Clinical relevance of cone beam computed tomography in mandibular third molar removal: A multicentre, randomised, controlled trial

PURPOSE

The aims of this study were to investigate the effectiveness of cone beam computed tomography (CBCT) compared to panoramic radiography (PR), prior to mandibular third molar removal, in reducing patient morbidity, and to identify risk factors associated with inferior alveolar nerve (IAN) injury.

MATERIAL AND METHODS

This multicentre, randomised, controlled trial was performed at three centres in the Netherlands. Adults with an increased risk for IAN injury, as diagnosed from PR, were included in the study. In one arm of the study, patients underwent an additional CBCT prior to third molar surgery. In a second arm of the study, no additional radiographs were acquired. The primary outcome measure was the number of patient-reported altered sensations 1 week after surgery. As secondary outcome measures, the number of patients with objective IAN injury, with long-term (>6 months) IAN injury, the occurrence of other postoperative complications, the Oral Health Related Quality of Life-14 (OHIP-14) questionnaire responses, postoperative pain (visual analogue scale score), duration of surgery, number of emergency visits, and number of missed days of work or study were scored.

RESULTS

A total of 268 patients with 320 mandibular third molars were analysed according to the intention-to-treat principle. The overall incidence of IAN injury 1 week after surgery was 6.3%. No significant differences between CBCT and PR for temporary IAN injury (p = 0.64) and all other secondary outcomes were registered. A lingual position of the mandibular canal (MC) and narrowing, in which the diameter of the MC lumen was decreased at the contact area between the MC and the roots, were significant risk factors for temporary IAN injury.

CONCLUSION

Although CBCT is a valuable diagnostic adjunct for identification of an increased risk for IAN injury, the use of CBCT does not translate into a reduction of IAN injury and other postoperative complications, after removal of the complete mandibular third molar. In these selected cases of a high risk for IAN injury, an alternative strategy, such as monitoring or a coronectomy, might be more appropriate. (http://clinicaltrials.gov, NCT02071030).

Evaluation of the anterior mandibular donor site one year after secondary reconstruction of an alveolar cleft: 3-dimensional analysis using cone-beam computed tomography

The aim of this study was to analyse changes in the volume of the chin after harvest of a bone graft for secondary reconstruction of an alveolar cleft. Cone-beam computed tomographic (CT) scans of 27 patients taken preoperatively, and immediately and one year postoperatively, were analysed, and 3-dimensional hard-tissue reconstructions made. The hard-tissue segmentation of the scan taken one year postoperatively was subtracted from the segmentation of the preoperative scan to calculate the alteration in the volume of bone at the donor site (chin). A centrally-orientated persistent concavity at the buccal side of the chin was found (mean (range) 160 (0-500) mm(3)). At the lingual side of the chin, a central concavity remained (mean (range) volume 20 (0-80) mm(3)). Remarkably, at the periphery of this concavity there was overgrowth of new bone (mean (range) volume 350 (0-1600) mm(3)). Re-attachment of the muscles of the tongue resulted in a significantly larger central lingual defect one year postoperatively (p=0.01). We also measured minor alterations in volume of the chin at one year. Whether these alterations influence facial appearance and long term bony quality is to be the subject of further research.

Diagnostic Performance of ¹⁸F-FDG PET and PET/CT for the Detection of Recurrent Esophageal Cancer After Treatment with Curative Intent: A Systematic Review and Meta-Analysis

The aim of this study was to assess the diagnostic performance of (18)F-FDG PET and integrated (18)F-FDG PET/CT for diagnosing recurrent esophageal cancer after initial treatment with curative intent.

METHODS

The PubMed, Embase, and Cochrane library were systematically searched for all relevant literature using the key words "(18)F-FDG PET" and "esophageal cancer" and synonyms. Studies examining the diagnostic value of (18)F-FDG PET or integrated (18)F-FDG PET/CT, either in routine clinical follow-up or in symptomatic patients in whom recurrence of esophageal cancer was suspected, were deemed eligible for inclusion. The primary outcome was the presence of recurrent esophageal cancer as determined by histopathologic biopsy or clinical follow-up. Risk of bias and applicability concerns were assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Sensitivities and specificities of individual studies were meta-analyzed using bivariate random-effects models.

