How reliable are follow-up studies on odontogenic keratocysts?

Follow-up studies on odontogenic keratocysts have reported widely varying recurrence rates. This raises the question of how reliable these studies are and how the results should be interpreted. The aim of this study was to critically assess the information from all follow-up studies published since 2004 against a set of criteria to determine how thorough the study was. These criteria include the exclusion of the orthokeratinized variant, exclusion of cysts associated with nevoid basal cell carcinoma syndrome, and appropriate reporting of dropouts. A search of four electronic databases covering the years 2004-2022 was performed. Only studies with a sufficient follow-up period (covering a range of 1-8 years) were included. Studies with fewer than 40 cases were excluded. Fourteen relevant studies were identified in the literature search. The vast majority of these studies had considerable shortcomings, giving rise to serious doubts about the validity of their recurrence rate results. Of note, these studies have often been included in meta-analyses that report on the best treatment options to reduce the tendency of recurrences. The results of this review strongly suggest that multicentre studies with strict protocols should be performed to advance knowledge of the presentation of recurrences, both the timing and frequency.

The odontogenic keratocyst revisited.

The treatment of odontogenic keratocysts is reviewed in light of the aetiology and pathogenesis of these lesions. The role of the dental lamina and submucosal hamartias, as frequently seen in nevoid basal cell carcinoma syndrome, is discussed, and the implications for treatment are emphasized.

The significance of recurrent odontogenic keratocysts in bone grafts.

A comprehensive literature review identified 10 reported cases of recurrent odontogenic keratocysts (OKCs) in bone grafts. Seven of them were sufficiently documented for further analysis. All except one of the patients had a long history of repeated recurrences. They were all approached via an extraoral route, avoiding a mucosal perforation, when the bone graft was placed after a segmental resection. In three cases, this was also true for the primary treatment. The origin of the recurrences is considered to be the oral mucosa, almost certainly involving the proliferation of epithelial islands or microcysts that were close to the original OKC. A plea is made to avoid segmental or marginal resections for this lesion and to pay attention to possible epithelial islands/microcysts in the overlying attached mucosa in the case where marsupialization is preferred.

Graeme Warrack: oral surgeon and war hero.

This paper describes the heroic efforts of Graeme Warrack, an oral surgeon, to save as many lives as possible during the battles around Arnhem in 1944. As the chief medical officer (CMO) of the medical section of the 1st British Airborne Division, he and his staff took care of many casualties, both on the battlefield and at the emergency hospital in Apeldoorn, north of Arnhem. He escaped from the hospital when all the patients were to be transported to prisoner of war (POW) camps in Germany, and was hidden by a Dutch family. Finally, with the help of the Dutch resistance movement, he was successfully ferried over the big rivers into liberated country.

Modular endoprosthesis for mandibular body reconstruction: a clinical, micro-CT and histologic evaluation in eight Macaca fascicularis.

This paper presents the results of an animal experiment, in which a modular endoprosthesis is tested to replace a resected part of the mandible. The prostheses were fixed with polymethacrylate (PMMA) cement into the medullar space of the stumps. Clinical, radiologic, micro-computed tomographic and histologic evaluations were made after 3 and 6 months on four Macaca fascicularis for each implantation time. The prosthesis had not loosened but there were some loose screws that had caused fistulas in three animals. The stems of the modules were stably fixed with PMMA cement, surrounded by a fibrous capsule with inflammatory cells. This capsule was thinner in the 6-month group and showed less inflammatory infiltrate compared with the 3-month group; this was not statistically significant. There was an increase in woven bone surrounding the modules after 6 months. After 3 months of implantation, there was a considerable inflammatory reaction in the soft tissues surrounding the module, which subsided over following 3 months. The results are encouraging, but a longer period of follow-up is required to assess its application in a clinical setting, and some design drawbacks need to be addressed.

[Complications and failures in dentoalveolar surgery]. / Complicaties en mislukkingen in de dentoalveolaire chirurgie.

Complications and failures are unavoidable in dentoalveolar surgery, but can be reduced if treatment is carried out in the proper manner. Yet, one has to accept a certain percentage of complications and failures and the patient should be informed about that prior to surgery. Complications become reproachable when insufficient diagnostic procedures have been carried out or when surgery has not been performed in the proper fashion. Insufficient prior information, even in cases of referral, must be seen as reproachable practice, especially in the context of the Law on Medical Treatment Agreement.

