Extraoral vertical ramus osteotomy combined with internal fixation for the treatment of mandibular deformities.

Extraoral vertical ramus osteotomy (EVRO) is used in orthognathic surgery for the treatment of mandibular deformities. Originally, EVRO required postoperative intermaxillary fixation (IMF). EVRO has been developed using rigid fixation, omitting postoperative IMF. We examined retrospectively the long-term stability and postoperative complications for patients with mandibular deformities who underwent EVRO with internal rigid fixation. Patients who were treated with EVRO for a mandibular deformity in the period 2008-2017 at the Clinic of Oral and Maxillofacial Surgery, Mölndal, Sweden were included (N = 26). Overjet and overbite were calculated digitally and cephalometric analyses were performed preoperatively, and at three days, six months, and 18 months postoperatively. There was a general setback of the mandible, decreased gonial angle and reduced degree of skeletal opening. Excellent dental and vertical skeletal stabilities were seen up to 18 months postoperatively, although relapse was seen sagitally up to six months postoperatively. Since the overjet did not show any significant change over time, the sagittal skeletal changes have been attributed to dental compensation. There was no permanent damage to the facial nerve and 5.8% neurosensory damage to the inferior alveolar nerve was observed.

Nonresorbable versus resorbable sutures in oral implant surgery: a prospective clinical study.

BACKGROUND: Regarding the Brånemark implant system, nonresorbable sutures have been advocated for reapproximation of the flaps. Fast-absorbable sutures are frequently used in oral surgery, which is convenient for both the patient and the surgeon. It would be advantageous if fast-absorbable sutures are suitable in implant surgery as well. PURPOSE: The purpose of this study was to compare irradiated polyglactin 910 (Vicryl Rapide, Ethicon GmbH, Norderstedt, Germany) suture with a nonresorbable polyfilament suture (Supramid, Schwarz, Resorba GmbH, Nürnberg, Germany) used in oral implant surgery. MATERIALS AND METHODS: The study comprised 101 edentulous patients (52 females, 49 males) who were provided with 350 Brånemark implants. They were randomized to receive either Vicryl Rapide suture (n = 61) or 3-0 Supramid suture (n = 40). The patients were evaluated after 10 days and at the time of abutment surgery. Any wound complications and implant losses were recorded. RESULTS: The implant failure rate at abutment surgery was low (1.2%), and no difference was seen between the two suture groups. A higher incidence of complications (mainly wound dehiscence) was found in the absorbable suture group, especially when a continuous suture was used. CONCLUSIONS: The results of this study indicate that it is possible to use irradiated polyglactin 910 sutures in oral implant surgery without affecting the rate of early implant failure. However, it is recommended to add interrupted "security sutures" if a continuous suture technique is used in combination with fast-absorption suture material.

Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts: a 3- to 5-year follow-up clinical report.

Forty three patients with severely resorbed maxillae who had been referred for implant treatment were assigned to 1 of 3 treatment options: bone grafting and implant placement (graft group), modified implant placement with no bone grafting (trial group), or optimized complete dentures (no-implant group). Sixteen, 20, and 7 patients, respectively, were assigned to the 3 groups. The patients have been examined annually, and at the time of this report they had been followed for 3 to 5 years after treatment. At the 1-year follow-up, 10% (22 of 221) of the implants had been lost, and at the 2-year follow-up, 18% of the implants had been lost (40 of 221; 25% in the graft and 13% in the trial group); after that time, no further losses occurred. Life table analysis showed cumulative success rates of 82% in the graft group and 96% in the trial group after 1 year, and 74% and 87%, respectively, at the final examination after 3 to 5 years. The failure rate was higher in smokers than in non-smokers. A substantial reduction of the grafted bone, especially of onlay grafts, occurred early after grafting surgery in many patients. Mean marginal peri-implant bone loss was 0.6 mm during the period from prosthesis connection to the 1-year follow-up, and from the 1-year to the 3-year follow-up, average peri-implant bone loss was 0.3 mm in the graft group and 0.5 mm in the trial group. The results corroborated previous findings that patients with severely resorbed maxillae have an increased risk of implant failure in comparison to patients with good bone quantity and quality. However, in this investigation, practically all implant losses occurred during the first 2 years, whereupon a steady state seemed to follow for up to 5 years after loading.

