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The purpose of the study was to investigate root lengthening during orthodontic treatment in relation to the age of the patient, the developmental stage of the root, and the anticipated growth. Specifically, the potential benefit of treating young teeth was addressed. The sample consisted of 80 patients with Angle Class II division 1 malocclusions, treated with extraction of at least two maxillary first premolars, and edgewise technique with 0.018-inch slot brackets. Additionally, a cross-sectional control group of 66 untreated individuals matched to gender, and pre- and post-treatment age of the experimental group was included. Crown and root lengths of the maxillary incisors were measured on peri-apical radiographs before and after treatment, and corrected for image distortion. The stage of root development before treatment was recorded. Root elongation during treatment was found for 50 out of the 280 examined teeth. Age at treatment start was significantly higher among the patients showing root shortening of the lateral incisors during treatment than among those showing root elongation (P < 0.05). The stage of root development was significantly related to the direction of root length change, i.e. shortening or elongation. Roots elongated during treatment did not differ in length from untreated teeth of similarly aged individuals. There was no significant difference in the extent of root lengthening between the roots elongated during treatment and the normal root lengthening in age-matched untreated individuals. Post-treatment root length was significantly related to pre-treatment age. Roots that were incompletely developed before treatment reached a significantly greater length than those that were fully developed at the start of treatment. The results of this study show a definite advantage for younger teeth with regard to post-treatment root length. This finding may influence treatment planning strategy.

This study evaluated site-by-site the relations between subgingival microbial colonization and gingival tissue reactions. Experimental, deep periodontal defects were established at buccal surfaces of mandibular and maxillary canine teeth in 5 beagle dogs. The root surfaces were instrumented by a flame-shaped, fine-grained, rotating diamond point, or by a sharp curet. Following a 10-day postsurgical healing period, the dogs were fed a plaque-inducing diet for 70 days. The animals were then sacrificed and tissue blocks of the experimental sites including teeth and periodontal tissues were secured. The buccal gingiva was removed and processed for histomorphometric analysis while the teeth were prepared for scanning electron microscopic evaluation of the extent of subgingival microbial colonization. The results revealed that inflammatory cell density in the junctional epithelium and in the connective tissue were positively correlated to subgingival microbial colonization (P < 0.01). Furthermore, the degree of significance decreased with increasing distance from the plaque. The present study demonstrates that a close relation may exist between the extent of subgingival microbial colonization and inflammatory gingival tissue reactions.

Effects of topical citric acid application on tissue maturation was studied in standardized periodontal defects in 6 beagle dogs. Following elevation of facial mucoperiosteal flaps, fenestration defects, 3 mm in diameter, were made through the cortical bone and recessed 0.5 mm into the dentin of maxillary canines. 1 defect in each dog was conditioned with a saturated solution of citric acid for 3 min and then rinsed with saline. Control defects in contralateral teeth were treated with saline only for the same length of time. The defects were covered with an expanded polytetrafluoroethylene membrane and the flaps repositioned and sutured. 14 days postsurgery, healing appeared more advanced along the defect walls and floor than in the center of the defect in all instances. Histometrically, citric acid-conditioned defects exhibited a higher density of collagen fibers along the defect walls and floor and adjacent to the barrier membrane as well as more advanced resolution of the residual blood clot than the surgical controls. Differences in fibroblast density within specimen pairs were non-significant. All control defects but none of the acid-conditioned defects showed an artifactual split between the dentin walls and the granulation tissue. This study failed to support the contention that topical application of citric acid to root surfaces may delay healing following periodontal surgery.

Periodontal health reflects a balance between harmful and protective elements in the gingival margin area. The total plaque mass, specific periodontopathogens, and local environmental factors may challenge this balance. The aim of this retrospective study was to evaluate the effect of proximal root grooves as a risk factor in periodontal attachment loss. One-hundred and three (103) extracted, formalin-stored, single-rooted teeth showing loss of attachment and having one non-grooved and one grooved proximal root surface were selected for the study. Following staining in 0.1% toluidine blue to visualize attached periodontal ligament remnants, the teeth were examined in a light microscope under incident light. On each tooth, loss of attachment was measured along the long axis of the root from the cemento-enamel junction to the most coronal level of the stained periodontal ligament remnants on mesial as well as on distal surfaces. Incisors and premolars were grouped separately. For both groups, a statistically significant greater loss of attachment was present on grooved than on non-grooved surfaces (P < 0.0001). Generally, there was a direct relationship between groove location and maximum loss of attachment. The results indicate that proximal root grooves should be considered in periodontal diagnosis, prognosis, and treatment planning.

