Biomedical subjects

G Zucchelli

Publications and source records attributed to G Zucchelli.

At least 19 recordsLinked to original sources

PubMed2006

Clinical and anatomical factors limiting treatment outcomes of gingival recession: a new method to predetermine the line of root coverage.

Complete root coverage is not always achievable, even in gingival recession with no loss of interproximal attachment and bone. The cemento-enamel junction is the most widely used referring parameter to evaluate root coverage results. The aim of the present study was to describe the most frequent diagnostic mistakes that may lead to incomplete root coverage in Miller Class I and II gingival recessions and to suggest a method to predetermine the level/line of root coverage in non-molar teeth. The line of root coverage (i.e., the level/line to which the soft tissue margin will be positioned after the healing process of a root coverage surgical technique) was predetermined by calculating the ideal vertical dimension of the interdental papilla of the tooth with the recession defect. This method was applied to 120 recession-type defects affecting non-molar teeth of 80 young healthy subjects that were treated with root coverage surgical procedures over the last 5 years. All recessions were Miller Class I or II and were associated with at least one of the following characteristics: 1) traumatic loss of the tip of the interdental papilla(e); 2) tooth rotation; 3) tooth extrusion with or without occlusal abrasion; and 4) a cervical abrasion defect with no evidence of the cemento-enamel junction. The line of root coverage may be considered the clinical cemento-enamel junction because it may substitute the anatomic cemento-enamel junction when this is no longer clinically visible on the tooth with recession or when the ideal conditions to obtain complete root coverage are not fully represented.

Dental Occlusion, Traumatic↗

PubMed2005

Coronally advanced flap with or without enamel matrix derivative for root coverage: a 2-year study.

AIM: The purpose of this study was to assess the ability of enamel matrix derivative (EMD) to improve root coverage with a coronally advanced flap (CAF) during a 2-year follow-up. METHODS: Fifteen patients each with two single and similar bilateral Miller Class I or II gingival recessions (30 recessions) were selected. Each recession was randomly assigned to the test group (CAF+EMD) or the control group (CAF only). Clinical parameters recorded at baseline and at 6, 12 and 24 months were recession depth (R), recession width (WR), probing depth (PD), clinical attachment level (CAL) and keratinized tissue (KT). RESULTS: Reduction of R resulted in a significant CAL gain in both groups, whereas PD was not altered. In the test group, R decreased from 4.07 mm (SD+/-0.59) at baseline to 0.47 mm (SD+/-0.74) at 24 months, corresponding to a mean root coverage (MRC) of 90.67%, whereas in the control group R shrank from 4.13 mm (SD+/-0.74) at baseline to 0.60 mm (SD+/-0.83) at 24 months (MRC=86.67%). Complete root coverage was achieved at 24 months in 73.33% and 60% of the two groups. A significant KT increase was observed in both groups. CONCLUSIONS: Root coverage outcomes were similar in both groups and no statistically significant differences were found at all between them. Hence, the additional use of EMD to CAF is not justified for clinical benefits of root coverage, but as an attempt of achieving periodontal regeneration rather than repair.

Adolescent↗

PubMed2005

Long-term outcome following treatment of multiple Miller class I and II recession defects in esthetic areas of the mouth.