Histologic evaluation of the bone integration of TiO(2) blasted and turned titanium microimplants in humans.

Twenty-seven patients received 2 microimplants each during implant surgery. One microimplant was blasted with 25 microm sized particles of TiO(2); the other was left as machined i.e. a turned surface. Before insertion the surface topography was characterized with an optical confocal laser profilometer. The surface roughness was greater than standard implants, and was similar for both surface modifications averaging over all parts of the implant i.e. tops, valley and flanks. The mean surface roughness from flank measurements only replicated previously reported findings: i.e. significantly rougher surfaces on blasted implants. After a mean healing period of 6.3 months in the maxillae and 3.9 months in the mandible, the microimplants and surrounding tissue were removed with a trephine burr. The histomorphometrical evaluation demonstrated significantly higher bone-to-implant contact for the blasted implants, inserted in the maxilla or in the mandible. Significantly more bone was found inside the threaded area for the blasted implants in the mandible, but there was no difference for implants positioned in maxillae.

Influence of bicortical or monocortical anchorage on maxillary implant stability: a 15-year retrospective study of Brånemark System implants.

The present study evaluated implant survival and marginal bone loss in maxillae over a 15-year follow-up period as a function of either monocortical or bicortical implant anchorage. Of 207 standard Brånemark implants (10 mm in length) followed, 110 implants were judged to be monocortically anchored and 97 as bicortically anchored. The bicortically anchored implants failed nearly 4 times more often than the monocortical ones. Implant fractures accounted for over 80% of the observed failures and were found to affect the bicortical group almost 3 times more often. As tentative explanations, induction of increased stress and bending forces resulting from possible prosthetic misfit, presence of unfavorable arch relationships, or high occlusal tables in combination with bicortically anchored implants have been suggested, all indicating an overambitious fixation of the bicortical anchorage. Total marginal bone loss was low over the 15-year period and close to identical for the 2 groups, suggesting that the mode of cortical anchorage did not have any clinically significant influence on marginal bone remodeling.

Augmentation of exposed implant threads with autogenous bone chips: prospective clinical study.

BACKGROUND: Autogenous bone chips can be harvested during drilling of implant sites and may be used as a graft material for bone augmentation and coverage of exposed implant threads. PURPOSE: The aim of this prospective study was to evaluate the possibility of augmenting exposed implant threads with autogenous bone chips. MATERIALS AND METHODS: Twenty-one consecutive patients treated with screw-shaped oral implants with exposed threads due to buccal fenestration or marginal defects were augmented with autogenous bone harvested with a bone trap during drilling of the implant site. Both marginal (9 sites) and fenestration defects (12 sites), with 4 to 14 exposed implant threads, were registered clinically and with photography. The number of exposed implant threads was measured before and at second-stage surgery 6 months after augmentation. RESULTS: Complete bone coverage of the exposed implant threads was seen in 12 of the 21 implant sites. Six sites showed one to two remaining exposed threads, two showed about 40% coverage, and one showed flattening of the defect but with eight of nine exposed threads at 6 months follow-up. The mean bone gain was 81% in patients with a marginal defect and 82% in patients with a fenestration defect. CONCLUSION: The results from this clinical study show that it is possible to gain bone over exposed implant threads by augmentation with autogenous bone chips.

Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report.

Sixty-seven patients ranging in age from 16 to 86 years were included in this 3- to 5-year retrospective report focusing on implant survival and marginal bone remodeling in relation to implant diameter. A total of 299 Brånemark implants (3.75-mm diameter: 141; 4.0-mm diameter: 61; 5.0-mm diameter: 97) were placed in 16 completely and 51 partially edentulous arches. Seven of the 141 implants in the 3.75-mm-diameter group failed (5%). The corresponding value for the 4.0-mm-wide implants was 2 of 61 (3%). The highest failure rate, 18% (17/97), was seen for the 5.0-mm-diameter implants. The least favorable cumulative survival rates were seen in mandibles after 5 years and involving 4.0-mm- and 5.0-mm-diameter implants (84.8% and 73.0%, respectively). The marginal bone loss was generally low over the 5-year period. When the data were evaluated by the Cox regression analysis, a relationship was found between implant failure and implant diameter (P < .05), with a higher failure rate for the 5.0-mm-diameter implant. However, no relationship could be seen between implant failure and jaw type, or bone quality and quantity (P > .05). Neither was any relationship seen between marginal bone loss and bone quality and quantity, implant diameter, or jaw type when tested by multiple linear regression analysis (P > .05). A learning curve, poor bone quality, and changed implant design were suggested as possible reasons for the less positive outcome seen for the 5.0-mm-diameter implant. The fact that this implant was often used as a rescue implant when the standard ones were not considered suitable or did not reach initial stability was another plausible explanation.

Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts. A 1-year follow-up study.

Forty-three patients with severely resorbed maxillae who had been referred for implant treatment were assigned to one of three treatment groups: bone grafting and implant placement (graft group); modified implant placement but no bone grafting (trial group); or optimized complete dentures (no-implant group). Sixteen, 20, and 7 patients, respectively, were assigned to the three groups. At the 1-year follow-up, 10% of the implants had been lost. Only a few of the failures (3/22) occurred after prosthesis placement. The cumulative success rates were 83% in the graft group and 96% in the trial group. A substantial reduction of the grafted bone, especially of the onlay grafts, occurred in many patients. During the period from prosthesis connection to the 1-year follow-up, marginal peri-implant bone loss was on average 0.5 mm. Despite the often demanding procedures involved, all but one patient in each implant group said that they would undergo the treatment again. Most patients were very satisfied with the treatment outcome and their improved masticatory ability. Those who had renounced implant treatment appeared modestly adapted to their optimized dentures, but reported retention problems and less satisfaction with mastication.

Reintegration of mobilized titanium implants. An experimental study in rabbit tibia.

The possibility of re-establishing a rigid bone-implant fixation, i.e. osseointegration, after mechanical loosening of titanium implants, was evaluated in the rabbit tibia. Implants were inserted to engage either one (10 mm long, n = 24) or two (16 mm long, n = 24) cortical layers and were allowed to heal for six weeks. A re-entry was then made and 12 test implants in each group subjected to a reverse torque procedure until the integration failed. The remaining nonrotated 24 implants were left as controls. Thereafter all implants were allowed to heal for an additional period of six weeks. At the end of the 12 weeks, the degree of integration was assessed by measuring the removal torque for six test and six control implants in each group of implant lengths. Histomorphometric measurements were also performed on ground sections of the remaining test and control implants. A statistically significant higher removal torque was observed for the monocortical test implants than for the corresponding control implants. No differences were seen for the bicortical implants of either kind, however, no morphological differences could be revealed either, when comparing monocortical and bicortical test and control implants. These results indicate that osseointegrated implants that have been mobilized due to a traumatic disruption of the bone-implant interface, may reintegrate if allowed to heal for an additional period of time.

Mandibular bone graft in the anterior maxilla for single-tooth implants. Presentation of surgical method.

Nine patients with 10 implants were included in the study. A bone graft from the symphyseal region of the mandible was used to augment the ridge 4 months before implant insertion. All implant sites showed a sufficient amount of bone at the time of implant insertion. One implant was not integrated at the time of abutment connection. Bone resorption after augmentation was assessed by measurements of the width of the alveolar ridge at four different levels. The measurements were performed before and after the bone-grafting procedure, at implant insertion and at abutment connection. The bone resorption in the buccal/palatal direction was 60% when measured from the time of bone grafting to abutment connection. The bone resorption was already obvious after 4 months (25%). The results indicate that the described bone grafting technique is applicable in patients with a narrow alveolar ridge, even though the resorption of the graft was extensive.

Influence of implant diameters on the integration of screw implants. An experimental study in rabbits.

