[Comparison of initial periodontal therapy and its correlation with white blood cell level in periodontitis patients with or without diabetes mellitus].

OBJECTIVE: To compare the clinical efficacy of initial periodontal therapy in periodontitis patients with or without type 2 diabetes mellitus and its correlation with white blood cell counts. METHODS: In this study, 32 chronic periodontitis patients without systemic disease (CP group) and 27 chronic periodontitis patients with type 2 diabetes mellitus (CP+DM group) were enrolled. At admission, all the patients went through periodontal examination and fasting blood examination(baseline). Probing depth (PD), attachment loss (AL), bleeding index (BI), plaque index (PLI), white blood cells (WBC) counts and fasting blood glucose (FBG) were recorded respectively, while hemoglobin A1c (HbA1c) was recorded only in CP+DM group. After that, initial periodontal therapy was performed. All the tests were repeated 3 and 6 months after treatment. The changes of periodontal clinical indexes and WBC levels were compared between the two groups before and after treatment, and the correlation between WBC and periodontal clinical indexes and glucose metabolism indexes were analyzed by generalized linear mixed model. RESULTS: At baseline, the periodontal inflammation and destruction were similar in CP and CP+DM group, but the WBC level was significantly higher in CP+DM groups [(6.01±1.26)×109/L vs. (7.14±1.99)×109/L, P=0.01]. After 3 and 6 months of initial periodontal therapy, the mean PD, AL, BI, and PLI in CP+DM and CP groups were significantly lower than the baseline, and the PD in CP+DM group was further decreased by 6 months compared with 3 months [(3.33±0.62) mm vs. (3.61±0.60) mm, P < 0.05]. However, none of these periodontal indexes showed significant difference between the two groups by 3 or 6 months. In CP+DM group, HbA1c at 3 months and 6 months were significantly lower than the baseline [(7.09±0.79)% vs. (7.64±1.16)%, P < 0.05; (7.06±0.78)% vs. (7.64±1.16)%, P < 0.05], and FBG was significantly lower than the baseline by 6 months [(7.35±1.14) mmol/L vs. (8.40±1.43) mmol/L, P < 0.05]. The WBC level in CP group was significantly lower than the baseline level by 3 months [(5.35±1.37)×109/L vs. (6.01±1.26)×109/L, P < 0.05], while that in CP+DM group was significantly lower than the baseline level by 6 months [(6.00±1.37)×109/L vs. (7.14±1.99)×109/L, P < 0.05]. The analysis of genera-lized linear mixed model showed that WBC level was significantly positively correlated with PD and FBG (P < 0.05). CONCLUSION: Initial periodontal therapy can effectively improve the periodontal clinical status of patients with or without type 2 diabetes mellitus, and have benefits on glycemic control in diabetic patients. However, the response of periodontal indexes and WBC level to initial therapy were relatively delayed in diabetic patients. WBC plays an important role in the correlation between diabetes mellitus and periodontitis.

[Study on periodontal status of patients with pre-diabetes].

Objective: To investigate periodontal status of patients with pre-diabetes and evaluate the prevalence of periodontal pathogens in oral cavity. Methods: All the subjects were under regular care in urban area of Beijing, including 88 subjects with normal blood glucose (normal blood glucose group), 27 pre-diabetic patients (pre-diabetic group), 58 well-controlled diabetic patients (glucose well controlled group) and 72 poor-controlled diabetic patients (glucose poor controlled group). Whole unstimulated saliva samples were collected before periodontal examination. Periodontal parameters, including plaque index (PLI), probing depth (PD), bleeding index (BI), bleeding on probing (BOP) and clinical attachment loss (CAL), were examined at mesial-buccal and distal-lingual sites of each tooth. Number of missing teeth was recorded. DNA was extracted from the salivary deposition, Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Campylobacter rectus (Cr), and Prevotella nigrescens (Pn) were detected by using PCR method based on 16SrRNA. Periodontal status and prevalence and quantity of the pathogens under various blood glucose states were compared. Results: The PD scores of four groups had no statistical differences. The CAL [(2.29±1.35) mm] and the number of missing teeth[2.0 (7.0)] in pre-diabetic group were significantly lower than that in glucose poor controlled group [(3.07±1.45) mm, P=0.04 and 5.0 (10.0), P=0.04, respectively]. The number of missing teeth in pre-diabetic group [2.0 (7.0)] was significantly lower than that in glucose well controlled group [5.0 (9.0), P=0.02]. The percent of bleeding on probing [BOP(+)%] in pre-diabetic group [(63.89±20.03)%] was significantly higher than that in normal blood glucose group [(54.51±22.29)%, P=0.04] and glucose well controlled group [(53.12±21.77)%, P=0.03]. The prevalence of Pg in pre-diabetic group (81.5%) was significantly higher than that in glucose poor controlled group (54.2%, P=0.02). The prevalence of Tf in pre-diabetic group (96.3%) was significantly higher than that in glucose poor controlled group (76.4%, P=0.01). Meanwhile the quantity of Pg [1.58 (4.75)] and Tf [5.46 (7.77)] in pre-diabetic group were significantly higher than that in glucose poor controlled group [0.60 (1.87), P=0.01 and 1.63 (3.06), P<0.01, respectively]. The quantity of Pn [0.85 (1.68)] in pre-diabetic group was significantly higher than that in normal blood glucose group [0 (1.02), P=0.04]. Conclusions: Pre-diabetic patients showed severe periodontal infection and BOP(+)% than other three groups and had high risk-level of periodontitis.