RESULTS

Eight eligible studies were included for meta-analysis, comprising 486 patients with esophageal cancer who underwent (18)F-FDG PET or PET/CT after previous treatment with curative intent. The quality of the included studies assessed by the QUADAS-2 tool was considered reasonable; there were few concerns with regard to the risk of bias and applicability. Integrated (18)F-FDG PET/CT and standalone (18)F-FDG PET were used in 4 and 3 studies, respectively. One other study analyzed both modalities separately. In 4 studies, (18)F-FDG PET or PET/CT was performed as part of routine follow-up, whereas in 4 other studies the diagnostic test was performed on indication during clinical follow-up. Pooled estimates of sensitivity and specificity for (18)F-FDG PET and PET/CT in diagnosing recurrent esophageal cancer were 96% (95% confidence interval, 93%-97%) and 78% (95% confidence interval, 66%-86%), respectively. Subgroup analysis revealed no statistically significant difference in diagnostic accuracy according to type of PET scanner (standalone PET vs. integrated PET/CT) or indication of scanning (routine follow-up vs. on indication).

CONCLUSION

(18)F-FDG PET and PET/CT are reliable imaging modalities with a high sensitivity and moderate specificity for detecting recurrent esophageal cancer after treatment with curative intent. The use of (18)F-FDG PET or PET/CT particularly allows for a minimal false-negative rate. However, histopathologic confirmation of (18)F-FDG PET- or PET/CT-suspected lesions remains required, because a considerable false-positive rate is noticed.

An Accuracy Study of Computer-Planned Implant Placement in the Augmented Maxilla Using Mucosa-Supported Surgical Templates

PURPOSE

The purpose of this study was to determine the clinically relevant accuracy of implant placement in the augmented maxilla using computer planning and a mucosa-supported surgical template.

MATERIALS AND METHODS

Twenty-five consecutive edentulous patients with an extreme maxillar alveolar ridge resorption were treated with a bone augmentation procedure. In a second stage, six Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants were installed. Preoperatively, a cone beam computer tomography (CBCT) scan was acquired, followed by virtual implant planning and flapless implant placement using a surgical template. A postoperative CBCT scan was acquired and registered to the preoperative scan. The Implant Position Orthogonal Projection validation method was applied to measure implant deviations in both the buccolingual and mesio-distal plane. The influence of fixation pins and the position on the dental arch were investigated with regard to implant deviations, and rotations and translations of the surgical template.

RESULTS

One hundred fifty implants were installed. In mesio-distal direction, a mean implant deviation of 1.50 mm was scored at the implant tip, 1.27 mm at the shoulder, -0.60 mm in depth, as well as a mean deviation of angulation of 2.50°. In buccolingual direction, a mean implant deviation of 0.99 mm was found at the implant tip, 0.76 mm at the implant shoulder, -0.57 mm in depth, and a deviation of angulation of 2.48°. Of all implants, 53% was placed too superficial compared with the planning. The use of fixation pins and implant deviations in both buccal and mesial directions as also for rotations and translation of the surgical template showed statistically significant differences.

CONCLUSIONS

Computer-aided implant planning showed to be a clinically relevant tool. However, this study emphasizes that the surgeon should take into account that deviations are larger compared with implant placement without augmentation procedure. Deviations are mainly caused by angulations and translations of the surgical template.

Lower border bone onlays to augment the severely atrophic (class VI) mandible in preparation for implants: a preliminary report

We present the preliminary results of a study involving a group of consecutive patients who underwent lower border onlay grafting, limited to the symphyseal area, in preparation for implant insertion. This technique allows for maximum-sized implants, followed by prosthetic rehabilitation. The main advantage of this method is the minimal risk of damage to the mental nerve. Sixteen patients were followed for a period of 6 months to 4 years and all were free of neurosensory disturbances. Eight had a removable overdenture placed and were satisfied with the result. This surgical approach allows the patient to wear their dentures during the healing period. A further advantage of lower border grafting over intraoral upper border grafting is that mucosal dehiscences are not seen.

Intraoral-extraoral combination prosthesis: improving retention using interconnecting magnets

Osseointegrated implants have been well documented for retaining an obturator prosthesis as well as a facial prosthesis. However, when the defect extends to both the facial area and the maxilla, it is difficult to rehabilitate those defects to the satisfaction of the patient, especially in cases where implants cannot be placed on both sites. This case report describes the use of magnets to connect two prostheses, thereby increasing retention and patient comfort.

