associated with primary teeth in children.

METHODS

Cases of radicular cysts associated with primary teeth treated by decompression were reviewed in the present study. Clinical information and radiologic data of pre and post decompression were measured and analyzed.

RESULTS

Twenty-three patients treated for 25 cysts were included. All lesions with mean initial area 3.66 ± 2.00 cm² were reduced after decompression time ranging 2 to 10 months. Mean rate of reduction was 0.77 ± 0.44 cm²/mo and large lesions (> 3.5 cm²) had a significantly higher reduction rate compared to smaller ones (< 3.5 cm²) (P < 0.00). All effected succedaneous teeth erupted after treatment at follow-up while 12 (46%) of them had root development problems.

CONCLUSIONS

Decompression represents superiority as an effective and less invasive treatment in radicular cysts associated with primary teeth.

TRIAL REGISTRATION

This study was retrospectively registered in the Ethics Committee of Ninth People's Hospital Affiliated with Shanghai JiaoTong University School of Medicine (No.SH9H-2022-T158-1).

Volumetric analysis of spontaneous bone healing after jaw cyst enucleation

The purpose of this study is to evaluate the degree of spontaneous bone healing after cyst enucleation as well as its contributing factors. Pre- and post-operative computed tomography (CT) scans of consecutive patients who had undergone jaw cyst enucleation were retrospectively analyzed. The outcome variable was healing ratio, which was calculated using the volume of the cyst before surgery and the volume of the defect in the bone after surgery. Predictor variables including duration of observation, pre-operative cyst size, age, gender, and involved jaw were analyzed to determine their influence. Forty-four subjects (30 Male and 14 Female, average 40.7 ± 15.7 years) were included in this study. Healing ratio was significantly lower during the first year (33.5 ± 32.8%) compared to the second (74.5 ± 24.2%) and subsequent years (74.2 ± 17.8%). In 35 patients who had follow-ups of over 1 year, the healing ratio was not affected by the pre-operative cyst size and upper/lower jaw except gender (p = 0.037, female > male) and age (p = 0.021, younger than 30 years > 30 years and older). The residual defect was significant larger in cysts 3 cc or larger (1.64 ± 1.54 cc) compared to smaller cysts (0.43 ± 0.42 cc, p = 0.006). The residual defect volume of large cysts was similar to those of the pre-operative volume of small cysts (1.47 ± 0.72 cc). In conclusion, spontaneous bone healing ratio of post-enucleation defects was about 73.5% after 12 months. Large cysts (> 3 cc) had larger defect, comparable to the volume of small cysts, but with altered contour. Additional treatment such as a bone graft may be considered especially in large cysts.

[Clinical radiological evaluation of teeth-part 2 : Caries, inflammatory dental changes and important differential diagnoses]

Inflammatory diseases of the teeth and periodontium are widespread and are frequent secondary diagnoses in head and neck examinations. Periapical inflammation can be the cause of sinusitis or abscess formation in the oral and maxillofacial region. Early detection is important for the patient's course of treatment. For further diagnostics, a dental presentation should be carried out. Dental radiological examinations, such as panoramic radiographs and dental films are used for specific diagnostics. This article is intended to provide an overview of the different stages of caries, the most important inflammatory dental changes and their most frequent differential diagnoses.

Marsupialization of odontogenic keratocyst using thermoform surgical splint in a pediatric patient, with 3-year follow-up

Odontogenic keratocyst (OKC), also known as keratocystic odontogenic tumor, is categorized as one of the developmental epithelial cysts, which accounts 10%–20% of all cystic lesions in jaws. Considering its high recurrence rate, combative treatment modalities such as enucleation and jaw resection are suggested. This case report aims to emphasize clinical, radiological and histological overview of OKC with conservative approach marsupialization using thermoform surgical splint in a 9-year-old female patient with no recurrence at 3-year follow-up.

Orthokeratinized versus parakeratinized odontogenic keratocyst: Our institutional experience

Introduction

The odontogenic keratocyst (OKC) is quite unique among odontogenic cysts in its specific histological features and in clinical characteristics. The OKC has two variants orthokeratinized odontogenic cyst (OOC) and parakeratinized odontogenic cyst (POC), and POC is considered to be more aggressive and has a high recurrence rate. Therefore, OKC has generated considerable controversy with regard to its true nature.

Aim

The purpose of this study was to determine the differences between POC and OOC variants of odontogenic cysts on the basis of clinical as well as radiological features.

Materials and Methods

A total of 85 cases were included in the present study. There was a marked difference in the age of occurrence, sex, location and radiological presentation of both these entities.

Results

Our institutional experience suggests that POC is more common than OOC and both the variants were commonly found in males. Most of the cases of POC were found in the third decade of life and most of the cases of OOC were frequently seen in the second, fourth and fifth decades. Mandibular posterior area was frequently occurring in both variants. Left side involvement was seen in maxilla and right side in mandible in both variants. Most of the cases were clinically diagnosed as OKC.

