The aim of this study was to evaluate the final vertical gain at the deficient anterior maxillary alveolar ridges using onlay bone grafts with titanium mesh versus inlay bone grafting. This was a single institutional randomized comparative clinical trial. The study population included 16 patients, with edentulous anterior maxillary alveolar ridges (40 implant sites) who were presented and treated at the Faculty of Oral and Dental Medicine in Cairo University from September 2013 to August 2015. Selected patients were randomly divided into two equal groups. The control group received onlay particulate xenograft together with titanium mesh as a space-maintaining device while the study group received inlay block xenograft (sandwich osteotomy) fixed with mini-plates. Assessment using cone beam computed tomography (CBCT) included the mean percentage of vertical gain at the proposed implant sites after 6 months taken from cross-sectional cuts. A total of 40 delayed implant placements were done. Results showed that there was no statistical significance between the two groups ( P = 0.2); the mean percentage of 6 months postoperative vertical bone gain in the control group was 20.7% and that in the study group was 31.6%.
The problem of inadequate alveolar ridge height is a major limitation for successful placement of dental implants, where the routine techniques of implant placement are not possible because of the discrepancy between the available height of the ridge and that of the implant. For situations where the ridge height is marginal (i.e. < 10 mm or so), it is often possible to manage complications in osteotomy preparation such as bone fenestrations or dehiscence with various graft and barrier materials.
In more extreme cases, however it becomes necessary to prepare the deficient ridge with some form of ridge augmentation procedure, using, for example, either guided bone regeneration, vertical block grafting with autogenous bone, vertical distraction osteogenesis, and vertical reconstruction using titanium mesh with autogenous particulate bone grafts. These ridge augmentation procedures can increase the ridge vertical dimension but they will add extra expense, time, and morbidity of the donor. As an alternative to these approaches, some clinicians have proposed a variety of alveolar ridge vertical reconstruction techniques for treatment of vertical ridge deficiencies.
Inlay bone grafting and ridge reconstruction using titanium mesh have received growing acceptance and success as a vertical augmentation technique for maxillary bone. The resiliency and softness of the maxillary bone renders it possible for accepting the bone graft using titanium mesh and also mobilization in an occlusal direction during the inlay bone grafting procedure. Vertical bone gain remains the main challenge and restriction for the application of these techniques in the anterior aesthetic zone; thus, the aim of this study was to evaluate which technique will be more beneficial to the patient in terms of vertical bone gain.
Materials and methods
The investigators designed and implemented a single institutional double-blind randomized comparative clinical study. Patients suffering missing multiple maxillary anterior teeth were selected with deficient vertical bone height. After approval of the Ethics and Research Committee all patients were informed and consented to the procedures to be followed throughout the study ( Fig. 3 ).
To be included in the study sample, patients had to follow the following inclusion criteria: all patients were free from any systemic disease that may affect bone healing, no local pathosis that may interfere with bone healing, no history of any grafting procedure at the designated edentulous ridge.
Criteria of the edentulous ridge
The anterior maxillary vertical dimension was less than 10 mm, measured from the alveolar crest to the basal bone of the maxilla (i.e. the ridge had vertical inadequacy); the minimum number of missing teeth in the anterior maxillary alveolar ridges was two anterior teeth; the maximum was all six anteriors. There was increased interarch space compared with the adjacent teeth and the horizontal alveolar dimension was normal.
The patients were randomly divided into two equal (8 patients each) groups that underwent vertical ridge augmentation using either a particulate xenograft together with titanium mesh (control group) an inlay block xenograft fixed with mini-plates (study group). Randomization was carried out using appropriate computer software.
A thorough medical and dental history followed by clinical examination was carried out for all patients. Clinical measurements were taken to ensure patient adherence to our initial inclusion criteria prior to further investigations. Impressions were taken and a radio-opaque denture was fabricated to be used as a radiographic guide for standardizing the calculation of the final vertical ridge gain. The denture was fabricated using a radio-opaque material (barium sulphate mixed with acrylic in an 8:2 ratio), the radio-opaque teeth were used as a fixed reference to ensure that the measurements were done at the same area of interest: pre-, immediate, and 6 months postoperatively
Periapical radiographs were taken for primary investigation in order to exclude the presence of any lesion at the area of interest. A cone beam computed tomography (CBCT) scan was done as a final investigation for the assessment of the vertical dimension of the edentulous alveolar ridges. This vertical dimension of each implant site could be measured accurately in the reformatted cross sectional images ( Fig. 1 ).
Intraoperative surgical procedures: (both groups)
The local anaesthesia used was Scandonest 2% (each 1.8-ml cartridge contained 36 mg of mepivicaine hydrochloride with 18 mg of adrenaline (Septodent, Saint-Maur-des-Fossés, France)) for haemostasis.
Scrubbing and draping of the patient was carried out in a standard fashion using bitadine surgical scrub. A three-incision-line pyramidal flap was done by placing a crestal incision more to the palatal aspect of the crest of the ridge where the incision was cut between the two teeth that bounds the edentulous area. Two oblique releasing incisions were then cut at the distal ends of the crestal incision.
A full-thickness reflection of labial and palatal mucoperiosteal flap was performed. Reflection was extended to expose the whole length of the facial cortical plate of the alveolar ridge. In this group, bleeding points (decortication) were done using a rounded burr to expose the underlying marrow for easier graft consolidation, followed by application of the titanium mesh and the gap between it and the native bone was filled with particulate xenograft bone material (Tutogen, Neunkirchen am Brand, Germany; particle size 0.25–0.5 nm). Finally, the titanium mesh was fixed in place using three or four micro screws. Scouring was done to allow tension free closure using resorbable suturing material (vicryl 3-0) ( Figs. 2 and 3 ).
Only the labial flap was reflected leaving the palatal tissues without elevation as the mobilized bony segment will be pedicled on it ( Fig. 4 ). Three full-thickness cuts were performed. Two vertical stop cuts were made using a tungsten carbide disc at the distal ends of the midcrestal bony cut on the facial surface of alveolar ridge; the vertical cuts were 3 mm from the neighbouring teeth.
The above-described cuts were revised using ridge-splitting osteotomes (fine chisels) of sequential width (2 mm, 3 mm) and a lightweight mallet. The rectangular bony segment (transport segment) was finally mobilized occlusally and pedicled on the palatal mucoperiosteum ( Fig. 5 ). A block xenograft was snugly fitted between the mobilized segment and the basal bone, and finally the segment was fixed using mini-plates and mini-screws ( Fig. 6 ). Scoring was done to allow tension-free closure using resorbable suturing material (vicryl 3-0).
Data analysis and randomization
Patients were randomly divided into two equal groups using computer software; numbers were concealed by closed envelopes. Neither the patient nor the assessor was aware of the type of surgery done.
Study variables and measuring the final vertical gain for both groups (standardization of calculations)
The nasal floor was used as a fixed reference by adjusting the cross-sectional long axis in the centre of the area of interest and bisecting it (showing the buccolingual dimension). All the patients had worn the radiographic dentures with radio-opaque material (barium sulphate mixed with acrylic powder) filling the teeth at the area of interest, to ensure that the calculations were taken at the same region.
On the cross-sectional view of CBCT and at each proposed implant site, a line was drawn starting from the crest of the ridge till the apical level. The height was estimated preoperatively, immediately (1 week) and 6 months postoperatively ( Figs. 7 and 8 ). Now, the difference between them in millimetres was recorded. As it was not possible to standardize the amount of immediate height gain (it is a case dependent) so, the percentage of height gain for each group was calculated and compared with those of the other group.