[Incisors with a mind of their own]

A 43-year-old man, known to have hypodontia, was bothered by his over-erupted central incisors. After the placement of implants and the accompanying crown- and bridgework, the central incisors appear to be increasingly over-erupted. The history shows that this phenomenon has already been seen in the past. Three mechanisms can be responsible for the over-eruption, specifically: continuous facial growth, over-eruption of both central incisors in the maxilla as a consequence of agenesis of opposing dentition and relapse of the orthodontic treatment as a result of the fact that orthodontic retention is not readily possible. After the central incisors were first cut in such a way that an acceptable incisal line has again been formed, the single-unit fixed dental prostheses on the front elements were replaced with porcelain ones.

[Lack of retention of the upper denture: is placement of 2 palatal implants the solution?]

A 72-year-old man, edentulous in the maxilla for 20 years, presented himself at his dentist in 2006 with complaints concerning retention of his upper denture. The placement of implants was only possible if bone augmentation was undertaken; this was definitively rejected by the man. As an alternative, Muchor anchors were placed, but these did not provide an adequate solution to the retention problem. In the end, 2 palatal implants were placed, with magnetic anchoring. One year later, the man was very satisfied with this solution.

Donor site complications in bone grafting: comparison of iliac crest, calvarial, and mandibular ramus bone

PURPOSE

To compare the donor site complication rate and length of hospital stay following the harvest of bone from the iliac crest, calvarium, or mandibular ramus.

MATERIALS AND METHODS

Ninety-nine consecutively treated patients were included in this retrospective observational single-center study.

RESULTS

Iliac crest bone was harvested in 55 patients, calvarial bone in 26 patients, and mandibular ramus bone in 18 patients. Harvesting of mandibular ramus bone was associated with the lowest percentages of major complications (5.6%), minor complications (22.2%), and total complications (27.8%). Harvesting of iliac crest bone was related to the highest percentages of minor complications (56.4%) and total complications (63.6%), whereas harvesting of calvarial bone induced the highest percentage of major complications (19.2%). The length of the hospital stay was significantly influenced by the choice of donor site (P = .003) and age (P = .009); young patients with the mandibular ramus as the donor site had the shortest hospital stay.

CONCLUSIONS

Harvesting of mandibular ramus bone was associated with the lowest percentage of complications and the shortest hospital stay. When the amount of bone to be obtained is deemed sufficient, mandibular ramus bone should be the first choice for the reconstruction of maxillofacial defects.

Quantification of esophageal tumor motion on cine-magnetic resonance imaging

PURPOSE

To quantify the movement of esophageal tumors noninvasively on cine-magnetic resonance imaging (MRI) by use of a semiautomatic method to visualize tumor movement directly throughout multiple breathing cycles.

METHODS AND MATERIALS

Thirty-six patients with esophageal tumors underwent MRI. Tumors were located in the upper (8), middle (7), and lower (21) esophagus. Cine-MR images were collected in the coronal and sagittal plane during 60 seconds at a rate of 2 Hz. An adaptive correlation filter was used to automatically track a previously marked reference point. Tumor movement was measured in the craniocaudal (CC), left-right (LR), and anteroposterior (AP) directions and its relationship along the longitudinal axis of the esophagus was investigated.

RESULTS

Tumor registration within the individual images was typically done at a millisecond time scale. The mean (SD) peak-to-peak displacements in the CC, AP, and LR directions were 13.3 (5.2) mm, 4.9 (2.5) mm, and 2.7 (1.2) mm, respectively. The bandwidth to cover 95% of excursions from the mean position (c95) was also calculated to exclude outliers caused by sporadic movements. The mean (SD) c95 values were 10.1 (3.8) mm, 3.7 (1.9) mm, and 2.0 (0.9) mm in the CC, AP, and LR dimensions. The end-exhale phase provided a stable position in the respiratory cycle, compared with more variety in the end-inhale phase. Furthermore, lower tumors showed more movement than did higher tumors in the CC and AP directions.

CONCLUSIONS

Intrafraction tumor movement was highly variable between patients. Tumor position proved the most stable during the respiratory cycle in the end-exhale phase. A better understanding of tumor motion makes it possible to individualize radiation delivery strategies accordingly. Cine-MRI is a successful noninvasive modality to analyze motion for this purpose in the future.