Conclusion

The treatment and prognosis varies in both the variants of OKC, hence such epidemiological studies are helpful to ensure proper treatment for these distinct entities.

Differential Expression of Claudin in Odontogenic Cysts

Objective  This study aimed to analyze claudin-1, -4, and -7 expression in different types of odontogenic cysts (odontogenic keratocysts [OKCs], dentigerous cysts [DCs], calcifying odontogenic cysts [COCs], and radicular cysts [RCs]) as well as its association with OKC recurrence.

Materials and Methods  Seventy samples of odontogenic cysts samples were immunohistochemically stained to detect claudin-1, -4, and -7 expression. Patient information and OKC recurrence data were recorded. The staining was analyzed semiquantitatively and categorized based on the pattern and percentage of positively stained cystic epithelial cells.

Statistical Analysis  Expression of different claudins between groups was analyzed using the Kruskal–Wallis test with Dunn's test, followed by post hoc pairwise comparison. The association between claudin expression and OKC recurrence was analyzed by the Mann–Whitney U test. Correlations among claudin expression were examined with Spearman's correlation coefficient. Level of significance was at p  < 0.005.

Results  Claudin-1 was widely expressed in every odontogenic cyst. Most DCs (50%) expressed claudin-1 in more than 75% of cells, as did RCs (65%), while most OKCs (50%) expressed claudin-1 in 26 to 50% of cells. Most COCs (50%) expressed claudin-1 in 51 to 75% of cells. Every sample of OKC and RC was positive for claudin-4, but no sample showed staining in more than 51% of cells. Every odontogenic cyst was positive for claudin-7. DCs (35%), OKCs (55%), and RCs (40%) mostly showed staining in 26 to 50% of cells. High claudin-1 expression was shown in COCs, DCs, and RCs, while low expression of claudin-4 was shown in every odontogenic cyst. For claudin-7, the expression is high only in COCs. Claudin-1 and -4 was significantly different among each odontogenic cyst. High expression of claudin-1 was correlated with OKC recurrence. The correlations of claudin-1 with claudin-7 expression and claudin-4 with claudin-7 expression were significant in DCs. In COCs, claudin-1 and claudin-7 expression was significantly correlated.

Conclusions  The expression of claudin-1, -4, and -7 was present in every odontogenic cyst, but the proportion of positive staining cells was different. Expression of claudin-1 is associated with OKC recurrence. Dysregulation of claudin expression may play a pathogenic role in cyst pathogenesis.

The epidemiology and management of odontogenic keratocysts (OKCs): A European multicenter study

The objective of the present study was to assess the epidemiology including demographic variables, diagnostic features, and the management of odontogenic keratocyst (OKCs) at several European departments of maxillofacial and oral surgery. This study is based on a systematic computer-assisted database that allowed the recording of data from treated OKCs. The following data were recorded for each patient: gender, age, voluptuary habits, comorbidities, site, size, radiographic features, treatment of OKCs, length of hospital stay, complications, recurrence, management and complications of eventual recurrence. A total of 405 patients, 249 male and 156 female, with 415 OKCs (407 sporadic and 8 syndromic lesions) were included in the study: 320 lesions were found in the mandible, whereas 95 were found in the maxilla. In the mandible, the most frequently involved subsite was the angle, whereas in the maxilla it was the molar region. The most frequently performed treatment option was enucleation plus curettage/peripheral ostectomy in 204 OKCs (recurrence rate, 9%). Decompression without residual cystectomy (recurrence rate, 66%), marsupialization with residual enucleation with the use of Carnoy's solution (recurrence rate, 50%), decompression with residual cystectomy (recurrence rate, 43%), and simple enucleation (recurrence rate, 24%) were the treatment options with the highest recurrence rates. An appropriate management of odontogenic keratocysts should be individualized, taking into consideration clinical and radiological findings, as well as patients' age and comorbidities.

A Volumetric and Morphological Analysis of Recurrent Odontogenic Keratocysts by Semiautomatic Segmentation

PURPOSE

The authors conducted this study to provide morphological and volumetric data of recurrent odontogenic keratocysts of the upper and lower jaw to emphasize risk factors in accordance with their radiological appearance and guide clinical decisions for jeopardized patients.

METHODS

By applying the open-source software "ITK-Snap" on cone-beam computed tomography images, volumetric measurements of histopathologically diagnosed recurrent odontogenic keratocysts could be performed. For statistical investigations, descriptive statistics and independent Student t test were performed. The intraclass correlation coefficient was used to assess intra- and inter-rater reliabilities. P values P < 0.05 were considered significant.