BACKGROUND: Multiple recession defects can be successfully treated using envelope-type coronally advanced flaps. The aim of the present study was to evaluate the long-term (5 years) stability of clinical outcomes achieved with the surgery and the association between patient variables and long-term stability. METHODS: Seventy-three Miller Class I and II gingival recessions affecting 22 young, systemically healthy subjects were treated with coronally advanced flaps with no releasing incisions. All patients were instructed to perform a coronally directed roll technique to minimize the toothbrushing trauma to the gingival margin. The clinical reevaluation was made 1 year after the surgery. At this point, 13 patients took part in a supportive periodontal care program consisting of oral hygiene instructions, control of toothbrushing technique, and professional tooth cleaning every 4 months. The remaining nine patients did not participate and received only sporadic care by general dentists. At 5 years post-surgery, all patients were reexamined. RESULTS: At the 5-year examination, 94% of the root surfaces initially exposed due to gingival recession were still covered with soft tissue, and 85% of the treated recession defects showed complete coverage. Complete root coverage in all recessions was maintained in 15 out of 22 patients (68%). The long-term stability of the soft-tissue margin in the treated sites was significantly influenced by the patient's regular participation in the recall program and the susceptibility to gingival recession in other areas of the mouth. A statistically significant increase of keratinized tissue (0.80 +/- 0.64 mm) was observed between the 1- and 5-year observation visits, and the average increase of keratinized tissue between the baseline and the 5-year follow-up amounted to 1.38 +/- 0.90 mm. This increase was significantly affected by the baseline keratinized tissue (KT) and recession (REC) depth: in particular, the 5-year increase in the amount of keratinized tissue was greater in sites with a greater recession depth and lower amount of keratinized tissue at baseline. CONCLUSIONS: 1) The successful root coverage results obtained with the coronally advanced flap for multiple recession defects were well maintained over the 4-year observation period. 2) Negative patient characteristics such as a lack of compliance with a supportive care program and individual susceptibility to gingival recession were significantly associated with the recurrence in gingival recession. 3) The increase in keratinized tissue height that followed the coronally advanced flap procedure may be attributed to the tendency of the mucogingival line to regain its genetically determined position.

Adolescent↗

PubMed2004

Laterally moved, coronally advanced flap: a modified surgical approach for isolated recession-type defects.

BACKGROUND: Various modifications of the laterally sliding flap have been proposed to reduce the risk of gingival recession at the donor tooth site, but the reported root coverage predictability was quite low. The goal of the present study was to evaluate the effectiveness with respect to root coverage of a modified surgical approach of the laterally moved flap procedure for the treatment of an isolated type of recession defect. METHODS: One hundred and twenty (120) isolated gingival recessions (Miller Class I or II) with specific features of the keratinized tissue lateral to the defects were treated with a new approach to the laterally moved flap. The main surgical modifications consisted of the coronal advancement of the laterally moved flap and the different thickness during flap elevation. Clinical evaluation was made 1 year after the surgery. RESULTS: At the 1-year examination, 97% of the root surface was covered with soft tissue and 96 defects (80%) showed complete root coverage. A statistical and clinically significant increase of keratinized tissue was observed. These favorable results were accomplished with no change in the position of gingival margin or in the height of gingival tissue at the donor tooth/site. CONCLUSIONS: The laterally moved, coronally advanced surgical technique was very effective in treating isolated gingival recessions. It combined the esthetic and root coverage advantages of the coronally advanced flap with the increase in gingival thickness and keratinized tissue associated with the laterally moved flap. The ideal gingival conditions must be present lateral to an isolated recession defect in order to render the proposed surgical technique an highly effective and predictable root coverage surgical procedure.

Chlorhexidine↗

PubMed2003

Bilaminar techniques for the treatment of recession-type defects. A comparative clinical study.

OBJECTIVES: Complete root coverage is the primary objective to be accomplished when treating gingival recessions in patients with aesthetic demands. Furthermore, in order to satisfy patient demands fully, root coverage should be accomplished by soft tissue, the thickness and colour of which should not be distinguishable from those of adjacent soft tissue. The aim of the present split-mouth study was to compare the treatment outcome of two surgical approaches of the bilaminar procedure in terms of (i) root coverage and (ii) aesthetic appearance of the surgically treated sites. MATERIAL AND METHODS: Fifteen young systemically and periodontally healthy subjects with two recession-type defects of similar depth affecting contralateral teeth in the aesthetic zone of the maxilla were enrolled in the study. All recessions fall into Miller class I or II. Randomization for test and control treatment was performed by coin toss immediately prior to surgery. All defects were treated with a bilaminar surgical technique: differences between test and control sites resided in the size, thickness and positioning of the connective tissue graft. The clinical re-evaluation was made 1 year after surgery. RESULTS: The two bilaminar techniques resulted in a high percentage of root coverage (97.3% in the test and 94.7% in the control group) and complete root coverage (gingival margin at the cemento-enamel junction (CEJ)) (86.7% in the test and 80% in the control teeth), with no statistically significant difference between them. Conversely, better aesthetic outcome and post-operative course were indicated by the patients for test compared to control sites. CONCLUSIONS: The proposed modification of the bilaminar technique improved the aesthetic outcome. The reduced size and minimal thickness of connective tissue graft, together with its positioning apical to the CEJ, facilitated graft coverage by means of the coronally advanced flap.