Concise review: cell-based strategies in bone tissue engineering and regenerative medicine

Cellular strategies play an important role in bone tissue engineering and regenerative medicine (BTE/RM). Variability in cell culture procedures (e.g., cell types, cell isolation and expansion, cell seeding methods, and preculture conditions before in vivo implantation) may influence experimental outcome. Meanwhile, outcomes from initial clinical trials are far behind those of animal studies, which is suggested to be related to insufficient nutrient and oxygen supply inside the BTE/RM constructs as some complex clinical implementations require bone regeneration in too large a quantity. Coculture strategies, in which angiogenic cells are introduced into osteogenic cell cultures, might provide a solution for improving vascularization and hence increasing bone formation for cell-based constructs. So far, preclinical studies have demonstrated that cell-based tissue-engineered constructs generally induce more bone formation compared with acellular constructs. Further, cocultures have been shown to enhance vascularization and bone formation compared with monocultures. However, translational efficacy from animal studies to clinical use requires improvement, and the role implanted cells play in clinical bone regeneration needs to be further elucidated. In view of this, the present review provides an overview of the critical procedures during in vitro and in vivo phases for cell-based strategies (both monoculture and coculture) in BTE/RM to achieve more standardized culture conditions for future studies, and hence enhance bone formation.

A clinically relevant accuracy study of computer-planned implant placement in the edentulous maxilla using mucosa-supported surgical templates

PURPOSE

The purpose of the study is to determine the clinically relevant accuracy of implant placement in the edentulous maxilla using computer planning and a mucosa-supported surgical template.

MATERIALS AND METHODS

In each of in total 30 consecutive edentulous patients suffering from retention problems of their upper denture, two or four Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants in the maxilla were installed. Preoperatively, first, a cone-beam computer tomography (cone beam computer tomography) scan was acquired, followed by virtual implant planning. Hereafter, a surgical template was designed to allow flapless implant placement using the template as a guide. To inventory the accuracy of implant placement, a postoperative CBCT scan was obtained and matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally. The Implant Position Orthogonal Projection validation method was applied to measure the clinically relevant implant deviations (i.e., in both the bucco-lingual and mesio-distal plane). Also, the influence of type of surgery, use of fixation pins, and position on the dental arch were investigated with regard to implant deviations.

RESULTS

In total, 104 implants were installed. In bucco-lingual direction, a mean implant deviation of 0.67 mm was scored at the implant tip, of 0.51 mm at the shoulder, of -0.83 mm in depth, as also a mean deviation of angulation of 1.74°. In mesio-distal direction, a mean implant deviation of 0.75 mm was found at the implant tip, of 0.60 mm at the implant shoulder, of -0.75 mm in depth, and a deviation of angulation of 1.94°. Of all implants, 74% was placed not deep enough compared with the planning. Implant position on the dental arch, the use of fixation pins, and type of surgery showed no significant effect on implant deviations. However, a significant difference for implant deviations in both buccal and mesial direction was observed, explained by a nonoptimal positioning of the surgical template.

CONCLUSIONS

Computer-aided implant planning showed to be a clinically relevant tool for the placement of two or four implants in the maxilla of fully edentulous patients. Exact positioning of the surgical template in anterior/posterior direction is crucial in reducing implant deviations both in buccal and mesial direction.

The in vivo performance of CaP/PLGA composites with varied PLGA microsphere sizes and inorganic compositions

Enrichment of calcium phosphate (CaP) bone substitutes with poly(lactic-co-glycolic acid) (PLGA) microspheres to create porosity overcomes the problem of poor CaP degradation. The degradation of CaP-PLGA composites can be customized by changing the physical and chemical properties of PLGA and/or CaP. However, the effect of the size of dense (solid rather than hollow) PLGA microspheres in CaP has not previously been described. The present study aimed at determining the effect of different dense (i.e. solid) PLGA microsphere sizes (small (S) ~20μm vs. large (L) ~130μm) and of CaP composition (CaP with either anhydrous dicalcium phosphate (DCP) or calcium sulphate dihydrate (CSD)) on CaP scaffold biodegradability and subsequent bone in-growth. To this end mandibular defects in minipigs were filled with pre-set CaP-PLGA implants, with autologous bone being used as a control. After 4weeks the autologous bone group outperformed all CaP-PLGA groups in terms of the amount of bone present at the defect site. On the other hand, at 12weeks substantial bone formation was observed for all CaP-PLGA groups (ranging from 47±25% to 62±15%), showing equal amounts of bone compared with the autologous bone group (82±9%), except for CaP with DCP and large PLGA microspheres (47±25%). It was concluded that in the current study design the difference in PLGA microsphere size and CaP composition led to similar results with respect to scaffold degradation and subsequent bone in-growth. Further, after 12weeks all CaP-PLGA composites proved to be effective for bone substitution.