RESULTS

Forty patients (24 male and 16 female) were included in this study. Recurrent odontogenic keratocysts had a mean maximum diameter of 28.91 mm ± 12.00 mm and a mean volume of 4.48 cm3 ± 4.29 cm3. According to morphology, irregular shape (P = 0.001; P = 0.005), unclear margin (P = 0.001; P = 0.001), multilocular morphology (P = 0.001; P = 0.001), and cortical bone exceedance (P = 0.001; P = 0.007) are statistically significantly associated with a larger cyst diameter and volume. Furthermore, significant differences by diameter and volume could be shown between patients with and without iliac crest graft reconstruction (P = 0.001; P = 0.001).

CONCLUSIONS

Volumetric analysis reveals that recurrent odontogenic keratocysts show large diametric and volumetric extension that leads to complex reconstruction by iliac crest grafts, adding an argument that special attention should be paid to this entity and its recurrence. In case of difficult histopathological examination, lesions with irregular shape and margin, multilocular morphology, cortical bone exceedance, and clinically visible symptoms should be considered for close morphological and volumetric clinico-radiological follow-up.

A comparative immunohistochemical analysis of cortactin in orthokeratinized odontogenic cyst (OOC), sporadic odontogenic keratocyst (OKC), and syndromic OKC

OBJECTIVES

To evaluate and compare the immunohistochemical expression of cortactin in the epithelial lining of orthokeratinized odontogenic cyst (OOC), sporadic odontogenic keratocyst (OKC), and syndromic OKC.

METHODS

Formalin-fixed paraffin-embedded tissue blocks of histopathologically diagnosed cases of OOC, OKC, syndromic OKC, normal buccal mucosa (NBM), and oral squamous cell carcinoma (OSCC) were examined for immunohistochemical expression of cortactin. Clear brown cytoplasmic and membranous staining was considered positive.

RESULTS

A statistically significant difference was observed between OOC and syndromic OKC (p<0.001), as well as between sporadic OKC and syndromic OKC (p<0.001). Although not statistically significant, the expression of cortactin was slightly higher in the basal layer of NBM (mean=0.47), OOC (mean=0.27), sporadic OKC (mean=0.47) syndromic OKC (mean=1.53), and OSCC (mean=0.67) than in the parabasal layers of NBM (mean=0.27), OOC (mean=0.20), sporadic OKC (mean=0.47), syndromic OKC (mean=1.27), and OSCC (mean=0.60).

CONCLUSION

The expression of cortactin in the basal layer may suggest the formation of invadopodia in the basal layer where the invasion mechanism occurs. This finding is further supported by the higher localization of cortactin in areas of epithelial budding and daughter cysts in syndromic OKC, thereby reaffirming its possible association with recurrence.

Modified Carnoy's Compared to Carnoy's Solution Is Equally Effective in Preventing Recurrence of Odontogenic Keratocysts

PURPOSE

Carnoy's solution (CS), the gold standard for adjunctive chemical cautery in treatment of odontogenic keratocysts (OKCs), has been banned for 7 years, leading to substitution with the non-chloroform containing modified Carnoy's solution (MC) without data to support its effectiveness. We performed this study to compare the earlier data with CS to the more current outcomes with MC.

METHODS

A retrospective cohort study was conducted on patients diagnosed with OKC and treated by a single surgeon (GHB) with enucleation and curettage (EC), peripheral ostectomy, and application of CS or MC. The primary predictor variables were use of CS or MC. The primary outcome variables were recurrence (yes vs. no) and time to recurrence. Secondary variables included demographics, anatomic location, and whether teeth adjacent to the lesion were extracted. Statistical analyses included chi-squared test/Fisher's exact test, Wilcoxon rank sum test, and Kaplan-Meier curves.

RESULTS

77 patients, 36 patients in the CS group and 41 in the MC group, met inclusion criteria, including at least 1 year of follow-up time. Characteristics of the groups were similar: median age 41.5 and 46, 61% and 71% male gender, 81% and 90% posterior, and 64% and 50% mandibular lesions, respectively. Overall recurrence was similar, 14.29%, with 5 (13.9%) recurrences in the CS group and 6 (14.6%) in the MC group (P = 0.92). Median time to recurrence was 24 months for both groups. Preserving adjacent teeth was associated with a significant increase in recurrence (P = 0.0036).

CONCLUSION

Based on this comparison of retrospective outcome data, we found no significant difference in recurrence rate or distribution of time to recurrence between OKCs treated with CS or MC. Aggressiveness of surgical technique is likely a predictive factor in recurrence rate. Future studies should focus on prospective studies and continuing follow-up of the MC group.

Appropriate follow-up period for odontogenic keratocyst: a retrospective study

Purpose

The aim of this study was to conduct epidemiologic investigations on the pattern of the lesion and differences between treatment modalities in terms of recurrence by reviewing follow-up records to form a basis for planning patient follow-up visits.