Adolescent↗

PubMed2003

Enamel matrix proteins and bovine porous bone mineral in the treatment of intrabony defects: a comparative controlled clinical trial.

BACKGROUND: Various clinical studies have demonstrated that applying commercially available enamel matrix proteins (EMP) on the instrumented root surface during access flap surgery promotes clinically significant gains of clinical attachment and bone in intrabony defects. The aim of the present controlled clinical trial was to evaluate the adjunctive effect of filling the intrabony lesion with bovine porous bone mineral (BPBM) to a simplified papilla preservation (SPP) flap and EMP surgical procedure. METHODS: Sixty deep interproximal intrabony lesions in 60 patients with chronic periodontitis were treated with the SPP flap and EMP. In the 30 test defects, the intrabony component was filled with BPBM particles previously reconstituted with the EMP gel. A stringent infection control program was adopted for 1 year. The clinical and radiographical reevaluation was made 1 year after surgery. RESULTS: Both techniques resulted in clinically and statistically significant improvements between baseline and 1 year, in terms of clinical attachment level (CAL) gain, probing depth (PD) reduction, and radiographic bone fill; however, the BPBM test treatment showed statistically significantly greater CAL (5.8 +/- 1.1 versus 4.9 +/- 1.0) and radiographic bone (DEPTH) level gains (5.3 +/- 1.1 versus 4.3 +/- 1.5), and less increase in gingival recession (0.4 +/- 0.6 versus 0.9 +/- 0.5) than the control surgical procedure. CONCLUSION: The present study data supported the hypothesis that the adjunctive use of BPBM in grafting intrabony defects has the ability to improve clinical and radiographical outcomes achievable with EMP alone.

Adult↗

PubMed2002

Enamel matrix proteins and guided tissue regeneration with titanium-reinforced expanded polytetrafluoroethylene membranes in the treatment of infrabony defects: a comparative controlled clinical trial.

BACKGROUND: Several studies have documented the clinical efficacy of guided tissue regeneration (GTR) with non-resorbable expanded polytetrafluoroethylene (ePTFE) membranes and enamel matrix proteins (EMP) in the treatment of infrabony defects. The objective of this controlled clinical study was to compare the clinical outcomes of 3 surgical modalities in the treatment of deep interproximal infrabony defects. METHODS: Ninety (90) defects in 90 healthy subjects affected by chronic periodontitis were assigned to 1 of 3 treatment groups by blocking to prognostic variables. The test group was treated with the application of EMP and the simplified papilla preservation (SPP) technique; the second group was treated with titanium-reinforced ePFTE membranes and the SPP technique; and the third group was treated with the SPP technique used as access flap control procedure. No differences were observed in terms of baseline oral hygiene and defect characteristics among the 3 groups, indicating that the blocking approach was effective. A stringent infection control program was adopted for 1 year. RESULTS: The 1-year results indicated that: 1) all treatment modalities resulted in clinically significant improvements in clinical attachment levels (CAL) and reduction in probing depth (PD); 2) a statistically significant treatment effect was demonstrated comparing the EMP test, the membrane control, and the flap control groups in terms of CAL gains; 3) both the EMP test and the membrane control groups showed significant CAL gains compared to the flap control group; 4) a statistically significantly greater amount of CAL gain was demonstrated in GTR-treated compared to EMP-treated patients; 5) deeper residual probing depths but smaller increases in gingival recession were demonstrated following EMP therapy; and 6) smoking habits reduced the clinical outcomes of both regenerative procedures. CONCLUSIONS: The use of a regenerative procedure is indicated in the treatment of deep vertical bony defects since both the regenerative techniques (GTR and EMD) in the present study resulted in clinically and statistically significant improvements in clinical parameters compared to the access flap procedure. The use of EMP can be helpful in esthetically-sensitive sites and in reducing patient morbidity.