Modular endoprosthesis for mandibular reconstruction: a preliminary animal study.

The use of a mandibular modular endoprosthesis after segmental resection of part of the body of the mandible was studied. This preliminary study was carried out on four pigs and four monkeys. The devices were made of a titanium alloy and were cemented in the prepared medullary spaces with polymethylmetacrylate cement. The prosthesis failed in one pig, but in the other animals the prostheses were stable and firmly fixed to the stumps after 3 months. It was concluded that the endoprosthesis has potential in reconstructive surgery of the mandible, but that further studies are necessary to substantiate this claim. Pigs are not suitable for further studies as the medullary space is too large and filled with fat. They are also too big to handle and the variations in size and shape of the mandibles precludes the use of a modular system.

What is the quality of the evidence base for pre-implant surgery of the atrophic jaw?

This review aimed to evaluate the level of evidence for bone augmentation preimplant surgery for atrophic jaws in studies which measure outcome. Medline, Embase, Cochrane library and online journal searches were performed with a defined search strategy and the abstracts screened against selection criteria. The resultant papers were sorted by study design using the Cochrane study design algorithm, analysed for clinical/statistical homogeneity and graded with the Oxford Centre of Evidence-based Medicine levels of evidence. The initial online Medline search yielded 1194 results and the Embase search yielded 490 results. Using the selection criteria, 10 studies were identified. Additionally, 5 articles were identified from bibliography and online searches, giving a total of 15 studies for grading. All 15 studies were graded as level 4 evidence. No meta-analysis of outcomes was possible with the low level of evidence and degree of heterogeneity found. The best grade of recommendation that can be made for a particular preimplant surgical bone augmentation procedure, from these level 4 studies, is Grade C. Benchmarking studies by assessing quality of evidence can be helpful to inform future study designs with respect to reporting study outcomes with a higher level of evidence.

Orthotopic bone formation in titanium fiber mesh loaded with platelet-rich plasma and placed in segmental defects.

The effect of platelet-rich plasma (PRP) on bone formation was investigated in a rabbit segmental radial defect model. The purpose of the study was to evaluate the bone inductive properties of PRP with titanium fiber mesh and autologous bone chips in a 15-mm rabbit radial defect model. Eighteen New Zealand white rabbits were divided into three groups: I, PRP with autologous bone (PRP-Ti-Bone); II, autologous bone (Ti-Bone); III, control group (Ti). The implants were placed in the radial defect for 12 weeks. After sacrifice, all specimens were harvested for histological, histomorphometrical and radiographic analysis. Histomorphometrical analysis showed that bone formation was higher in the implants with PRP (PRP-Ti-Bone: 37+/-8%) than in those without PRP (Ti-bone: 25+/-6% and Ti: 25+/-5%) after 12 weeks of implantation. It was concluded that PRP has a stimulatory effect on bone formation in titanium fiber mesh filled with autologous bone graft in segmental bone defects. Titanium fiber mesh was also shown to be an excellent scaffold material for the application of autologous bone grafts with or without PRP.

Assessment of mandibular invasion of squamous cell carcinoma by various modes of imaging: constructing a diagnostic algorithm.

The aim of this study was to determine the optimal combination of preoperative examination methods to predict mandibular invasion by squamous cell carcinoma of the oral cavity. Data were gathered prospectively but evaluated retrospectively. The preoperative results of clinical examination, conventional radiography, bone single photon emission computed tomography (SPECT), computed tomography and magnetic resonance imaging were compared to the histological results of resection specimens from 67 patients with tumours, adjacent or fixed to the mandible, histologically confirmed as squamous cell carcinoma. The examination methods with acceptable sensitivity and specificity were selected and diagnostic algorithms were constructed using all possible combinations. The preferred diagnostic algorithm was found to be either computed tomography or magnetic resonance imaging, followed by a bone SPECT in cases where the first scan is negative. A negative bone SPECT rules out mandibular invasion (100% sensitivity). This algorithm accurately predicted mandibular invasion in 85% of the patients, without yielding false negative results. In this study group, application of such an algorithm would have resulted in a reduction of the number of unnecessary mandibular resections by 50%. The suggested, preferred, diagnostic algorithm shortens the preoperative screening process, avoiding unnecessary costs, as well as considerably reducing the number of unnecessary mandibular resections.