Materials and methods

In this retrospective, single-center cohort study, 266 patients diagnosed with odontogenic keratocyst between 1993 and 2013 were included. Medical records and radiographic images were analyzed for age distribution, occurrence site and size, treatment modalities, and recurrence.

Results

The average age at first diagnosis was 33.1 years, and the male to female ratio was 1.33:1.00. The highest rate of incidence was in the third decade followed by the fourth, second, and fifth decades. The incidence in the maxilla was 34%, and 66% in the mandible. Mandibular ramus was most commonly involved. Lesions between 3 and 6 crowns were the most common, and the rate of recurrence increased with size. Enucleation after decompression had higher rate of recurrence (35.8%) than enucleation (27.1%), but there was no statistical significance.

Conclusion

The recurrence of odontogenic kerotocyst (OKC) was significantly associated with large size, multilocular form, and surgical procedure. A 10-year follow-up period is recommended to determine any recurrence of OKC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40902-021-00301-x.

Novel recurrence risk stratification of odontogenic keratocysts: A systematic review

The aim of this study was to identify all clinical, radiological, histopathological, and immunohistochemical features associated with recurrence of odontogenic keratocysts (OKCs) in the literature and formulate a recurrence risk stratification based on these findings. A search was performed in PubMed/Medline, Scopus, Web of Science, Google Scholar and Cochrane databases for clinical and laboratory studies reporting on clinico-pathological features that led to OKC recurrences for the period 2000 to 2020. Twenty-three studies were identified and analyzed qualitatively. A total of 2064 OKCs were included of which 439 OKCs were recurrent with a mean follow-up period of 46.7 months. Significantly associated parameters with OKC recurrence included age (variable age categories), large (>4 cm), multilocular lesions with cortical perforation, association with dentition, presence of daughter cysts, and epithelial budding. Immunohistochemical markers including high Ki67 index and AgNOR count were also implicated. A recurrence risk stratification was formulated based on these findings. Although the level of evidence from the included studies was low, there was considerable evidence that the clinico-pathological parameters identified were linked with higher OKC recurrence. The surgeon, radiologist, and pathologist should aim to identify these features when making a diagnosis so as to determine the appropriate management regime and prevent recurrences.

Sub-epithelial hyalinization, incomplete cystic lining, and corrugated surface could be a predictor of recurrence in Odontogenic Keratocysts

BACKGROUND

Odontogenic Keratocysts (OKCs) are known for their rapid growth and tendency to invade the adjacent tissues. Its high recurrence rate (2.5%-62%) has attracted many kinds of research to identify new parameters to predict recurrence that would enable better treatment outcomes for such patients. The present study aims to correlate Sub-Epithelial Hyalinization (SEH) that has not been explored in an Asian population to date and other histopathologic features of OKC to its recurrence propensity.

MATERIALS & METHODS

A total of 60 OKCs were analyzed for histopathologic correlation of thickness of lining, complete/incomplete lining, corrugated surface, ortho/para keratinization, intercellular edema, reversed polarity, basilar hyperplasia, the palisading arrangement of basal cells, presence/absence of rete pegs, folding of the epithelium, epithelial/connective tissue separation, SEH, basal offshoots, daughter cysts and inflammation with recurrence to arrive at the most significant histologic feature predicting recurrence.

RESULTS

The most significant histologic parameter differentiating recurrent and non-recurrent OKCs was the presence of SEH (p = 0.004), incomplete lining epithelium (p ​= ​0.023), and a corrugated surface (p ​= ​0.049). Several other histologic parameters evaluated did not statistically correlate with recurrence, this can be attributed to the smaller sample size considered in the present study.

CONCLUSION

SEH is a reliable histologic parameter to predict recurrence in OKCs. The presence of SEH is indicative of a higher recurrence potential in OKCs. Evaluation of histological parameters and their correlation with recurrence in OKCs on a larger sample size could validate the results of the current study undertaken and potentially unravel more insights on predicting recurrence.

KEY MESSAGES

Sub-epithelial hyalinization is a significant feature for predicting recurrence in OKC.

Diagnosis and Treatment of Pediatric Primary Jaw Lesions at Massachusetts General Hospital

PURPOSE

To review the demographic data, presenting symptoms, location, radiographic findings, treatment, and prognosis of pediatric jaw lesions in children treated at a single academic institution.

PATIENTS AND METHODS

A retrospective medical record review was undertaken of patients younger than 18 years who presented to the Massachusetts General Hospital for Children between 2006 and 2018 with a primary jaw lesion.

RESULTS

About 164 patients were identified. The most common lesions were giant cell tumors (n = 25), odontogenic keratocysts (n = 24), simple bone cysts (n = 19), odontomas (n = 17), fibrous dysplasia (n = 11), and dentigerous cysts (n = 11). Fifty-one patients (30.7%) were asymptomatic. About 94% were referred by their dentist, outside oral and maxillofacial surgeon or orthodontist. Most common presenting symptoms were swelling (66.9%), pain (32.5%), tooth mobility (17.5%), and neurosensory change (6.6%). Mandibular location was most common (72.3%). Radiographically, most were well-circumscribed radiolucencies with mean size of 2.9 cm (range, 0.7 to 15.6). Treatment varied from excisional biopsy to wide composite resection. Mean follow-up time was 38 months (range, 1 to 204). Recurrence was found in 21%.