The effect of citric acid conditioning of the root surface in conjunction with gingival flap surgery including barrier membranes (expanded polytetrafluoroethylene) was clinically evaluated in 26 intrabony periodontal defects in 23 patients. Control treatment included gingival flap surgery with barrier membranes alone. Twelve defects were treated with the experimental and 14 with the control protocol. Healing was evaluated 12 months after surgery. Initial probing depths approximated 6.9 mm and defect depths measured during surgery exceeded 4 mm. The patients exhibited good oral hygiene over the study interval as substantiated by low plaque and bleeding scores. Acid conditioning of the root surface did not enhance periodontal healing in this study, similar amounts of defect resolution were observed following either treatment protocol. Probing depth reduction generally approximated 1.8 mm; gain of clinical attachment, 0.8 mm; and defect bone fill, 1.2 mm. Under the prevailing conditions, the barrier membrane procedure apparently gave a healing result beyond which further improvement could not be achieved by root surface conditioning.

Previous studies have indicated that TiF4 and SnF2 differ in their demineralizing effect when applied topically to root surfaces at the same acidity. The aim of this study was to examine in more detail the outermost layer of root surface specimens by transmission electron microscopy (TEM) after short-term exposure to these acidic fluoride solutions. Root surface specimens were exposed for 1 min and 4 min to equimolar (1.1 M F) solutions of a) TiF4, native pH 1.0; b) SnF2, acidified to pH 1.0; and c) SnF2, native pH 2.5. The specimens were then rinsed in saline and processed for TEM. Exposure to TiF4 resulted in a partly demineralized zone 8-10 microns deep after 1 min and 5-27 microns deep after 4 min of application. A 0.1-micron-thick, electron-dense coating was present in all TiF4-treated specimens. Acidified SnF2 resulted in a completely demineralized zone, 4-7 microns deep, when applied for 1 min and 4 min, whereas SnF2 at native pH produced a 0.5- to 1.0-micron-wide partially demineralized zone. Unevenly distributed crystalline deposits were a frequent finding on SnF2-treated surfaces. The results indicate that solutions of TiF4 and SnF2 at native pH will cause only slight demineralization when applied topically to root surfaces.

Aqueous solutions of TiF4 cause a rapid uptake and a long-lasting retention of fluoride when applied to dentin. The aim of this study was therefore to investigate the pattern of fluoride release after TiF4 application in vitro, compared with SnF2 and NaF application. TiF4, SnF2, and NaF were applied for 4 min and 1 min to standardized areas of six groups of root surface specimens immersed in distilled water. Untreated specimens were used as controls. The water was changed daily for 30 days, and F concentrations measured by an ion-selective electrode. All test groups showed a rapid decline in F concentration. In the 4-min group F concentration more than double the detection limit of the F electrode could be registered the first 28 days for TiF4, 11 days for SnF2, and 7 days for NaF. In the 1-min group periods of F registration were shorter. Analysis of Sn by atomic absorption spectrophotometry showed decreasing concentrations in the first 12-day samples in the 1-min and 4-min groups. Traces of Ti were found in the first few samples, but no pattern of release could be observed.

Mandibular incisors were extracted and allowed to dry in air for 45 min. They were then root-planed extensively, leaving a cervical collar and the apical region uninstrumented, to prevent direct contact between root surface and alveolar bone after replantation while, at the same time, enabling precise and stable reseating of the tooth. Control teeth were replanted either without further treatment or after treatment with citric acid for 3 min. Experimental teeth were treated before replantation with 1% SnF2 for 5 min, 1% tetracycline HCl for 5 min, or 1% SnF2 followed by 1% tetracycline. Histometric analysis of healing in the root-planed areas showed minimal amounts of inflammatory resorption and ankylosis after 21 days in experimental teeth as compared with the control teeth. A persisting inflammatory reaction in the periodontal ligament without root resorption was, however, frequently seen. The observations confirm that the frequency of adverse healing reactions after delayed replantation of teeth from which nonvital soft tissue remnants have been removed can be reduced by demineralizing the root surface and preventing mechanical trauma to the root surface in the postoperative period. Root surface treatment with SnF2 followed by tetracycline resulted in complete absence of inflammatory resorption and ankylosis in this short-term experiment.