[Preliminary study of subgingival microorganism changes after glycine powder air-polishing treatment during periodontal maintenance phase].

Objective: To research the variation of subgingival microorganisms after 65 µm glycine powder air-polishing (GPAP) in patients with periodontitis during periodontal maintenance phase and make comparison with conventional method. Methods: From Department of Periodontology, Peking University School and Hospital of Stomatology, twenty-one patients at the age of 35-72 (8 males and 13 females) who were systematically healthy were recruited in this study. According to splitting-mouth design, one side of a mouth was randomly assigned to the experiment group (21 patients, 248 teeth, 1 488 sites) with 65 µm GPAP therapy while the opposite side served as the control group (21 patients, 249 teeth, 1 494 sites) with ultrasonic scaling plus polishing paste therapy. The clinical periodontal parameters including probing depth (PD), bleeding index (BI), bleeding on probing (BOP) and plaque index (PLI) were recorded. Using sterile currette, the subgingival plaque samples were collected at the mesio-buccal site of the first or second molars at baseline, 2, 4, 8 and 12 weeks after therapy, respectively. After Congo red staining, the microorganisms were classified into cocci, bacilli and spirochetes and counted respectively. Results: All clinical periodontal parameters have no difference between two groups at baseline and after treatment 12 weeks. In the experiment group and the control group, PD ([2.33±0.90] and [2.37±1.18] mm), BI (0.96±0.70 and 0.98±0.78) and PLI (0.00[1.00] and 0.00[1.00]) of two groups after treatment 12 weeks were better than those at baseline (PD: [2.48±1.17] and [2.46±0.99] mm; BI: 1.07±0.72 and 1.08±0.75; PLI: 0.00 [1.00] and 0.00 [1.00]) (P<0.05). But BOP(+)% was observably reduced only in the control group after treatment 12 weeks ([17.25±2.21]% vs [25.23±2.83]%) (P<0.05). The percentages of cocci, bacilli and spirochetes were stable and there were not significant differences between the two groups (P>0.05). Conclusions: After 65 µm GPAP therapy, the differences of proportion of subgingival microorganisms are not significant, while the control group has the same trend. The spirochetes remained at a low level, but they rebounded fasterly in the test group than that in the control group. The results indicate that 65 µm glycine powder air-polishing has the similar clinical effects compared with ultrasonic scaling plus polishing paste. However, the clinical indications should be limited to the patients with shallow pockets and without obvious dental calculus.

Suppressing the loss of ultracold molecules via the continuous quantum Zeno effect.

We investigate theoretically the suppression of two-body losses when the on-site loss rate is larger than all other energy scales in a lattice. This work quantitatively explains the recently observed suppression of chemical reactions between two rotational states of fermionic KRb molecules confined in one-dimensional tubes with a weak lattice along the tubes [Yan et al., Nature (London) 501, 521 (2013)]. New loss rate measurements performed for different lattice parameters but under controlled initial conditions allow us to show that the loss suppression is a consequence of the combined effects of lattice confinement and the continuous quantum Zeno effect. A key finding, relevant for generic strongly reactive systems, is that while a single-band theory can qualitatively describe the data, a quantitative analysis must include multiband effects. Accounting for these effects reduces the inferred molecule filling fraction by a factor of 5. A rate equation can describe much of the data, but to properly reproduce the loss dynamics with a fixed fillingfraction for all lattice parameters we develop a mean-field model and benchmark it with numerically exacttime-dependent density matrix renormalization group calculations.

Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium.

We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic 167Er fermions, spin polarized in the lowest Zeeman sublevel. In this system, elastic collisions arise purely from universal dipolar scattering. Based on cross-dimensional rethermalization experiments, we observe a strong anisotropy of the scattering, which manifests itself in a large angular dependence of the thermal relaxation dynamics. Our result is in good agreement with recent theoretical predictions. Furthermore, we measure the rethermalization rate as a function of temperature for different angles and find that the suppression of collisions by Pauli blocking is not influenced by the dipole orientation.

Measurements of Tan's contact in an atomic Bose-Einstein condensate.

A powerful set of universal relations, centered on a quantity called the contact, connects the strength of short-range two-body correlations to the thermodynamics of a many-body system with zero-range interactions. We report on measurements of the contact, using rf spectroscopy, for an (85)Rb atomic Bose-Einstein condensate (BEC). For bosons, the fact that contact spectroscopy can be used to probe the gas on short time scales is useful given the decreasing stability of BECs with increasing interactions. A complication is the added possibility, for bosons, of three-body interactions. In investigating this issue, we have located an Efimov resonance for (85)Rb atoms with loss measurements and thus determined the three-body interaction parameter. In our contact spectroscopy, in a region of observable beyond-mean-field effects, we find no measurable contribution from three-body physics.

Anisotropic polarizability of ultracold polar 40K87Rb molecules.

We report the measurement of the anisotropic ac polarizability of ultracold polar (40)K(87)Rb molecules in the ground and first rotationally excited states. Theoretical analysis of the polarizability agrees well with experimental findings. Although the polarizability can vary by more than 30%, a "magic" angle between the laser polarization and the quantization axis is found where the polarizability of the |N=0,m(N)=0> and the |N=1,m(N)=0> states match. At this angle, rotational decoherence due to the mismatch in trapping potentials is eliminated, and we observe a sharp increase in the coherence time. This paves the way for precise spectroscopic measurements and coherent manipulations of rotational states as a tool in the creation and probing of novel quantum many-body states of polar molecules.

Evolution of the normal state of a strongly interacting Fermi gas from a pseudogap phase to a molecular Bose gas.

Wave-vector resolved radio frequency spectroscopy data for an ultracold trapped Fermi gas are reported for several couplings at T(c), and extensively analyzed in terms of a pairing-fluctuation theory. We map the evolution of a strongly interacting Fermi gas from the pseudogap phase into a fully gapped molecular Bose gas as a function of the interaction strength, which is marked by a rapid disappearance of a remnant Fermi surface in the single-particle dispersion. We also show that our theory of a pseudogap phase is consistent with a recent experimental observation as well as with quantum Monte Carlo data of thermodynamic quantities of a unitary Fermi gas above T(c).

Verification of universal relations in a strongly interacting Fermi gas.

Many-body fermion systems are important in many branches of physics, including condensed matter, nuclear, and now cold atom physics. In many cases, the interactions between fermions can be approximated by a contact interaction. A recent theoretical advance in the study of these systems is the derivation of a number of exact universal relations that are predicted to be valid for all interaction strengths, temperatures, and spin compositions. These equations, referred to as the Tan relations, relate a microscopic quantity, namely, the amplitude of the high-momentum tail of the fermion momentum distribution, to the thermodynamics of the many-body system. In this work, we provide experimental verification of the Tan relations in a strongly interacting gas of fermionic atoms by measuring both the microscopic and macroscopic quantities in the same system.

Dipolar collisions of polar molecules in the quantum regime.

Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are strong, long-range and spatially anisotropic. This is in stark contrast to the much studied dilute gases of ultracold atoms, which have isotropic and extremely short-range (or 'contact') interactions. Furthermore, the large electric dipole moment of polar molecules can be tuned using an external electric field; this has a range of applications such as the control of ultracold chemical reactions, the design of a platform for quantum information processing and the realization of novel quantum many-body systems. Despite intense experimental efforts aimed at observing the influence of dipoles on ultracold molecules, only recently have sufficiently high densities been achieved. Here we report the experimental observation of dipolar collisions in an ultracold molecular gas prepared close to quantum degeneracy. For modest values of an applied electric field, we observe a pronounced increase in the loss rate of fermionic potassium-rubidium molecules due to ultracold chemical reactions. We find that the loss rate has a steep power-law dependence on the induced electric dipole moment, and we show that this dependence can be understood in a relatively simple model based on quantum threshold laws for the scattering of fermionic polar molecules. In addition, we directly observe the spatial anisotropy of the dipolar interaction through measurements of the thermodynamics of the dipolar gas. These results demonstrate how the long-range dipolar interaction can be used for electric-field control of chemical reaction rates in an ultracold gas of polar molecules. Furthermore, the large loss rates in an applied electric field suggest that creating a long-lived ensemble of ultracold polar molecules may require confinement in a two-dimensional trap geometry to suppress the influence of the attractive, 'head-to-tail', dipolar interactions.

Controlling the hyperfine state of rovibronic ground-state polar molecules.

We report the preparation of a rovibronic ground-state molecular quantum gas in a single hyperfine state and, in particular, the absolute lowest quantum state. This addresses the last internal degree of freedom remaining after the recent production of a near quantum degenerate gas of molecules in their rovibronic ground state, and provides a crucial step towards full control over molecular quantum gases. We demonstrate a scheme that is general for bialkali polar molecules and allows the preparation of molecules in a single hyperfine state or in an arbitrary coherent superposition of hyperfine states. The scheme relies on electric-dipole, two-photon microwave transitions through rotationally excited states and makes use of electric nuclear quadrupole interactions to transfer molecular population between different hyperfine states.

Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules.

How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single partial-wave scattering, and quantum threshold laws provide a clear understanding of the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near-quantum-degenerate gas of polar 40K87Rb molecules prepared in their absolute ground state, we report experimental evidence for exothermic atom-exchange chemical reactions. When these fermionic molecules were prepared in a single quantum state at a temperature of a few hundred nanokelvin, we observed p-wave-dominated quantum threshold collisions arising from tunneling through an angular momentum barrier followed by a short-range chemical reaction with a probability near unity. When these molecules were prepared in two different internal states or when molecules and atoms were brought together, the reaction rates were enhanced by a factor of 10 to 100 as a result of s-wave scattering, which does not have a centrifugal barrier. The measured rates agree with predicted universal loss rates related to the two-body van der Waals length.

A dipolar gas of ultracold molecules.

Ultracold polar molecular gases promise new directions and exciting applications in collisions and chemical reactions at ultralow energies, precision measurements, novel quantum phase transitions, and quantum information science. Here we briefly discuss key experimental requirements for observing strong dipole-dipole interactions in an ultracold dipolar gas of molecules. We then survey current experimental progress in the field with a focus on our recent work creating a near quantum degenerate gas of KRb polar molecules [Ni et al., Science, 2008, 322, 231].

Ultracold polar molecules near quantum degeneracy.

We report the creation and characterization of a near quantum-degenerate gas of polar 40K-87Rb molecules in their absolute rovibrational ground state. Starting from weakly bound heteronuclear KRb Feshbach molecules, we implement precise control of the molecular electronic, vibrational, and rotational degrees of freedom with phase-coherent laser fields. In particular, we coherently transfer these weakly bound molecules across a 125 THz frequency gap in a single step into the absolute rovibrational ground state of the electronic ground potential. Phase coherence between lasers involved in the transfer process is ensured by referencing the lasers to two single components of a phase-stabilized optical frequency comb. Using these methods, we prepare a dense gas of 4 x 10(4) polar molecules at a temperature below 400 nK. This fermionic molecular ensemble is close to quantum degeneracy and can be characterized by a degeneracy parameter of T/T(F) = 3. We have measured the molecular polarizability in an optical dipole trap where the trap lifetime gives clues to interesting decay mechanisms. Given the large measured dipole moment of the KRb molecules of 0.5 Debye, the study of quantum degenerate molecular gases interacting via strong dipolar interactions is now within experimental reach. PACS numbers: 37.10.Mn, 37.10.Pq.

Bragg spectroscopy of a strongly interacting 85Rb Bose-Einstein condensate.

We report on measurements of the excitation spectrum of a strongly interacting Bose-Einstein condensate. A magnetic-field Feshbach resonance is used to tune atom-atom interactions in the condensate and to reach a regime where quantum depletion and beyond mean-field corrections to the condensate chemical potential are significant. We use two-photon Bragg spectroscopy to probe the condensate excitation spectrum; our results demonstrate the onset of beyond mean-field effects in a gaseous Bose-Einstein condensate.