CONCLUSIONS

Pediatric jaw lesions are often asymptomatic and discovered incidentally by dental practitioners on routine examination. Clinical features (age, gender, location, and radiographic appearance) can help narrow the differential and expedite treatment. It is important that clinicians involved in the care of children be familiar with the wide differential diagnosis and management considerations of primary jaw lesions.

A rare case of odontogenic keratocyst extending into the sphenoid bone from the maxilla

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Odontogenic keratocyst (OKC) is the third most common odontogenic cyst which arises from cell rests of dental lamina.

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Because of high rate of recurrence, there are various treatment strategies.

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OKC is usually observed in the jaws.

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We report on a rare case of OKC which involved the maxillary sinus extending into the sphenoid bone nearly to the skull base.

Background

Odontogenic keratocyst (OKC) is the third most common odontogenic cyst which arises from cell rests of dental lamina, and usually observed in the jaws. Because OKC is noted for its high rate of recurrence, there are various treatment strategies. Here, we present a rare case of OKC which occupied the entire maxillary sinus and pterygoid process of the sphenoid bone extending nearly to the skull base.

Case presentation

The patient was a 21-year-old male and underwent surgical removal of the cyst using the Caldwell-Luc procedure which in this case extended the surgical approach to the pterygoid process of the sphenoid bone via the pterygomaxillary junction. However, we found a recurrent lesion in the posterior wall of the maxillary sinus 20 months after the surgery and subsequently performed a secondary cystectomy. Surgical specimens showed positive bcl-2 staining of OKC and negative cytokeratin-10 on immunohistochemistry for both primary and recurrent lesions.

Conclusion

OKC rarely occurs in the maxillary sinus and extends to the deep maxillary structure and the skull base. In order to prevent recurrence, it is necessary to recognize the exact location of the entire lesion. Careful examination of preoperative CT images is needed to make a complete surgical planning and to perform a reliable surgical procedure.

Evaluation for noncompliance of recall in patients reporting to oral pathology department: Longitudinal study of 5 years

Background:

Regardless of the form of treatment, long-term follow-up of the patient is an absolute necessity. This study aimed to follow surgically treated patients visiting our department of oral pathology over 5 years (January 2011–December 2015) to monitor recurrence of the condition, patient compliance and reasons for noncompliance.

Materials and Methods:

We conducted half-yearly recall for patients visiting our department from January 2011 to December 2015. Patients were recalled through the use of letters, telephonic reminders and e-mails.

Results:

The study included 171 recalled patients of whom, 42 (24.56%) reported for follow-up, while the remaining 129 (75.43%) did not report for follow-up. Of the 42 reporting patients, 26 (61.90%) reported once, 10 (23.81%) twice and 6 (14.28%) three times. Recurrence of the condition was reported in two cases. The reasons for noncompliance included: financial constraints (22.48%), casual attitude (37.20%), reported to nearby hospitals (5.42%) and lack of time (11.62%). Some patients could not be sent reminder letters due to incomplete address (7.75%), the wrong pin code (6.97%), change of address (4.65%), locked house (3.10%) and death of the patient (0.77%).

Conclusion:

This study highlights patient recall appointment noncompliance, ascribing various reasons to the patient's attrition rate for recall appointments. Probable solutions for increasing the compliance for recall need to be addressed, and further research should be conducted to evaluate these solutions.

Odontogenic keratocyst: Analysis of recurrence by AgNOR, p53 and MDM2 profiling

Background:

Odontogenic keratocyst (OKC) is a clinical entity with characteristic microscopic features, high growth potential and propensity to recur. Aggressive behavior and higher tendency for recurrence have been attributed to greater proliferative activity of epithelial lining. The incidence of recurrence in various reported series ranges from 2.5% to 62%.

Objectives:

The objective of the study was to investigate the clinical behavior of OKC by evaluating p53, MDM2 expression, AgNOR staining and to ascertain if the expression of these markers correlate with the clinical outcome and tendency for recurrence.

Materials and Methods:

All recurrent and nonrecurrent OKCs from the archives were included, and sections were subjected to AgNOR staining, p53 and MDM2 immunohistochemical staining.

Results and Conclusion:

There was a significant difference in the staining pattern of MDM2 and AgNOR in the recurrent group as compared to the nonrecurrent group. The higher expression of these markers in recurrent lesions may be important in order to consider additional surgical interventions to improve prognosis.