Adult↗

PubMed2001

The quenching of photosystem II fluorescence does not protect the D1 protein against light induced degradation in thylakoids.

In spinach thylakoids, the quenching of the singlet excited state in the photosystem II antenna by m-dinitrobenzene does not change the rate of the light induced degradation of the D1 reaction centre protein and offers only limited protection against photoinhibition itself. These results are discussed in terms of the role of non-photochemical quenching as a photoprotective strategy.

Dinitrobenzenes↗

PubMed2001

CD spectroscopy provides evidence for excitonic interactions involving red-shifted chlorophyll forms in photosystem I.

Selective destruction of the strongly dichroic red-shifted chlorophyll form (C709 nm) in photosystem I (PSI) trimers from Spirulina, by either non-selective high intensity illumination (photobleaching) or incubation with low concentrations of Triton X-100 is accompanied by changes in the circular dichroism spectrum of the same amplitude and of opposite sign at 677 nm. The data are interpreted in terms of a dimeric chlorophyll structure with excitonic bands at these two wavelengths. Similar photobleaching experiments with PSI-200 from maize also suggest the presence of bulk antenna/red form excitonic interactions.

Chlorophyll↗

PubMed2001

Involvement of uncoupled antenna chlorophylls in photoinhibition in thylakoids.

Evidence is presented, by means of both fluorescence and action spectroscopy, that a small, spectroscopically heterogeneous population of both Chl a and Chl b molecules is present in isolated spinach thylakoids and is active in photoinhibition. The broadness of the action spectrum suggests that degraded or incompletely assembled pigment-protein complexes may be involved.

Chlorophyll↗

PubMed2001

The simplified papilla preservation flap in the regenerative treatment of deep intrabony defects: clinical outcomes and postoperative morbidity.

BACKGROUND: The aims of the present multi-center, randomized, controlled clinical trial were: 1) to compare the efficacy of the simplified papilla preservation flap with and without a barrier membrane in deep intrabony defects; 2) to evaluate the postoperative morbidity and surgical complications; and 3) to preliminarily test the impact of baseline tooth mobility on clinical outcomes. METHODS: This parallel group, randomized, multi-center, controlled clinical trial involved 112 patients in 8 periodontal practices in 4 countries. A deep intrabony defect in each patient was accessed with the simplified papilla preservation flap. In the test defects, a bioabsorbable membrane was positioned. Patients' experiences with the surgical procedure and postoperative period were evaluated with a questionnaire. Clinical outcomes included clinical attachment level (CAL) and probing depth (PD) changes. RESULTS: Complete observations were available for 55 test and 54 control defects. CAL gains at 1 year were 3.5 +/- 2.1 mm in the guided tissue regeneration (GTR) group and 2.6 +/- 1.8 mm in the control group (P = 0.0117). CAL gains > or = 4 mm were observed in 50.9% of GTR sites and 33.3% of control sites. A significant center effect of 2.1 mm was observed (P= 0.01). Initial PD (P= 0.01) and baseline tooth mobility (P= 0.036) were significant covariates. During the procedure, 30.4% of test and 28.6% of controls reported feeling moderate pain, and subjects estimated the hardship of the procedure at 24 +/- 25 visual analog scale (VAS) units in the test group, and at 22 +/- 23 VAS in controls. In terms of the investigated outcomes, differences between test and control groups were not statistically significant. Among the postoperative complications, edema was most prevalent at week 1, and more frequently associated with the test treatment (P= 0.01). In the test group, 53.6% of membranes were exposed at week 3. CONCLUSIONS: The present study further supports the added benefits of guided tissue regeneration with respect to access flap alone in the treatment of deep intrabony defects, as well as the general efficacy of GTR in different clinical settings. Furthermore, our study indicates a possible influence of baseline tooth mobility on clinical outcomes.

Absorbable Implants↗

PubMed2000

A histological and electron-microscopic study of the architecture and ultrastructure of human periodontal tissues.