Root surfaces, exposed by periodontal disease, were studied after treatment with sodium hypochlorite. Observations of the anorganic specimens demonstrated that substantial changes occur in root surfaces incident to periodontal disease. A mineralized surface coating was seen in all areas of the involved root surface, although local regions occurred where the coating was apparently unmineralized. These findings generally confirmed the results of a previous study where the same specimens were studied without hypochlorite treatment. It is concluded that the coating is probably identical to the dental cuticle, and stems from adsorption of components of the gingival inflammatory exudate to the root surface. The coating may also be the carrier matrix for exogenous cytotoxic substances, previously thought to be located in the cementum. The findings may have implications for the way of treating periodontitis-involved root surfaces.

Acid-treatment of root surfaces as adjunct to periodontal reconstructive surgery may have deleterious effects on that part which remains in a supragingival location after healing. The present experiment aimed to examine whether recalcification of such root surfaces may occur. Cylindrical blocks of root dentin were prepared for 10 premolars, treated with citric acid and mounted in acrylic specimen holders which were worn in the mouth continuously for 14 d by two test subjects. The specimens were then sectioned and microradiographs produced. The citric acid had produced a completely demineralized surface zone in the root dentin and the subjacent hard tissue showed a zone of partially reduced mineral content. Following exposure to the oral cavity, the demineralized surface layer appeared unchanged in width. The subjacent zone, however, had been reduced in width in all instances when compared with control specimens from the same teeth.

Topical application of aqueous solutions of TiF4 to root surfaces has been shown to result in a rapid uptake of fluoride. The purpose of this study was to assess whether the application period and/or the ionic strength of the TiF4 solution can be reduced without a corresponding reduction in the fluoride uptake. Root halves from human teeth were exposed to (a) 1% TiF4 for 10 sec and 1, 2, and 4 min, and (b) 3.4% TiF4 for the same application periods. Root surface areas protected by nail polish served as controls. Transverse ground sections through the treated root surface areas were then prepared and analyzed for F by electron microprobe analysis. Most treated specimens showed F concentrations in the 0.60-1.94% range, whereas control surfaces contained less than 0.30%. Similar F concentrations were found in the surfaces treated with the two solutions. Reducing the application period resulted in a shallower penetration of F into the hard tissue but only a slight reduction of the F concentration in the surface layer. High concentrations of Ti were found on the surface of all treated specimens. This shows that both the application period and the ionic strength of TiF4 solutions can be considerably reduced and still enable a high uptake of fluoride. The results indicate that TiF4 may be an efficacious agent for F application to root surfaces under clinical conditions.

Early stages of connective tissue reattachment to surgically denuded cementum and root dentin following citric acid application were studied in fenestration wounds. Block specimens were obtained after seven, 14, and 21 days. Continuity between newly deposited collagen fibrils in the granulation tissue and unmasked dental matrix collagen had been established within seven days by interdigitation of fibrils in an up to 0.5 micron-wide zone at the cementum or dentin surface. Splicing of collagen at the fibrillar level by direct attachment to the severed end of matrix fibrils or by juxtapositioning of new and old fibrils was seen in rare instances only. At 14 and 21 days, distinct bundles of collagen fibrils inserted deeply into the orifice of dentinal tubules. Arrested and reversed surface resorption was encountered at all time points. At these sites as well, new collagen fibrils interdigitated with denuded matrix collagen, while some resorbed surfaces were characterized by absence of collagen continuity. The results lend continued support to the concept of reattachment based on interdigitation of collagen fibrils. However, since attachment is established even in the absence of this feature, a significant role for specific attachment substances not shown can also be postulated.

Root surfaces of extracted human teeth with advanced periodontal disease were studied by the apically migrated junctional epithelium, the topography characteristic of uninvolved cementum was frequently masked by a surface coating. The thickness of the coating increased in a coronal direction where it often blended with calculus. The observations indicate that this surface coating may originate from the inflammatory exudate and corresponds to the dental cuticle. The findings also indicate that the coating may be mineralized and may contain exogenous substances. These observations illustrate a need for further study and reexamination of the rationale for removal of tooth substance during scaling and root planing.