Is odontogenic keratocyst an endodontic enigma? A rare case report of management of odontogenic keratocyst in anterior mandible

Odontogenic keratocyst (OKC), a rare, locally aggressive developmental cyst, is found incidentally on dental radiographs, most commonly in the posterior mandible. When it occurs in the periapical region in association with nonresponding teeth to pulp sensibility tests, it is often misdiagnosed as other endodontic lesions such as radicular cyst, lateral periodontal cyst and dentigerous cyst. This case report describes the rare occurrence of OKC in the anterior mandibular region managed successfully with endodontic treatment and re-interventional surgery in a conservative approach. This case report also emphasizes on the importance of histopathological examination of the surgically excised tissue specimens as the clinical, radiographic and histopathological correlations are essential for successful treatment.

Odontogenic keratocyst and ameloblastoma: radiographic evaluation

OBJECTIVES

To describe the radiographic features of odontogenic keratocysts (OKCs) and ameloblastomas and to compare the radiographic findings between these 2 lesions.

METHODS

Radiographs of OKCs and ameloblastomas were retrospectively reviewed. Location, border, shape, association with impacted tooth, tooth displacement, root resorption, and bone expansion were evaluated. Chi-squared or Fisher's exact tests were used for statistical analysis. A p value < 0.05 was considered to indicate statistical significance.

RESULTS

One hundred OKCs and 101 ameloblastomas were reviewed. The ratios of maxilla to mandible were 1:1.4 and 1:9.1 in OKCs and ameloblastomas, respectively. All evaluated features significantly differed between OKCs and ameloblastomas (p ≤ 0.001). Most OKCs showed smooth border (60%) and unilocular shape (82%), while most ameloblastomas showed scalloped border (77.2%) and multilocular shape (68.3%). Association with impacted tooth was found in 47% of OKCs and 18.8% of ameloblastomas. Adjacent tooth displacement was found in 33.7% of OKCs and 55.8% of ameloblastomas. Root resorption was more common in ameloblastomas (66.7%) than in OKCs (7%). Bone expansion was also more common in ameloblastomas (96.3%) than in OKCs (63.6%).

CONCLUSION

A unilocular radiolucent lesion with smooth border, no adjacent tooth displacement, no root resorption and causing mild or no bone expansion is suggestive of an OKC rather than an ameloblastoma.

Nonsyndromic Examples of Odontogenic Keratocysts: Presentation of Interesting Cases with a Literature Review

The odontogenic keratocyst (OKC) may occur at any age. However, it mostly occurs during the second and third decades of life. Compared to other odontogenic cysts, this type occurs with a frequency of 5-15%. It is more common in the mandible region and in the male sex. Histologically, odontogenic keratocysts are characterized by the presence of an external connective tissue capsule, with keratinizing lining of the epithelium consisting of 5-8 cell layers with marked palisadisation of polarized basal cells and a corrugated parakeratin layer. The objective of this study is to present cases of odontogenic keratocysts, with reference to the latest classification and dilemmas in therapeutic doctrine. This project was realized in the form of descriptive studies, specifically in a series of cases. A collection of four individual cases was found at the Department of Oral Surgery. Due to the proper approach towards diagnosis, adequate and detailed histopathological analysis, and suitable therapeutic procedures, all cases of odontogenic keratocysts were successfully treated without complications. Enucleation of OKC, with a regular follow-up, proved to be the effective therapeutic choice for the patients described in this paper. Only in the case of recurrence would we consider other therapeutic options, primarily enucleation in combination with Carnoy's solution.

The Changing Landscape in Treatment of Cystic Lesions of the Jaws

Objective:

Cystic lesions of the jaw are common pathologies of chronic swelling of the jaw in oral and maxillofacial regions. Different treatment modalities have been described in the literature. However, the existence and proper treatment of these cysts remains a contentious topic. The aims of this review were to discuss the complexity of various surgical treatment and as factors with potential to influence outcome treatment. Finally, a practical and a rational clinical guideline for the management of such lesions have been suggested.

Materials and Methods:

A literature search without language limitation was performed in 2018 using MEDLINE, PubMed, Scopus, and Embase. Keywords for the search included the following terms: jaws cyst, cystic lesions, odontogenic cysts, cystic tumors, pseudocysts, treatments, therapy, wound healing, bone regeneration, and teeth involved cysts. Prospective or retrospective clinical studies with a sample size of n ≥ 5 were evaluated and included in this review. The exclusion criteria were studies with unclear reporting of the treatment applied or outcome, nonhuman studies, case reports, letters, preface, comments, and cystic lesions associated to syndrome. After the full reading, 30 articles were included in the quantitative synthesis for the review. No meta-analysis could be performed due to the heterogeneity of the studies included. Clinical radiographic images were presented to illustrate the principles of some surgical treatments.