The structure of periodontal tissues is still far less understood than their clinical relevance would demand. Here the periodontal ligament and radicular cementum in healthy human teeth were studied by light microscopy, transmission and scanning electron microscopy. These observations showed that the extracellular matrix of periodontal ligament is composed of a loose plexus of wavy collagen fibrils immersed in a highly hydrated interfibrillar matrix. Only close to their cemental insertion do these fibrils gather in thick, parallel fascicles (Sharpey's fibres). As these cross the mineralization front, they become infiltrated by the mineral phase and continue directly with the cementum matrix. Sharpey's fibres, "extrinsic" and "intrinsic" fibres all appear to be the same fibres, which bend and branch repeatedly during their course within the thickness of the cementum. Because of its physical continuity with the cementum, a limited portion of the periodontal ligament approximately corresponding to the length of Sharpey's fibres remains unaffected by enzymatic digestion of the interfibrillar matrix while the rest of the ligament is completely dissolved. The findings here indicate that the periodontal ligament and dental cementum join by a continuity rather than a contiguity of structures; that the collagen-mineral relation in cementum has distinctive features in comparison to other hard tissues; that extrinsic and intrinsic fibres of cementum and the adjoining portion of periodontal ligament form a structural, mechanical and metabolic unit distinct from the central, more metabolically active portion of the periodontal ligament.

Collagen↗

PubMed2000

Thermal behavior of long wavelength absorption transitions in Spirulina platensis photosystem I trimers.

In photosystem I trimers of Spirulina platensis a major long wavelength transition is irreversibly bleached by illumination with high-intensity white light. The photobleaching hole, identified by both absorption and circular dichroism spectroscopies, is interpreted as the inhomogeneously broadened Q(y) transition of a chlorophyll form that absorbs maximally near 709 nm at room temperature. Analysis of the mean square deviation of the photobleaching hole between 80 and 300 K, in the linear electron-phonon frame, indicates that the optical reorganization energy is 52 cm(-1), four times greater than that for the bulk, short-wavelength-absorbing chlorophylls, and the inhomogenous site distribution bandwidth is close to 150 cm(-1). The room temperature bandwidth, close to 18.5 nm, is dominated by thermal (homogeneous) broadening. Photobleaching induces correlated circular dichroism changes, of opposite sign, at 709 and 670 nm, which suggests that the long wavelength transition may be a low energy excitonic band, in agreement with its high reorganization energy. Clear identification of the 709-nm spectral form was used in developing a Gaussian description of the long wavelength absorption tail by analyzing the changing band shape during photobleaching using a global decomposition procedure. Additional absorption states near 720, 733, and 743 nm were thus identified. The lowest energy state at 743 nm is present in substoichiometric levels at room temperature and its presence was confirmed by fluorescence spectroscopy. This state displays an unusual increase in intensity upon lowering the temperature, which is successfully described by assuming the presence of low-lying, thermally populated states.

Chlorophyll↗

PubMed2000

Selective quenching of the fluorescence of core chlorophyll-protein complexes by photochemistry indicates that Photosystem II is partly diffusion limited.

The spectral characteristics of fluorescence quenching by open reaction centres in isolated Photosystem II membranes were determined with very high resolution and analysed. Quenching due to photochemistry is maximal near 687 nm, minimal in the chlorophyll b emission interval and displays a distinctive structure around 670 nm. The amplitude of this 'quenching hole' is about 0.03 for normalised spectra. On the basis of the absorption spectra of isolated chlorophyll-protein complexes, it is shown that these quenching structures can be exactly described by assuming that photochemistry lowers the fluorescence yield of the reaction centre complex (D1/D2/cytb (559)) plus CP47, with quenching of the former complex being approximately double that of the latter complex. These data, which qualitatively indicate that there are kinetically limiting processes for primary photochemistry in the antenna, have been analysed by means of several different kinetic models. These models are derived from present structural knowledge of the arrangement of the chlorophyll-protein complexes in Photosystem II and incorporate the reversible charge separation characteristic of the exciton/radical pair equilibration model. In this way it is shown that Photosystem II cannot be considered to be purely trap limited and that exciton migration in the antenna imposes a diffusion limitation of about 30%, irrespective of the structural model assumed.

Journal Article↗

PubMed2000

The effect of chlorhexidine mouthrinses on early bacterial colonization of guided tissue regeneration membranes. An in vivo study.