The influence of diameter on the integration of titanium screw-shaped implants was studied in the rabbit tibia by means of removal torque measurements and histomorphometry. Implants 3.0, 3.75, 5.0, and 6.0 mm in diameter and 6.0 mm long were inserted through one cortical layer in the tibial metaphyses of nine rabbits and allowed to heal for 12 weeks. The implants were then unscrewed with a torque gauge, and the peak torque required to shear off the implants was recorded. The histologic analysis in undemineralized ground sections comprised (1) a gross description of the implant sites and assessments of (2) the total implant length in bone and (3) in the cortical passage, as well as (4) the thickness of the cortical bone adjacent to the implants. From the removal torque values obtained and morphometric measurements, a mean shear stress value was calculated for each implant type. The biomechanical tests showed a statistically significant increase of removal torque with increasing implant diameter. The resistance to shear seemed to be determined by the implant surface in supportive cortical bone, whereas the newly formed bone at the periosteal and endosteal surfaces did not seem to have any supportive properties after 12 weeks. It is suggested that wide diameter implants may be used clinically to increase implant stability.

Influence of mono- and bicortical anchorage on the integration of titanium implants. A study in the rabbit tibia.

The study aimed to evaluate the removal torque and bone tissue response to titanium implants supported by one or two cortical layers. A total of 72 screw titanium implants, either 10 or 16 mm in length and 3.75 mm in diameter, were inserted in right and left tibiae of 18 adult New Zealand rabbits. The implants engaged either one or two cortical layers, and the animals were allowed a healing period of 6 or 12 weeks. The degree of integration was assessed by measuring the removal torque with a torque gauge manometer. Histomorphometric calculations were also performed in 10-microns-thick ground sections. All implants were clinically stable at the end of the experiment. The removal torque was two times higher for the bicortical implants after 6 weeks, and three times higher after 12 weeks, than for the monocortical ones. The 16-mm implants also showed a statistically higher amount of bone contact and bone area after 6 and 12 weeks, respectively, than the short ones. The results support bicortical anchorage of implants also in the clinical situation.

Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits.

In the present study, the influence of initial instability on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that they were either stable (control), rotation-mobile, or totally mobile. Implants were also inserted in the distal femoral condyles, representing an implantation bed with mainly cancellous bone, so they either showed no initial mobility (control) or were rotation-mobile. After 12 weeks of healing, the implants were retrieved, together with surrounding bone, fixed, dehydrated, and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone to titanium contact, and the amount of bone occupying the threads, were calculated, whereafter the outcome of the different locations were compared. All retrieved implants were clinically stable at the of the experiment. For the tibia sites, a statistically significant less bone to titanium contact, and a less amount of bone in the threads, were found for the totally mobile implants, as compared to the corresponding initially stable controls. Moreover, a statistically significant higher amount of bone was found in the threads of the rotation-mobile implants inserted in the femoral condyle as compared to their initially stable controls. The study indicated that initial rotation-mobility, independent if it occurs in cortical or trabecular bone, does not necessarily lead to an inferior integration of unloaded implants. However, initial total implant mobility within the cortical layer results in a statistically significant less amount of bone around the implants, as compared to stable controls.

Influence of soft tissue contamination on the integration of titanium implants. An experimental study in rabbits.

In the present study, the influence of peroperative soft tissue contamination on the healing of titanium implants was studied in 9 lop-eared rabbits. Titanium implants (Brånemark System) were inserted in the tibiae, a location with cortical bone only, in such a way that one group was inserted the standard way (control), and another group was contaminated for 30 s in the adjacent soft tissues, prior to insertion. The implants were allowed to heal for 12 weeks and were then retrieved together with surrounding bone, fixed, dehydrated and embedded in plastic resin. About 10 micron thick ground sections were prepared for light microscopic morphometry. The mineralized bone-to-titanium contact, and the amount of bone occupying the threads, were calculated for each implant, and the results of the two groups were compared. All retrieved implants were clinically stable at the end of the experiment. Regarding bone-to-titanium contact and bone area within the threads, a statistically nonsignificant difference was observed between the 2 groups. This study indicated that peroperative soft tissue contamination of c.p. titanium implants does not prevent osseointegration from occurring, when studied in the rabbit tibia.

Inferior alveolar nerve transposition in combination with Brånemark implant treatment.

The surgical protocol for inferior alveolar nerve transposition together with the Brånemark implant treatment is described. The short-term follow-up results of the first ten procedures are presented and show an initial 2- to 3-week duration of anesthesia. In all regions treated, signs of paresthesia/hypoesthesia have been registered for 1 to 7 months. After 6 months, seven of the regions recovered completely with regard to nerve sensation.