Conclusion:

Conservative surgery with primary closure defect (less than 4 cm) remains an initial approach, which reduces the morbidity of aggressive surgeries and obtains the complete bone healing before 24 months of postoperative. Marsupialization is considered as the most common option for the treatment of large cystic lesions when cases are carefully selected. Evocyst is an attractive new technique of obtaining complete bone defect healing within <3 months.

Management of mandibular odontogenic keratocyst through radical resection: Report of 35 cases

The present study reported the clinical outcomes of 35 patients with mandibular odontogenic keratocysts (OKCs) following treatment by radical resection and immediate defect reconstruction. Amongst 565 patients with OKCs that were treated between April 2003 and May 2015, 35 patients underwent segmental or marginal mandibulectomy. The use of radical resection was based on clinical and/or radiographic evidence of size, cortical perforation and subsequent soft tissue involvement, and on the history of previous recurrence of the same lesion. Recurrence, justifications of the main major factor for resection, and functional and cosmetic results of the patients following mandibular reconstruction were systematically evaluated. There were 26 OKCs in the mandibular molar-ramus region, eight in the mandibular anterior-premolar region and one in the mandibular molar-ramus and anterior-molar regions. Among the 35 patients, 20 had primary OKCs and 15 had recurrent OKCs. A total of 31 patients underwent segmental mandibulectomy, of which 28 were immediately reconstructed with a vascularized flap, whereas four patients underwent marginal mandibulectomy. The functional and cosmetic outcomes of patients were evaluated as satisfactory. The length of the follow-up period ranged from 2 to 17 years following operation (average, 5.82 years). Recurrence was identified in one patient who had been treated with marginal mandibulectomy. In conclusion, the findings from the present study suggested that radical resection may be recommended for patients with OKCs and locally aggressive features. Immediate mandibular reconstruction with a vascularized flap may be a crucial part of this aggressive treatment method that may reduce OKCs-associated morbidity.

Recurrence of odontogenic keratocysts and possible prognostic factors: Review of 455 patients

BACKGROUND

To describe epidemiological features of 565 Chinese patients with odontogenic keratocysts (OKC), to investigate possible prognostic factors related to recurrence, and to analyse features of recurrent OKC (rOKC).

MATERIAL AND METHODS

A retrospective chart review of 565 cases of OKC treated between 2003 and 2015 was undertaken. The probability of recurrence related to prognostic factors including large size, cortical perforation combined with involved teeth in the lumen of the cyst, inflammation, sites of the involved lesion, sex, and daughter cyst variables were analysed. The subsequent relapse of each OKC was compared.

RESULTS

Patients ranged in age from 7 to 81 years (mean age, 28.4 years) and, of those affected, 66.9% were male and 33.1% were female. Mandibular OKC occurred in 63.01% and 36.99% occurred in the maxilla, 80.53% of patients had non-rOKC, 10.44% rOKC, and 9.03% had multiple OKC lesions. Enucleation with preservation of the involved teeth in the cystic lesion combined with cortical perforation was statistically associated with high recurrence rate, as were daughter cysts, and multilocular lesions. The number of recurrences and the average time (in years) to relapse decreased from the first relapse of OKC to the third relapse, and the difference was significant (P<.05).

CONCLUSIONS

Preservation of the involved teeth combined with cortical perforation appeared to be a potential prognostic factor associated with high recurrence. The follow-up evaluation period for rOKC with ≥ 2 previous treatments should be shorter than for first-time rOKC. The decreasing average duration (years postoperatively) to relapse was related to the number of rOKCs, timing of relapse, and rOKC type.

The presentation of odontogenic keratocysts in the jaws with an emphasis on the tooth-bearing area: a systematic review and meta-analysis

PURPOSE

This study was conducted in order to gain insight in the actual ratio of odontogenic keratocysts occurring in the tooth-bearing area as compared to the posterior region of the jaws in order to come up with reliable data to base upon a rational treatment policy.

METHODS

We searched MEDLINE, Web of Science, Scopus, and Cochrane databases for studies reporting on the location of mandibular and maxillary odontogenic keratocysts. All records were independently assessed and a meta-analysis was performed. Risk difference with a confidence interval of 95% of having the lesion in the posterior region versus the tooth-bearing area was the effect measure. P value for the summary effect of < 0.05 was considered statistically significant.

RESULTS

The 2615 records retrieved were reduced to 34 studies to be qualitatively/quantitatively assessed. The pooled values showed that the difference in the clinical risk of having keratocysts in the posterior region of the mandible and in the tooth-bearing area of the maxilla is 21 and 43%, respectively (P < 0.02 and P < 0.00001).

CONCLUSIONS

A substantial amount of keratocysts occur in the tooth-bearing area of the jaws, requiring attention.

Investigation of Postoperative Complications of Intrabony Cystic Lesions in the Oral and Maxillofacial Region

PURPOSE

The purpose of this study was to identify factors that can complicate the surgical removal of intrabony cysts and any relevant correlations between them.

