International Journal of Periodontics & Restorative Dentistry, 04/2009

The objective of this investigation was to present a novel method to facilitate and accelerate geometry acquisition/modification during the fabrication of finite element models of tooth restorations. Microcomputed tomographic data, stereolithography, and surface-driven automatic meshing were used to generate premolar finite element models with different occlusoproximal cavity preparations and corresponding composite resin restorations. Occlusal loading was simulated by nonlinear contact analysis. Cuspal widening was measured and correlated with existing experimental data for model validation. Cuspal widening during application of a 150-N load ranged from 2.7 µm for the unrestored tooth to 5 to 179 µm for the different preparations and 3.5 to 6.9 µm for the different restorations. The described method was efficient and generated detailed and valid three-dimensional finite element models. These models were used to study the effect of restorative procedures on cuspal deflection and revealed high cuspal strains associated with mesioocclusodistal preparations and restorations compared to individual two-surface preparations. This study confirmed that, whenever possible during removal of interdental decay, an intact marginal ridge should be maintained to avoid threesurface preparations such as the mesio-occlusodistal and the high cuspal strain associated with this design.

This study investigated a minimally invasive surgical procedure for alveolar ridge augmentation that combined recombinant human platelet-derived growth factor BB (rhPDGF-BB) and three different matrices. The minimally invasive tunneling ridge augmentation procedure was applied to 12 patients randomized into three groups: rhPDGF-BB (0.3 mg/mL) was combined with freeze-dried bone allograft (FDBA; group A), anorganic bovine bone graft (ABBG; group B), or anorganic bovine bone graft/mineralized collagen bone substitute (ABBG/MCBS; group C). Computed tomography (CT) scans were obtained presurgically and prior to 14- week re-entry surgery. Clinical reentry revealed adequate bone volume to place implants in all patients in groups A and B and two of four patients in group C. Trephine core biopsies were obtained and evaluated by microCT, backscatter scanning electron microscopy (BE-SEM), and light microscopy. New bone formation was consistently observed with BE-SEM and histologic analysis for group A and B specimens. Newly formed woven and lamellar bone were in close contact with graft particles. The ABBG/MCBS specimens (group C) had more variable results, with fibrous encapsulation of graft particles and limited histologic evidence of new bone formation. Within the limits of this study, the FDBA and ABBG carriers appear to be appropriate scaffolds to deliver rhPDGF-BB for ridge augmentation via minimally invasive surgical techniques.

Two hundred forty interdental papilla sites in 20 healthy patients were investigated. Interdental papilla heights of maxillary anterior teeth were measured from the gingival zenith, along with clinical crown lengths. Percentages of papilla height to crown length were computed and defined as papilla proportion, mesial papilla proportion (MPP), and distal papilla proportion (DPP). Mean interdental papilla heights of maxillary anterior teeth were 4 mm mesially and 4.1 mm distally. Mean MPP was 42% (n = 120), and mean DPP was 43% (n = 120). No significant differences were found between MPP and DPP for maxillary incisors (P >= .5). Canines demonstrated a trend toward increased distal papilla heights. Papilla proportions were approximately 40% for all tooth groups. A more apical position of distal papilla heights from anterior to posterior teeth, mentioned in the literature, was not confirmed by the present data.

This study was designed to demonstrate the use of the relatively novel tunneling technique for root coverage with acellular dermal matrix (ADM) to treat Miller Class I and II gingival recession defects. Five subjects with two to five adjacent buccal gingival recession defects were treated with ADM using the tunneling technique for root coverage. A calibrated, blinded examiner measured clinical parameters, including probing depth, clinical attachment level, width of keratinized tissue, recession depth, recession width at 1 mm apical to the cementoenamel junction, gingival tissue thickness at 1 mm and 3 mm apical to the gingival margin, Plaque Index, Gingival Index, and Wound Healing Index, at different time intervals. Patient discomfort was recorded 14 days postoperatively, and an overall quality assessment was recorded 180 days postoperatively. Results showed an average of 61% defect coverage (equal to 93.5% root coverage), and a 0.15-mm gain in tissue thickness was achieved 1 year postoperatively. This suggested that root coverage with ADM using the tunneling technique can be a viable alternative to traditional techniques, especially for multiple recession defects in maxillary premolar and anterior teeth.