BACKGROUND: Different membrane materials accumulate varying amounts of bacteria when exposed in the oral cavity, due to their textural and structural surface characteristics. The aim of the study was to evaluate the effect of chlorhexidine mouthrinses on the in vivo early bacterial colonization of 3 different guided tissue regeneration membrane materials. METHODS: Rectangular-shaped strips cut from 3 periodontal membranes (expanded polytetrafluoroethylene, polyglactin 910, and polylactic acid) were glued to removable devices adapted to the 2 upper quadrants in 8 dental students. In each student 1 quadrant was randomly selected as test side while the other served as control side. The experiment was divided in 2 phases: in the first phase plaque accumulation was followed for 4 hours while the second accumulation was followed for 24 hours. During the 4-hour experiment, students rinsed the test device twice (immediately following device application and after 2 hours) with 0. 12% chlorhexidine solution. The control device was rinsed with saline. In the second phase, students rinsed the test device with chlorhexidine and the control devices with saline 3 times (after device application and at 8 and 16 hours). Both the 4-hour and the 24-hour specimens were processed for scanning electron microscopy analysis. Fifty-four fields (at 200x magnification) were randomly selected and analyzed on each strip. Magnification was increased to determine the presence and morphotype of bacteria. The presence or absence of bacteria was assessed in a binomial fashion: the field was bacteria-positive when bacteria constituted the deposits covering the membrane surface. The microscopic field was negative (bacteria-negative) when no bacteria were observed. Bacteria-positive fields showing rods and filaments as prevalent morphotypes were recorded as rod-positive fields. RESULTS: The results of data analysis suggest that bacterial contamination of membrane materials is significantly reduced by treatment with chlorhexidine. They also suggest that other variables affect plaque accumulation as well; i.e., the time allowed (4 versus 24 hours) and the different membrane materials. The interaction between these 2 variables is also highly significant, thereby indicating a different rate of plaque accumulation on different materials, irrespective of the treatment with chlorhexidine. CONCLUSIONS: It was concluded that chlorhexidine mouthrinses may be effective in reducing and delaying the early bacterial accumulation on membrane materials although they are not able to fully prevent it. Membrane surface characteristics seem to be a more critical factor than the use of chlorhexidine, in influencing bacterial adhesion and colonization of barrier materials.

Adult↗

PubMed2000

Interleukin-1 gene polymorphisms and long-term stability following guided tissue regeneration therapy.

BACKGROUND: Specific interleukin (IL)-1 gene polymorphisms are associated with an increased susceptibility to severe periodontitis, increased inflammation, and increased likelihood of tooth loss during the maintenance phase after conventional periodontal therapy. The aim of the present study was to evaluate the impact of genotype on the maintenance of gained clinical attachment obtained after guided tissue regeneration (GTR) surgical therapy in deep intrabony defects. METHODS: Forty deep (> or =4 mm) interproximal angular bony defects with presurgical clinical attachment loss of >8 mm were treated by GTR using a non-absorbable expanded polytetrafluoroethylene (ePTFE) membrane. Membranes were surgically removed 4 to 6 weeks after surgery. Afterwards patients were placed on monthly recall for the first year and every 3 months for the following 3 years. At the 4-year re-evaluation, a IL-1 genetic susceptibility test was performed on all patients. RESULTS: Fourteen (35% of the 40 patients) were genotype-positive (+). At baseline no statistically significant differences were found between patients with different genotypes in full mouth plaque score (FMPS), full mouth bleeding score (FMBS), clinical attachment level (CAL), probing depth (PD), or gingival recession. At year 1 follow up visit, no statistically significant differences were noted between genotype + and genotype - patients in FMPS, FMBS, amount of CAL gain, decrease in PD, or increase in gingival recession. Sixteen patients had membrane exposure after the GTR procedures. In these patients, the amount of CAL gain (P <0.001) and PD reduction (P <0.01) 1 year after surgery was significantly lower than those observed in patients without membrane exposure. At the year 4 follow-up visit, no significant differences were found between genotype negative and positive patients in FMPS or FMBS and both groups showed a significant loss in CAL (P<0.001) and increase in PD (P<0.001) when compared to year 1 visit. No change in gingival recession was noted. Genotype + patients showed significantly more CAL loss (P<0.002) and increase in PD (P<0.001) between the years 1 and 4 when compared to genotype - patients. A significant association between genotype and stability of the regenerated attachment was also demonstrated. CONCLUSIONS: The results of this study demonstrate that genotype expression did not effect GTR treatment response at 1 year, but had a great impact on long-term stability (year 4). In a 3-year period, patients with positive IL-1 genotype lost about 50% of the first year gained CAL and were about 10 times more likely of experiencing > or = 2 mm CAL loss when compared to oral hygiene matched genotype-negative patients.