The reliability of frontal facial photographs to assess changes in nasolabial soft tissues.

A simple, modified method to evaluate changes in the nasolabial soft tissues after orthognathic surgery is presented. Eighteen healthy volunteers were photographed in a standardized manner with a 2-month interval. Pictures were taken with the soft tissues in repose and 'maximum closed mouth smile'. Discrepancies for repose and dynamic excursions (x and y coordinates) were calculated for the landmarks alare, crista philtri and cheilion. Multiple analysis of variance revealed no significant interaction for intra-observer variance and time of recording. Coefficients of reliability (repose: 90-99%, dynamic excursion (cheilion): >95%), Spearman correlation coefficients (repose: >0.8, dynamic: >0.6) and squared correlation (repose: >75%, dynamic: >50%) showed this method to be reliable for repose and dynamic excursions. The error of measurement was less than 1.8 mm for both repose and dynamic excursions (SD(differences)=0.9 mm). This is smaller than mean differences in nasolabial soft-tissues excursions found between the pre- and post-Le Fort I osteotomy situation in a previous study using video imaging. The discrepancies found were in keeping with other earlier reports for 2D and 3D measuring methods. The method as proposed is simple, cost effective and can be used to evaluate soft-tissue changes after orthognathic surgery.

Long-term evaluation of bilateral cleft lip and palate patients after early secondary closure and premaxilla repositioning.

The aim of this retrospective, mixed longitudinal study was to assess the long-term outcome of early secondary closure and premaxilla osteotomy in 40 bilateral cleft lip and palate patients who underwent early secondary osteotomy of the premaxilla and bone grafting at the age of 8-12 years. Clinical and cephalometric evaluations of profile, lip relation, nasolabial angle and position of the maxilla preoperatively, postoperatively and at adolescence were compared to normal values of non-cleft individuals and the reported data of 90 bilateral cleft lip and palate patients treated in Oslo. In 68% of patients the profile was considered acceptable, but in 26 maxillary growth appeared to be impaired by cephalometric standards. In four patients a Le Fort I osteotomy was carried out and nine patients would have benefited from such a procedure. This study reveals a trend towards maxillary growth retardation partially compensated by orthodontic and dental treatment. Since the results are comparable to those reported for the Oslo group with regard to maxillary growth, the surgical protocol followed does not require revision. Considering the benefits, i.e. closure of alveolo-palatal cleft, continuity of dental arch, eruption of canine in the graft and closure of oro-nasal communications, this mode of treatment should be continued.

The effect of platelet-rich plasma on early and late bone healing: an experimental study in goats.

Four round critical-size defects were made in the foreheads of 20 goats. The defects were filled with autogenous particulate cancellous bone, in which 1 ml of platelet-rich plasma (PRP) was added in two of the four defects of each goat. The goats were divided into four subgroups of five goats each, which were killed after 1, 2, 6 and 12 weeks. The results of histologic and histomorphometric examination showed that early and late bone healing was not enhanced when PRP was used.

Reconstruction of the mandible after ablative surgery for the treatment of aggressive, benign odontogenic tumours in Tanzania: a preliminary study.

This study presents results on 11 patients suffering from ameloblastoma who had ablative surgery followed by reconstruction of the mandible in a single operative procedure in Tanzania. The procedure included the use of autogenous particulate bone from the anterior or posterior iliac crest. In 6 of the patients, the tumour was removed from the cortical scaffold, which was then irradiated with 50 Gy. Perforations were made on the scaffold and it was then placed back to fit the defect and was held in place by custom-made titanium plates, fixed on both ends with screws. The particulate bone chips were mixed with autogenous platelet rich plasma (PRP) and Tissue Col. In 5 of the patients, the cortical scaffold was not used but rather a mixture of bone and PRP was packed into the defect under the titanium plates. Four patients had some complications varying from fracture of the scaffolds to infection. None from the group reconstructed without scaffolds suffered any complications. A quality of life (QOL) assessment of the 7 successful cases showed that these patients were satisfied and had a good QOL. These results imply that this immediate means of reconstruction is feasible and thus, offers a big advantage to the patients.