PATIENTS AND METHODS

The medical records of 249 patients who underwent surgical removal of intrabony cysts were retrospectively reviewed. Outcome variables were postoperative complications, infection, and recurrence. Predictor variables were patient age, gender, comorbidities, anatomic location, pathologic diagnosis, preoperative infection, previous marsupialization, and bone graft methods. Logistic regression analysis was performed to identify risk factors of postoperative infection and recurrence.

RESULTS

The cystic lesion was smallest in patients who did not receive a bone graft and increased steadily in those who received a xenogeneic bone graft and an autogenous bone graft, in that order. Paresthesia occurred after enucleation of the cystic lesion in 38 cases. Pathologic fractures were observed in 4 cases. There were 59 postoperative infections. The postoperative infection rate was as high as 63.6% in patients who underwent autogenous bone grafting. In contrast, infection rates were as low as 26.8 and 19.5% in those who underwent xenogeneic bone grafting and no bone grafting, respectively. Location of the cystic lesion in the maxilla or mandible affected the infection rate. When cysts were located in the anterior mandible, no postoperative infection occurred. In contrast, the infection rate was highest for cysts in the mandibular ramus, followed by those in the posterior mandible. Cystic lesion recurrence was observed in 7 cases: 5 cases of odontogenic keratocysts, 1 case of periapical cyst, and 1 case of dentigerous cyst. These findings suggest that cyst pathologic identity affects the recurrence rate. Cyst size was meaningfully correlated with recurrence rate.

CONCLUSIONS

These results suggest that autogenous bone grafts increase the risk of postoperative infection compared with absence of a bone graft.

Effect of the sonic hedgehog inhibitor GDC-0449 on an in vitro isogenic cellular model simulating odontogenic keratocysts

Odontogenic keratocysts (OKCs) are common cystic lesions of odontogenic epithelial origin that can occur sporadically or in association with naevoid basal cell carcinoma syndrome (NBCCS). OKCs are locally aggressive, cause marked destruction of the jaw bones and have a propensity to recur. PTCH1 mutations (at ∼80%) are frequently detected in the epithelia of both NBCCS-related and sporadic OKCs, suggesting that PTCH1 inactivation might constitutively activate sonic hedgehog (SHH) signalling and play a major role in disease pathogenesis. Thus, small molecule inhibitors of SHH signalling might represent a new treatment strategy for OKCs. However, studies on the molecular mechanisms associated with OKCs have been hampered by limited epithelial cell yields during OKC explant culture. Here, we constructed an isogenic PTCH1^R135X/+ cellular model of PTCH1 inactivation by introducing a heterozygous mutation, namely, c.403C>T (p.R135X), which has been identified in OKC patients, into a human embryonic stem cell line using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system. This was followed by the induction of epithelial differentiation. Using this in vitro isogenic cellular model, we verified that the PTCH1^R135X/+ heterozygous mutation causes ligand-independent activation of SHH signalling due to PTCH1 haploinsufficiency. This activation was found to be downregulated in a dose-dependent manner by the SHH pathway inhibitor GDC-0449. In addition, through inhibition of activated SHH signalling, the enhanced proliferation observed in these induced cells was suppressed, suggesting that GDC-0449 might represent an effective inhibitor of the SHH pathway for use during OKC treatment.

Using gene-edited cell cultures, Chinese researchers have gathered useful insights into the genetic origins and treatment of benign oral tumours called odontogenic keratocysts (OKCs). A total of 80% of OKCs are associated with mutations in the gene PTCH1, which are thought to activate a signalling pathway that drives OKC tumour growth. However, research is hindered by OKC cell culturing limitations. Tiejun Li, from the Peking University School and Hospital of Stomatology, and colleagues created an OKC cell culture model that uses CRISPR gene editing to introduce a PTCH1 gene mutation into human stem cells before differentiating them into epithelial cells. Using their model, the team confirm that PTCH1 mutation activates tumour-associated signalling, which the basal cell carcinoma drug vismodegib greatly reduces. Vismodegib also reduces the overproliferation of mutant cells and offers a potential treatment option for OKC patients.

Odontogenic Keratocyst: Developing a Protocol for Surgical Intervention

The aim of this study was to report the outcome of a conservative treatment protocol – “enucleation and packing open” for odontogenic keratocyst (OKC). Ten patients with OKC were treated at our institute by peripheral ostectomy, enucleation followed by open packing. This conservative treatment protocol was selected because of relatively young age of the patients and relatively large size of the lesions. All the cases were monitored at regular predetermined intervals using clinical evaluation and panoramic radiographs. There was no evidence of recurrence during follow-up. The conservative treatment protocol for OKC, based on enucleation followed by open packing would be a possible choice in view of the simplicity of surgical procedure and low morbidity. This treatment modality has a low recurrence rate and may be particularly useful in young patients and patients with advanced systemic disease not amenable to major surgical intervention.