Adult↗

PubMed2000

Treatment of multiple recession-type defects in patients with esthetic demands.

BACKGROUND: When multiple recession defects affecting adjacent teeth in esthetic areas of the mouth are present, patient-related considerations suggest the selection of surgical techniques that allow all gingival defects to be simultaneously corrected with the soft tissue close to the defects themselves. The aim of the present study was to evaluate, with respect to root coverage, the effectiveness of a new surgical approach to the coronally advanced flap procedure for the treatment of multiple recession defects in patients with esthetic demands. METHODS: Twenty-two young systemically and periodontally healthy subjects with at least 2 recession-type defects affecting adjacent teeth in esthetic areas of the mouth were enrolled in the study. All recessions were Miller Class I or II. In each patient, all present recessions were treated at the same time with a modification of the coronally advanced flap technique. The clinical re-evaluation was made 1 year after the surgery. RESULTS: A total of 73 recessions (mean recession depth 2.8 mm) were treated; mean number of gingival recessions in each subject was 3.4. At the 1-year examination, on average, 97% of the root surface was covered with soft tissue and 64 defects (88%) showed complete root coverage. Complete root coverage in all recessions was achieved in 16 out of 22 patients (73%), and no statistically significant relationship was found between the root coverage results and the number of recession defects treated in each patient. A statistically significant increase of keratinized tissue (0.6 mm) was observed after 1 year; this increase was inversely correlated (P <0.001) with the amount of presurgical keratinized tissue. The multiple regression model showed that the final result, in terms of root coverage, was significantly affected by the initial recession depth and by the amount of presurgical keratinized tissue. Greater reductions in recession depth were observed in the cases with worse initial conditions and with lesser amount of keratinized tissue apical to the recession defect. CONCLUSIONS: The results of the present study demonstrated that the proposed surgical technique was very effective for the treatment of multiple gingival recessions affecting teeth in esthetic areas of the mouth and that these successful root coverage results could be achieved irrespective to both the number of recessions simultaneously treated during the surgical intervention and the presence, before surgery, of a minimal amount of keratinized tissue apical to the defects.

Adolescent↗

PubMed1999

Thermal sensitivity of the red absorption tail of the photosystem II reaction center complex.

The red tail of the absorption spectrum of the D1-D2-cytb559 complex, defined as the absorption signal not described by the two Gaussian sub-bands associated with the intense electronic transitions at 680 and 683 nm, exhibits anomalous temperature behavior. This tail was analyzed in the temperature interval between 80 and 300 K in terms of the mean square deviation (sigma2) of the total Qy absorption band and by Gaussian sub-band decomposition. The value of the average optical reorganization energy (Snum) obtained from the temperature dependence of sigma2 for the whole absorption band was 32 cm(-1), and changed to 16-20 cm(-1) after subtraction of the sub-bands describing the red tail. This latter value is in agreement with the hole burning literature data for chlorophyll bound to proteins, and indicates that the rather high value for the apparent optical reorganization energy obtained by analysis of the total Qy band of the D1-D2-cytb559 complex is determined by the temperature sensitivity of the red tail. This suggests that the long wavelength absorption tail might be due to vibrational transitions associated with vibrational modes in the range of 80-150 cm(-1) which are thermally accessible and give rise to an absorption signal on the low-energy side of the (0,0) transition. On the basis of this assumption, the electron-phonon coupling strength (S) for these modes is estimated to be in the range 0.028-0.18. This interpretation furthermore supports the idea that the electronic transition near 683 nm is that of a monomer chlorophyll.

Absorption↗