The aim of this paper is to report on three patients who received unconventional implant treatment because of the presence of impacted teeth. To avoid invasive surgical removal of the impacted teeth and delayed implant treatment, implants were placed through the impacted teeth. Of the seven implants placed into four impacted teeth, all healed uneventfully except a short (8.5-mm) implant that became mobile after 4 months. One and three implants now have been loaded for 3.5 and 2 years, respectively. The two other implants were removed after 6 months of uneventful healing. These cases, although limited in number, suggest that implant placement through an impacted tooth might not interfere with implant integration or harm occlusal function, at least in the short term. More study is warranted before this unconventional procedure might be considered as a possible clinical option when, at an impacted tooth site, clinicians seek to avoid invasive surgery.

Demineralized bone matrix and cancellous bone chips in a reverse-phase medium carrier (DynaBlast, Keystone Dental) were used to augment the maxillary sinuses in 8 patients requiring 10 sinus augmentations. Clinical reentry after 6 to 7 months (mean, 6.2 months) and computed tomographic scan evaluation at 5 months demonstrated new bone formation as well as sufficient radiopaque volume to place implants in all sites. Microcomputed tomographic evaluation and histomorphometric analysis of sinus core biopsies confirmed the formation of new bone and demonstrated three distinctive mineralization patterns that have been previously described. DynaBlast can be considered a viable alternative to the use of autogenous bone or other types of grafting materials.

The goal of this investigation was to evaluate histologically and histometrically the healing process in dehiscence-type defects treated by enamel matrix derivative (EMD). Five adult female beagle dogs were used. Buccal osseous dehiscences were surgically created on the maxillary canines and the second and fourth premolars. Thirty defect sites were randomly assigned to treatment and control groups (15 defect sites for each group). The treatment group received EMD application, while the control groups received no EMD. After 4 months of healing, the dogs were sacrificed and tissue blocks were prepared. Histometric parameters were employed to evaluate the type of periodontal tissues that formed in the defects. All created dehiscence defects in the test sites treated by EMD had formed functional connective tissue fibers inserted into regenerated cellular cementum. The mean amount of apicocoronal regenerated cementum was 3.74 ± 0.43 mm in EMDtreated sites, whereas the control sites had not formed cementum in the created dehiscence defects (P .000). Statistically significant differences were found between treatment and control sites. Within the limits of this study, it can be concluded that EMD alone effectively promoted new cementum and functionally oriented connective tissue formation.

The purpose of this study was to evaluate histologically the root surfaces of teeth submitted to orthodontic and surgical extrusion procedures in a dog model. Eighteen adult male dogs, divided into six groups of three dogs each, were used in the study. Each animal underwent two procedures: rapid orthodontic extrusion and surgical extrusion of the maxillary lateral incisors. The animals were sacrificed to produce samples at 7, 14, 45, 90, 120, and 180 days after surgery for assessment of cross sections of the coronal, medial, and apical thirds of the treated teeth. At early time points, some active surface and inflammatory resorption was observed exclusively in the surgical extrusion group; however, samples collected at later times demonstrated functional repair of the resorption gaps in both groups. Ankylosis was observed as a minor event and was apparently of a transient nature in samples of the surgical extrusion group. The results demonstrate the importance of maintaining the periodontal ligament and cementum surface; both are vital for the prevention of root resorption. It may be postulated that orthodontic extrusion is more conservative and physiologic than surgical extrusion; however, the results showed that function was restored in both groups.

Periodontal reconstructive surgery procedures seek to correct mucogingival defects, including gingival recession. This case report describes the use of a subepithelial connective tissue graft (SCTG) associated with root-end fillings using mineral trioxide aggregate (MTA) for the treatment of Miller Class II recession with root apex exposure. A partial-thickness double pedicle flap was made, followed by root preparation with curette and bur finishing. The exposed root apex was removed and the canal was filled with MTA. An SCTG taken from the palate was placed over the root surface and covered with the double pedicle flap. Twelve months after treatment, a reduction from 11 mm to 1 mm in gingival recession was achieved, covering 91% of the root. Repair in the periapical region was determined with radiographs. A 1.0-mm probing depth was measured, and no bleeding was observed on probing. There was an adequate keratinized tissue band, along with esthetic tissue contour and coloration. This case report serves as an example of how the grafting of subepithelial connective tissue can be successfully accomplished in tandem with MTA for the treatment of isolated Miller Class II gingival recession with root apex exposure.