International Journal of Periodontics & Restorative Dentistry, 06/1999

The purpose of this study was to determine if and how the biologic width is reestablished following surgical crown lengthening. Crown-lengthening surgery was performed on the right or left maxillary and mandibular central and lateral incisors of three adult monkeys, with contralateral teeth serving as unoperated controls. Twelve weeks after surgery, tissue blocks were removed for histologic analysis. The results of a histometric evaluation indicate that the biologic width is reestablished following surgical crown lengthening. The junctional epithelium generally migrates to the apical level of root planing. Space for the supracrestal connective tissue fiber groups is created by crestal resorption of alveolar bone.

The present study was conducted to define, when restoring extensive loss of dentin, the configuration of the restoration that will best reproduce the biomechanical properties of the intact original tooth in terms of resilience and stress distribution. The treatment of 1/3-crown fractures and 2/3-crown fractures was investigated using different designs of facial porcelain veneers with and without underlying composite buildup. The stress distribution and tooth compliance were assessed in a numeric model reproducing a 2-dimensional buccolingual cross section of an incisor. A 50-N facial force was applied to simulate an incisal impact situation. The facial surface tangential stresses were calculated, and the maximum displacement (horizontal direction) at the most incisal node of the enamel surface was also recorded and used to calculate the tooth compliance (ie, displacement/load or resilience) for each test condition. Tensile stresses were generated on the facial surface of the porcelain laminates with a similar pattern for all test conditions, the cervical part of the crown being the most quiescent area. Substantial differences appeared in the incisal half of the crown, the lowest stresses being observed for extensively fractured teeth restored without composite buildup (facial peaks at about 33 MPa). Fractured teeth restored with minimal veneers and a 'dentin-like' composite buildup showed stress patterns similar to the intact tooth (facial peaks at about 50 MPa). The natural tooth gave the highest tooth compliance or flexibility. All restorative designs featured increased tooth stiffness. However, the original tooth compliance was almost restored when composite was used to replace the missing dentin, with the porcelain acting only as a facial and incisal enamel substitute. When restoring crown-fractured incisors, tooth compliance and stress distribution can be modulated by the combination of composite and ceramics. Optimized configurations can be reached to reproduce the original biomechanical behavior of the intact tooth. The use of ceramic alone generates low stress concentrations, but also less compliant restored teeth.

The purpose of this investigation was to examine the short-term effect of apically repositioned flap surgery on clinical and microbiologic parameters in patients with adult periodontitis. A total of 11 patients with moderate to advanced periodontitis received apically repositioned flap surgery. Subjects were monitored during a 3-month pretreatment phase, the baseline surgical phase, and for 3 months postsurgery. Clinical assessments including plaque accumulation, gingival redness, suppuration, bleeding on probing, pocket depth, and attachment level were made at 6 sites per tooth. Subgingival plaque samples were taken from the mesial aspect of each tooth and the presence and levels of 29 subgingival taxa were determined using whole genomic DNA probes and checkerboard DNA-DNA hybridization. The mean levels and percentage of sites colonized by each species (prevalence) were computed for each subject at each visit. After surgery, there was a significant decrease in mean pocket depth and percentage of sites exhibiting gingival redness. Significant decreases were seen in the percentage of sites that had attachment levels 4 mm, with a significant increase in the percentage of sites with attachment levels of 4 to 6 mm after therapy. The mean total DNA probe count for all bacterial species was significantly decreased by both scaling and root planing and surgical therapy. P gingivalis and B forsythus, 2 bacteria previously shown to be susceptible to mechanical therapy, exhibited statistically significant decreases in mean total DNA probe count. Because surgical therapy decreased levels of the suspected periodontal pathogens C rectus, P nigrescens, and C gracilis, it may be speculated that there was a potential added beneficial effect of surgery on the periodontal microbiota.

The advent of cylindric titanium implants and the prevalence of periodontal disease have necessitated a restoration that facilitates the performance of oral physiotherapy. The use of the conical crown as a metallic covering over natural teeth and implants-with a suprastructure that is retained through a specific degree of convergence without cement or screws-allows access for enhanced oral hygiene practices, while providing for esthetic and functional goals.