A high phase-space-density gas of polar molecules.

A quantum gas of ultracold polar molecules, with long-range and anisotropic interactions, not only would enable explorations of a large class of many-body physics phenomena but also could be used for quantum information processing. We report on the creation of an ultracold dense gas of potassium-rubidium (40K87Rb) polar molecules. Using a single step of STIRAP (stimulated Raman adiabatic passage) with two-frequency laser irradiation, we coherently transfer extremely weakly bound KRb molecules to the rovibrational ground state of either the triplet or the singlet electronic ground molecular potential. The polar molecular gas has a peak density of 10(12) per cubic centimeter and an expansion-determined translational temperature of 350 nanokelvin. The polar molecules have a permanent electric dipole moment, which we measure with Stark spectroscopy to be 0.052(2) Debye (1 Debye = 3.336 x 10(-30) coulomb-meters) for the triplet rovibrational ground state and 0.566(17) Debye for the singlet rovibrational ground state.

Using photoemission spectroscopy to probe a strongly interacting Fermi gas.

Ultracold atomic gases provide model systems in which to study many-body quantum physics. Recent experiments using Fermi gases have demonstrated a phase transition to a superfluid state with strong interparticle interactions. This system provides a realization of the 'BCS-BEC crossover' connecting the physics of Bardeen-Cooper-Schrieffer (BCS) superconductivity with that of Bose-Einstein condensates (BECs). Although many aspects of this system have been investigated, it has not yet been possible to measure the single-particle excitation spectrum (a fundamental property directly predicted by many-body theories). Here we use photoemission spectroscopy to directly probe the elementary excitations and energy dispersion in a strongly interacting Fermi gas of (40)K atoms. In the experiments, a radio-frequency photon ejects an atom from the strongly interacting system by means of a spin-flip transition to a weakly interacting state. We measure the occupied density of single-particle states at the cusp of the BCS-BEC crossover and on the BEC side of the crossover, and compare these results to that for a nearly ideal Fermi gas. We show that, near the critical temperature, the single-particle spectral function is dramatically altered in a way that is consistent with a large pairing gap. Our results probe the many-body physics in a way that could be compared to data for the high-transition-temperature superconductors. As in photoemission spectroscopy for electronic materials, our measurement technique for ultracold atomic gases directly probes low-energy excitations and thus can reveal excitation gaps and/or pseudogaps. Furthermore, this technique can provide an analogue of angle-resolved photoemission spectroscopy for probing anisotropic systems, such as atoms in optical lattice potentials.

Collisional stability of fermionic Feshbach molecules.

Using a Feshbach resonance, we create ultracold fermionic molecules starting from a Bose-Fermi atom gas mixture. The resulting mixture of atoms and weakly bound molecules provides a rich system for studying few-body collisions because of the variety of atomic collision partners for molecules; either bosonic, fermionic, or distinguishable atoms. Inelastic loss of the molecules near the Feshbach resonance is dramatically affected by the quantum statistics of the colliding particles and the scattering length. In particular, we observe a molecule lifetime as long as 100 ms near the Feshbach resonance.

p-Wave Feshbach molecules.

We have produced and detected molecules using a p-wave Feshbach resonance between 40K atoms. We have measured the binding energy and lifetime for these molecules and we find that the binding energy scales approximately linearly with the magnetic field near the resonance. The lifetime of bound p-wave molecules is measured to be 1.0+/-0.1 ms and 2.3+/-0.2 ms for the ml=+/-1 and ml=0 angular momentum projections, respectively. At magnetic fields above the resonance, we detect quasibound molecules whose lifetime is set by the tunneling rate through the centrifugal barrier.

Potential energy of a 40K Fermi gas in the BCS-BEC crossover.

We present a measurement of the potential energy of an ultracold trapped gas of 40K atoms in the BCS-BEC crossover and investigate the temperature dependence of this energy at a wide Feshbach resonance, where the gas is in the unitarity limit. In particular, we study the ratio of the potential energy in the region of the unitarity limit to that of a noninteracting gas, and in the T=0 limit we extract the universal many-body parameter beta. We find beta=-0.54_{-0.12};{+0.05}; this value is consistent with previous measurements using 6Li atoms and also with recent theory and Monte Carlo calculations. This result demonstrates the universality of ultracold Fermi gases in the strongly interacting regime.