Reconstruction of the mandible with an autogenous irradiated cortical scaffold, autogenous corticocancellous bone-graft and autogenous platelet-rich-plasma: an animal experiment.

This paper reports on an experimental animal study evaluating a method of mandibular reconstruction using irradiated cortical scaffolds. Twelve goats underwent a continuity resection at the mandibular angle. Primary reconstruction was carried out using specially designed osteosynthesis plates and screws. The defect was bridged by the original, irradiated cortical scaffold, which was filled with an autogenous particulate bone graft from the anterior iliac crest. To accelerate bone healing, platelet rich plasma (PRP) was mixed with the particulate bone graft. The hypothesis of this study was that bone healing in segmental reconstruction of the goat mandible by means of an irradiated cortical scaffold, filled with a particulate cancellous bone graft mixed with PRP, would be as successful as when using a non-irradiated scaffold. All goats had an uneventful healing. The osteosynthesis plates and screws withstood immediate loading for periods varying from three to six weeks. The radiologic and histologic results were less favourable with regard to bone remodelling than the results obtained in similar experiments with non-irradiated cortical bone scaffolds.

Stabilisation of sagittal split set-back osteotomies with miniplates: a prospective, multicentre study with 2-year follow-up.

The aim of this study was to assess post-operative stability of bilateral sagittal split set-back osteotomies using two miniplates and clinical parameters including nerve function, TMJ function, occlusal relapse and patient satisfaction. The stability was measured on cephalometric radiographs and possible condylar alterations on orthopantomograms. This prospective study implied a 2-year follow-up on a group of 24 patients. The same protocol was used at six participating institutions at which the patients were treated. A stable occlusion without appreciable relapse was seen in 91% after 2-year follow-up. Only two patients in this study had mild occlusal relapse. The mean skeletal horizontal relapse at pogonion of the whole group, after 2 years was 1.1mm and appeared to be directed backwards. At occlusal level, however, the mean relapse was 1.2mm forwards. The function of the inferior alveolar nerve 2 years post-operatively was reported to be normal in approximately 70% of the patients, yet 80% had no complaints about nerve dysaesthesia. In approximately 21% of the patients, signs and symptoms of TMJ dysfunction had disappeared. Another group (10%), however, without pre-operative signs and symptoms of TMJ dysfunction developed these signs or symptoms post-operatively. No condylar remodelling or resorption was seen in this group of patients. The sagittal split set-back osteotomy fixed with miniplates appeared to be a relatively save and reliable procedure giving rise to adequate results and a high degree of patients satisfaction.

Evaluation of quality of life among patients after extirpation of mandibular ameloblastoma.

OBJECTIVE: To evaluate the quality of life (QOL) based on the functional, aesthetic and personal satisfaction among patients with ameloblastoma who underwent either partial or total mandibulectomy without reconstruction. DESIGN: Cross-sectional study. SETTING: The Department of Oral Surgery and Oral Pathology, School of Dentistry; Muhimbili University College of Health Sciences, Tanzania. SUBJECTS: Patients surgically treated for ameloblastoma without reconstruction. RESULTS. The postoperative problems were mostly associated with eating of solid foods, appearance and speech. All patients treated by total mandibulectomy had moderately severe problems with eating of solid foods and were dissatisfied with their appearance. CONCLUSION: The relatively small tumours resulted in a much better QOL. Public awareness programmes to avoid late referral and treatment is the most effective way to reduce the number of patients who after treatment suffer a poor QOL.

[Use of bone grafts from the mandibular body in pre-implant surgery]. / Toepassing van bottransplantaten uit het corpus mandibulae voor preïmplantologische chirurgie.

Thirteen patients with resorption of the alveolar process in the upper or lower jaw were treated with augmentation using autogenous bone from the mandibular body. The objective and subjective results were retrospectively assessed. The morbidity of the donorsite was considered mild. 3 Patients experienced temporary sensory disturbance of the inferior alveolar nerve. In 1 patient spontaneous sequestration of a part of the transplant occured. In all patients the bonevolume at time of implantation was sufficient to insert the planned amount of implants. In total 46 implants were inserted. One implant was lost during follow-up and replaced. From this study it is concluded that the mandibular body can be considered as a good donor site for autogenous bone for pre-implant reconstruction of the alveolar process.