A surgical protocol is described for the placement of Emdogain enamel matrix derivative during new attachment procedures. Three cases with infrabony defects were treated and a significant probing attachment level (PAL) gain, probing depth reduction, and bone fill were evident on clinical probing and during reentry procedures. The first patient presented a combined one-walled and circumferential defect at a maxillary central incisor. After 1 year the PAL gain was 7 mm. The second case showed a 3-walled defect distal to a maxillary canine. After 1 year the PAL gain was 8 mm, and a reentry procedure showed an almost total fill of the defect. The third patient presented a combined one- and 3-walled defect in the most apical part of the mesial aspect of a maxillary central incisor. One year after the surgical procedure, an orthodontic treatment was performed in this patient. After 6 more months the soft tissue showed a very good esthetic appearance, the papilla height was fully maintained, and there was a PAL gain of 5 mm; 18 months after surgery, reentry showed a significant regeneration of hard tissue that was impossible to probe. Because of these encouraging clinical results, further studies should be initiated to investigate the efficacy of the enamel matrix derivative in new attachment procedures.

A novel surgical procedure specifically designed to access interdental spaces in the regenerative treatment of deep intrabony defects is presented. This procedure (simplified papilla preservation flap, SPPF) was designed to provide surgical access to interproximal bony defects while preserving interdental soft tissues, even in narrow interdental spaces and posterior teeth. A modified mattress suture allows coronal positioning of the buccal flap and primary closure of the interdental space without tension. The modified mattress suture minimizes the collapse of the membrane into the defect. An experimental population of 18 patients in good general health who presented with one intrabony defect each was selected for this clinical study. The application of the SPPF in combination with bioresorbable membranes resulted in clinical attachment level (CAL) gains of 4.9 ± 1.8 mm at 1 year. The difference between baseline CAL and 1 year CAL was highly clinically and statistically significant. The residual pockets at 1 year measured 3.6 ± 1.2 mm. A slight increase in gingival recession was noted. Primary closure of the flap in the interdental space over the membrane was obtained in 100% of the cases after completion of surgery and maintained in 67% of the cases during the healing period. The application of SPPF in combination with bioresorbable barrier membranes allowed primary closure of the interdental space in most of the treated sites and resulted in consistent CAL gains at 1 year.

The biologic principle of guided bone regeneration has been successfully used to regenerate alveolar ridges. The objective of this pilot study was to clinically and histologically evaluate the demineralized freeze-dried bone membrane. Four premolar teeth were extracted from two dogs, and the remaining alveolar bone was surgically reduced in width and height to produce Class III ridge defects. After a 2-month healing period, mucoperiosteal flaps were elevated, and demineralized freeze-dried cortical columns were used as space maintainers. Bone membranes were used as barriers. The animals were sacrificed at 3 months and the surgical areas were recovered and processed for histologic evaluation. Results showed ridge augmentation in all sites. Clinically, the augmented areas appeared to have the same hardness as the surrounding bone on the periphery of the experimental site. After elevation of a mucoperiosteal flap, the bone membrane could be seen. Histologically, the bone membrane acted as an efficient barrier, excluding the nonosteogenic tissues. New bone formation underneath the membrane was found in all specimens. This study suggests that a bone membrane in combination with a space maintainer can guide new bone formation to regenerate localized chronic alveolar ridge defects.

Single-stage implants are frequently used, but their use in the anterior dentition has not been widely published. The purpose of this case report is to present the esthetic result of a single-stage implant to replace a maxillary central incisor, and to demonstrate the unconventional use of a 15-degree angled ITI implant. A 15-degree 12-mm hollow cylinder was placed with the angle reversed facially. The emergence profile of the adjacent roots was matched with the transmucosal portion, turning at the osseous crest. The implant was restored after 6 months with an ITI gold coping and transverse screw-retained crown. The gingival margin and the papillae were shaped by the transmucosal portion and the restoration. To date, the implant has been loaded for 24 months with an ideal soft tissue esthetic and radiographic appearance.