A lower border augmentation technique to allow implant placement after a bilateral mandibular fracture as a complication of vertical distraction osteogenesis: a case report

As with other techniques, vertical distraction osteogenesis (VDO) can also induce complications. The case of a patient with a residual alveolar ridge in the symphyseal area of 8 mm is presented. After performing VDO, the patient returned at 1-day postoperatively complaining of pain and dislocation of the distractor device, due to a fracture of the lower mandibular segment on the right side. After removal of the distractor device and application of osteosynthesis plates, the patient returned 2 weeks later due to a second fracture of the lower segment, yet on the left side. After removing the osteosynthesis material, stabilization of the mandible was achieved with an acrylic splint, which was fixated with peri-mandibular wiring. Finally, reconstruction was accomplished by lower border onlay grafting, limited to the symphyseal area, in preparation for implant insertion. Ultimately, after a healing period of 5 months, two endosseous implants were installed. The patient's function has remained satisfactory for 3 years. Reinforcement of the extreme resorbed edentulous mandible after fracture healing by lower border bone augmentation can be a reliable method to allow implant installation in a second stage.

[The impact of dental implants]

The importance of the introduction of dental implants can only be understood when the historical context is clarified. In the past, the main treatment carried out by dentists consisted of filling or, in unfortunate cases, removal of painful teeth. Only since the introduction of dental implants did it become feasible to restore dental arches in edentulous patients with complaints about their freestanding prostheses. Initially much scepticism prevailed about dental implants. When titanium with a roughened surface is used, implant success rises above 95%, provided that the implants are placed into sufficient bone volume.

A clinically relevant validation method for implant placement after virtual planning

PURPOSE

To design a relevant method to compare the virtual planned implant position to the ultimately achieved implant position and to evaluate, in case of discrepancy, the cause for this.

MATERIALS AND METHODS

Five consecutive edentulous patients with retention problems of the upper denture received four implants in the maxilla. Preoperatively, first a cone-beam CT (CBCT) scan was acquired, followed by virtual implant planning. Then, a surgical template was designed and endosseous implants were flapless installed using the template as a guide. To inventory any differences in position, the postoperative CBCT scan was matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally (3D) and the Implant Position Orthogonal Projection (IPOP) validation method was applied to project the results to a bucco-lingual and mesio-distal plane. Subsequently, errors introduced by virtual planning, surgical instruments, and validation process were evaluated.

RESULTS

The bucco-lingual deviations were less obvious than mesio-distal deviations. A maximum linear tip deviation of 2.84 mm, shoulder deviation of 2.42 mm, and angular deviation of 3.41° were calculated in mesio-distal direction. Deviations included errors in planning software (maximum 0.15 mm), for surgical procedure (maximum 2.94°), and validation process (maximum 0.10 mm).

CONCLUSIONS

This study provides the IPOP validation method as an accurate method to evaluate implant positions and to elucidate inaccuracies in virtual implant planning systems.

Soft tissue response to zirconia and titanium implant abutments: an in vivo within-subject comparison

AIM

To compare the health of the soft tissues towards zirconia and titanium abutments in man, as observed using histological data.

MATERIAL AND METHODS

Twenty patients received two mandibular implants with either a zirconia or titanium abutment (split mouth study design, left-right randomization). After 3 months soft tissue biopsies were prepared for histological evaluation. They were subjected to blind evaluation. The number of blood vessels per surface unit and an inflammation grading scale score ranging from 1 to 4 were determined.

RESULTS

Paired samples from 17 patients were suitable for analysis, 3 with unsevered implant-abutment connections and 14 solely containing soft tissue. All showed a well-keratinized stratified squamous epithelium which was continuous with the barrier (junctional) epithelium that faced the abutment surface. The normal epithelial build-up could be recognized with little signs of inflammation. No statistically significant difference in tissues adjacent to zirconia and titanium abutment surfaces were seen with respect to vascular density (20.5 SD 4.4 and 20.7 SD 3.2) or inflammation grading scale scores (3.2 SD 0.7 versus 3.1 SD 0.7).

CONCLUSION

No differences in soft tissue health were seen in peri-implant mucosa adjacent to zirconia and titanium abutment surfaces.